bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Predictions of Solar Open-Cycle Absorption Air Conditioning Systems in Three Climatic Regions
Authors: Ameel T. A. , Wood B. D. , Siebe Donald A. , Collier R. Kirk
Published: June 2008

Open-cycle absorption air conditioning is a promising type of solar-driven cooling system. It addresses, in a significant way, the problems of high solar collector costs and power requirements that are inherent in other solar cooling systems. Previous open-cycle absorption modeling studies have been very limited and included only the solar collection part of the system. The purpose of this study was to evaluate the potential for use of this type of system in various climatic regions of the United States. The study examines this promising type of air conditioning as a total system interacting dynamically with its environment. Mathematical analysis and computer simulation were used. System simulations were performed for three system design concepts. The Typical Meteorological Year data base for Miami, FL, Washington, D.C., and Phoenix, AZ, were used to estimate system potential. The best performance predictions resulted in approximately 60 percent of the seasonal load being met by an open-cycle absorption system in Miami, 70 percent in Washington, and 99 percent in Phoenix.
Two-Dimensional Model of a Space Station Freedom Thermal Energy Storage Canister
Authors: Kerslake T. W. , Ibrahim M. B.
Published: June 2008

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase-change salt contained in toroidal canisters for thermal energy storage. This paper presents results from heat transfer analyses of the phase-change salt containment canister. A two-dimensional, axisymmetric finite difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor-filled void regions, and forced convection in the heat engine working fluid. Void shape and location were prescribed based on engineering judgment. The salt phase-change process was modeled using the enthalpy method. Discussion of results focuses on the role of free convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between ground-based canister performance (in 1-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.
Characteristics of a Solar Pond Brine Reconcentration
System
Authors: Newell T. A. , Smith M. K. , Cowie R. G. , Upper J. M. , Cler C. L.
Published: June 2008

An active brine reconcentration system has been incorporated into the design of the University of Illinois half-acre salt gradient solar pond facility. An important feature of the system is its ability to keep precipitation from diluting the brine. Experimental data presented is in good agreement with a numerical simulation model of the evaporation process. The “film”-type evaporation process used in the system efficiently collects solar energy for evaporating water from brine. Parasitic electrical energy requirements for the evaporation system are 1.2 watts per square meter of evaporation surface area.
Experimental Study on the Recirculation of Homogeneous and Stratified Fluid Layers in the Advanced Solar Pond
Authors: Keren Y. , Rubin H. , Bemporad G. A.
Published: June 2008

The practical possibilities of constructing and operating a stable flow of homogeneous and stratified fluid layers in a solar pond were investigated in this study. A laboratory setup was prepared to carry out the experimental investigations. Transient and steady-state conditions were analyzed. A numerical model was developed to simulate heat, salt, and momentum transfer in the water body. The model was calibrated with the experimental data. Density and temperature measurements along the laboratory setup showed the configuration to be stable in all of the conditions which were analyzed. These experimental results indicated that through a proper multiselective injection and withdrawal procedure it was possible to create and control the double-diffusion stratified fluid layers, which characterizes the advanced solar pond.
A Coefficient to Characterize Mixing in Solar Water Storage Tanks
Authors: Davidson J. H. , Adams D. A. , Miller J. A.
Published: June 2008

A dimensionless coefficient is developed to characterize the level of mixing in solar water storage tanks. The MIX number, based on the height weighted energy, or moment of energy, in the tank, ranges from 0 to 1, with 0 representing a perfectly stratified (unmixed) tank and 1 representing a fully mixed tank. Limiting values are based on theoretical determinations of the maximum and minimum values of the moment of energy in a tank without mixing and a tank with complete mixing, respectively. Use of the new MIX number is illustrated by experimental data obtained in a 372-liter storage tank operated with both a conventional drop-tube inlet and a rigid, porous stratification manifold. The initial tank temperature profile, the temperature of the water entering the tank, and test duration are varied in three testing schemes. Fluid mixing is quantified by measured vertical temperature profiles and the dimensionless MIX number.
Experiments on Root Stresses of Helical Gears With Lead Crown and Misalignments
Authors: Hotait M. , Kahraman A.
Published: June 2008

In this study, the results of an experimental parametric study of the combined influence of shaft misalignments and gear lead modifications on the load distribution and tooth bending stresses of helical gear pairs are presented. A set of helical gear pairs having various amounts of total lead crown was operated under loaded, low-speed conditions with varying amounts of tightly controlled shaft misalignments. Gear teeth were instrumented through strips of strain gages along the face width of gears at the tooth fillet region at a roll angle that is near the start of the active profile. Variations of root strains along the face width were quantified for different levels of shaft misalignments and gear lead crown. The results presented demonstrate the direct link between the lead crown and gear misalignments as well as the effectiveness of the lead crown in preventing edge loading conditions due to misalignment. The results presented here form a database that should be available for a validation of gear contact models in terms of their ability to simulate misalignments.
Synthesis and Biological Evaluation of Some A,D-Ring Modified 16,17-Secoandrostane Derivatives
Authors: Djurendić Evgenija A. , Zaviš Marina P. , Sakač Marija N. , Kojić Vesna V. , Bogdanović Gordana M. , Penov Gaši Katarina M.
Published: June 2008

Starting from 3β-hydroxy-17-oxo-16,17-secoandrost-5-ene-16-nitrile (1), the new 16,17-secoandrostane derivatives 2-11 were synthesized. Protection of the 17-oxo function of compound 1 with ethylene glycol yielded compounds 2 and 3. The Oppenauer oxidation of 2 or oxidation with H2O2 in alkaline conditions gave the respective compounds 4 and 10. Epoxidation of compound 4 yielded a mixture of 4α,5α- and 4β,5β-epoxides 5 and 6 and a mixture of 4α,5α- and 4β,5β-epoxy-carboxamides 7 and 8. Opening of the oxirane ring of a mixture of compounds 5 and 6 with formic acid afforded the 4-hydroxy derivative 9. Anti-aromatase activity and in vitro cytotoxicity for three tumor cell lines (human breast adenocarcinoma ER+, MCF-7 as well as human breast adenocarcinoma ER-, MDA-MB-231, and prostate cancer, PC3) of selected compounds were evaluated. Compounds 2, 4, 9, and 10 showed a strong cytotoxicity for PC3 cells.
TREE DIAGRAMS FOR STRING LINKS II: DETERMINING CHORD DIAGRAMS
Authors: MELLOR BLAKE
Published: June 2008

In previous work [7], we defined the intersection graph of a chord diagram associated with a string link (as in the theory of finite type invariants). In this paper, we look at the case when this graph is a tree, and we show that in many cases these trees determine the chord diagram (modulo the usual 1-term and 4-term relations).
A NORMAL FORM FOR BRAIDS
Authors: BRESSAUD XAVIER
Published: June 2008

We present a seemingly new normal form for braids, where every braid is expressed using a word in a regular language on some simple alphabet of elementary braids. This normal form stems from analysing the geometric action of braid groups on curves in a punctured disk.
ACOUSTIC RADIATION FORCE AND TORQUE ON A SOLID ELLIPTIC CYLINDER
Authors: HASHEMINEJAD SEYYED M. , SANAEI R.
Published: June 2008

Exact expressions for the acoustic radiation torque and force components experienced by elastic cylinders of elliptic cross-section immersed in ideal fluids and placed in a progressive or standing wave field is developed. The classical method of eigen-function expansion and the pertinent boundary conditions are employed to develop analytical expressions in the form of infinite series involving Mathieu and modified Mathieu functions. The complications arising due to the nonorthogonality of angular Mathieu functions corresponding with distinct wave numbers as well as problems associated with the appearance of additional angular dependent terms in the boundary conditions are all avoided in an elegant manner by expansion of the angular Mathieu functions in terms of transcendental functions and subsequent integration, leading to a linear set of independent equations in terms of the unknown scattering coefficients. Numerical calculations of the radiation force and torque function amplitudes are performed in a wide range of frequencies and cross-sectional eccentricities for a stainless steel cylinder submerged in water. Particular attention is paid to assessment of the effects of cross-sectional ellipticity as well as incident field asymmetry on the acoustic radiation force/torque acting on the elliptical cylinder. Limiting case involving an elastic circular or elliptic cylinder in an ideal fluid is considered and fair agreements with well-known solutions are established.
A STOCHASTIC 2D-MODEL FOR CALCULATING VIBRATIONS IN RANDOM LAYERS
Authors: BALAZS PETER , KREUZER WOLFGANG , WAUBKE HOLGER
Published: June 2008

Vibrations induced by machinery and traffic have become of increasing concern in the last years, for example, when constructing buildings near railway lines. In this paper we will present a model designed to predict the vibration level in the ground. Since in practice it is nearly impossible to determine exact material parameters for soil layers, we use a model with a stochastic shear modulus G. Under moderate assumptions G can be split with the Karhunen–Loeve expansion into a mean value G0 and a stochastic part G stoch . Using a combination method of finite elements, Fourier transformation and Polynomial Chaos, it is possible to transform the partial differential equation describing the system into a matrix-vector formulation Kx = b which can be split into a deterministic and a stochastic part (K0 + Ks) x = b analog to the shear modulus. To keep the dimensions of the matrices involved with this system small, we use a Neumann-like iteration to solve it. Finally, results for a small example are presented.
ACCURATE TREATMENT OF A GENERAL SLOPING INTERFACE IN A FINITE-ELEMENT 3D NARROW-ANGLE PE MODEL
Authors: STURM FRÉDÉRIC , KAMPANIS NIKOLAOS A.
Published: June 2008

Parabolic equation models in 3D usually apply the "staircase" approximation to general range–varying interfaces between adjacent layers. This is the simplest technique available: it consists in neglecting range and azimuthal derivatives in the associated interface conditions. Our aim in this paper is to analyze the influence of the stair-step approximation technique, common to most 3D PE models, on a one-way sound wave propagation problem. We present a new finite-element 3D narrow-angle PE model which accurately treats the variable interface conditions. This is accomplished by using (i) an appropriate parabolized condition of the same aperture as the parabolic equation used, and (ii) a new change-of-variable technique which does not require any homotheticity condition of the layers as in previous works. Numerical simulations for the 3D wedge problem are presented. The convergence of the numerical solutions with respect to the azimuth is investigated. Unlike other 3D PE models working in cylindrical coordinates, the convergence tests have been carried out using a range-dependent number of points in azimuth. Numerical solutions obtained with the newly developed model are compared with a reference solution based on the image source and with a solution obtained with a 3D PE model that uses a stair-step technique.
A PROCESS FOR THE UPDATE AND REVIEW OF OPERATION AND TECHNOLOGY ROADMAPS
Authors: HOLMES CHRISTOPHER , FERRILL MICHAEL
Published: June 2008

In order to aid Singaporean small and medium sized companies identify and select emerging technologies for business benefit, the Operation and Technology Roadmapping (OTR) process has been introduced and applied to over seventy companies. To help these companies continue the adoption of roadmapping, an update process has been developed and applied to ten organizations. This paper introduces the operation and technology roadmap methodology for roadmap creation, and then explores the process used for updating roadmaps. The update process involves an initial review of the roadmap technologies, products and service and drivers to see how 'accurate' the past roadmaps forecasts were and to establish 'rules' for the update of the roadmap. Once the review has been carried out, a decision is then made as to whether create a new roadmap or to update the existing roadmap. If a new roadmap is to be created the existing OTR process is followed. If the roadmap is to be updated then more emphasis is placed on carrying forward the information already present on the roadmap, with the addition of some new ideas within the current roadmap framework.
Transient prenatal androgen exposure produces metabolic syndrome in adult female rats
Authors: Demissie Marek , Lazic Milos , Foecking Eileen M. , Aird Fraser , Dunaif Andrea , Levine Jon E.
Published: June 2008

Androgen exposure during intrauterine life in nonhuman primates and in sheep results in a phenocopy of the reproductive and metabolic features of polycystic ovary syndrome (PCOS). Such exposure also results in reproductive features of PCOS in rodents. We investigated whether transient prenatal androgen treatment produced metabolic abnormalities in adult female rats and the mechanisms of these changes. Pregnant dams received free testosterone or vehicle injections during late gestation, and their female offspring were fed regular or high-fat diet (HFD). At 60 days of age, prenatally androgenized (PA) rats exhibited significantly increased body weight; parametrial and subcutaneous fat; serum insulin, cholesterol and triglyceride levels; and hepatic triglyceride content (all P < 0.0125). There were no significant differences in insulin sensitivity by intraperitoneal insulin tolerance test or insulin signaling in liver or skeletal muscle. HFD had similar effects to PA on body weight and composition as well as on circulating triglyceride levels. HFD further increased hepatic triglyceride content to a similar extent in both PA and control rats. In PA rats, HFD did not further increase circulating insulin, triglyceride, or cholesterol levels. In control rats, HFD increased insulin levels, but to a lesser extent than PA alone (∼2.5- vs. ∼12-fold, respectively). We conclude that transient prenatal androgen exposure produces features of the metabolic syndrome in adult female rats. Dyslipidemia and hepatic steatosis appear to be mediated by PA-induced increases in adiposity, whereas hyperinsulinemia appears to be a direct result of PA.
Vasoinhibins: novel inhibitors of ocular angiogenesis
Authors: Clapp Carmen , Thebault Stéphanie , Arnold Edith , García Celina , Rivera José Carlos , de la Escalera Gonzalo Martínez
Published: June 2008

Disruption of the quiescent state of blood vessels in the retina leads to aberrant vasopermeability and angiogenesis, the major causes of vision loss in diabetic retinopathy. Prolactin is expressed throughout the retina, where it is proteolytically cleaved to vasoinhibins, a family of peptides (including the 16-kDa fragment of prolactin) with potent antiangiogenic, vasoconstrictive, and antivasopermeability actions. Ocular vasoinhibins act directly on endothelial cells to block blood vessel growth and dilation and to promote apoptosis-mediated vascular regression. Also, vasoinhibins prevent retinal angiogenesis and vasopermeability associated with diabetic retinopathy, and inactivation of endothelial nitric oxide synthase via protein phosphatase 2A is among the various mechanisms mediating their actions. Here, we discuss the potential role of vasoinhibins both in the maintenance of normal retinal vasculature and in the cause and prevention of diabetic retinopathy and other vasoproliferative retinopathies.
Relationships between exercise-induced reductions in thigh intermuscular adipose tissue, changes in lipoprotein particle size, and visceral adiposity
Authors: Durheim Michael T. , Slentz Cris A. , Bateman Lori A. , Mabe Stephanie K. , Kraus William E.
Published: June 2008

Small LDL and HDL particle size are characteristic of a proatherogenic lipoprotein profile. Aerobic exercise increases these particle sizes. Although visceral adipose tissue (VAT) has been strongly linked with dyslipidemia, the importance of intermuscular adipose tissue (IMAT) to dyslipidemia and exercise responses is less well understood. We measured exercise-associated changes in thigh IMAT and VAT and examined their relationships with changes in LDL and HDL particle size. Sedentary, dyslipidemic, overweight subjects ( n = 73) completed 8–9 mo of aerobic training. Linear regression models were used to compare the power of IMAT change and VAT change to predict lipoprotein size changes. In men alone ( n = 40), IMAT change correlated inversely with both HDL size change ( r = −0.42, P = 0.007) and LDL size change ( r = −0.52, P < 0.001). That is, reduction of IMAT was associated with a shift toward larger, less atherogenic lipoprotein particles. No significant correlations were observed in women. After adding VAT change to the model, IMAT change was the only significant predictor of either HDL size change ( P = 0.034 for IMAT vs. 0.162 for VAT) or LDL size change ( P = 0.004 for IMAT vs. 0.189 for VAT) in men. In conclusion, in overweight dyslipidemic men, exercise-associated change in thigh IMAT was inversely correlated with both HDL and LDL size change and was more predictive of these lipoprotein changes than was change in VAT. Reducing IMAT through aerobic exercise may be functionally related to some improvements in atherogenic dyslipidemia in men.
Expression of Class II Major Histocompatibility ComplexAntigens on Adult T Cells in Xenopus is Metamorphosis‐ Dependent
Authors: Rollins-Smith Louise A. , Blair Patrick
Published: June 2008

Class II major histocompatibility complex (MHC) antigens are expressed predominantly on B
lymphocytes and macrophages of tadpoles of the South African clawed frog, Xenopus laevis,
as is the pattern in lymphocyte populations of most mammals. However, unlike most
mammals, young postmetamorphic frogs show expression of class II MHC antigens on a
high proportion of thymocytes and most peripheral T and B lymphocytes. Using the J‐strain
of Xenopus and the anticlass II monoclonal antibody, 14A2, we have studied, by indirect
immunofluorescence, whether inhibition of metamorphosis would alter the pattern of
expression of class II antigens during ontogeny. In control animals, class II antigens were
virtually absent from thymic lymphocytes and peripheral T cells of normal untreated larvae,
but could be found in increasing numbers in both populations after metamorphosis (10‐12
weeks of age). In contrast, larvae, whose metamorphosis was inhibited by treatment with
sodium perchlorate, had relatively few class II+ thymic lymphocytes throughout the 6‐month
period of study, and the proportion of class II+ splenic lymphocytes was approximately
equal to that of IgM+ B lymphocytes. Thus, perchlorate‐treated animals retained the larval
pattern of class II epression, suggesting that emergence of class II+ T cells is dependent on
metamorphosis.
Conversion of Normal Ly‐1‐Positive B‐Lineage Cells into Ly‐1‐Positive Macrophages in Long‐Term Bone Marrow Cultures
Authors: Katoh Shigeki , Tominaga Akira , Migita Masahiro , Kudo Akira , Takatsu Kiyoshi
Published: June 2008

We obtained eight different cell lines in the long‐term bone marrow culture system that
showed a germ‐line configuration of the joining (J) region segments of the Ig heavy‐chain
(IgH) genes. Their surface markers were CD45R+, Ly‐1+, Lyb‐2+, cIgM‐, sIgM‐, Ia‐, Thy‐1‐,
Mac‐1‐, and IL‐2R (Tac)+. Use of very young mice and the presence of IL‐5 were important for preferential promotion of the survival of B‐lineage lymphocytes bearing the Ly‐1
markers. When we treated two of them (J8 and J10) with 5‐azacytidine for 24 h followed by
co‐culture with stromal cells and IL‐.5, they became Ly‐1+, sIgM+ B cells, and Ly‐1+, Mac‐1+
macrophagelike cells, respectively. After other early lymphoid lines (J1, J8, and J13) were
maintained by co‐culture with ST2 and IL‐5 for more than a year, they showed a heterogeneous
DNA rearrangement profile of the J region segment of the IgH gene, although only
J13 rearranged the κ‐light chain gene. Northern blot analysis revealed that these cell lines
expressed Cμ‐mRNA, and λ5‐mRNA, consistent with normal pre‐B cells. Intriguingly, J1, J8,
and J13 expressed c‐fms mRNA constitutively. When J13 cells were co‐cultured with ST2 and
GM‐CSF in place of ST2 and IL‐5, they acquired Mac‐1 expression and retained Ly‐1
expression. They were morphologically macrophages, nonspecific‐esterase‐positive, and
showed phagocytosis of latex beads. These results support evidence for a close relationship
between the myeloid and Ly‐1+ B‐cell pathways of differentiation, and indicate that our IL‐
5‐dependent clones are multipotential intermediates in differentiation from pro‐B cells to B
cells and macrophages.
The Ontogeny of Chicken Bursal Stromal Cells Defined by Monoclonal Antibodies
Authors: Wilson Trevor J. , Boyd Richard L.
Published: June 2008

Molecules expressed on lymphoid stromal cells influence the differentiation of lymphocytes.
We have examined the expression of stromal markers, identified by monoclonal antibodies,
in the chicken bursa of Fabricius during ontogenic development. These results are also
consistent with the hypothesis that medullary secretory cells are of mesenchymal origin,
whereas the basement membrane‐associated and some medullary epithelium are derived
from the endoderm. Our results have demonstrated the complexity of bursal stromal
development with determinants expressed on the adult medullary stellate cells (e.g., MUI‐57
and 62) and cortical macrophages (e.g., MUI‐66 and 72) detected on the early em.bryonic
tunica propria (e.g., MUI‐57, 66 and 72) or surface epithelium (e.g., MUI‐62 and 66). In
addition, we provide preliminary evidence regarding potential functions of these molecules
in stem cell colonization (MUI‐52), early B‐cell differentiation (e.g., MUI‐72), late bursal
B‐cell development (MUI‐69 and 71) and the follicle‐associated epithelium transport
mechanism (MUI‐61 and 73).
Immunoglobulin λ Gene Rearrangement Can Precede κ Gene Rearrangement
Authors: Berg Jörg , Mcdowell Mindy , Jäck Hans-Martin , Wabl Matthias
Published: June 2008

Immunoglobulin genes are generated during differentiation of B lymphocytes by joining
gene segments. A mouse pre‐B cell contains a functional immunoglobulin heavy‐chain gene,
but no light‐chain gene. Although there is only one heavy‐chain locus, there are two lightchain
loci: κ and λ.It has been reported that κ loci in the germ‐line configuration are never
(in man) or very rarely (in the mouse) present in cells with functionally rearranged λ‐chain
genes. Two explanations have been proposed to explain this: (a) the ordered rearrangement
theory, which postulates that light‐chain gene rearrangement in the pre‐B cell is first
attempted at the κ locus, and that only upon failure to produce a functional κ chain is there
an attempt to rearrange the λ locus; and (b) the stochastic theory, which postulates that
rearrangement at the λ locus proceeds at a rate that is intrinsically much slower than that at
the κ locus. We show here that λ‐chain genes are generated whether or not the κ locus has
lost its germ‐line arrangement, a result that is compatible only with the stochastic theory.
Differential Effects of IL‐2 and IL‐6 on the Development of Three Distinct Precursor T‐Cell Populations in the Thymus
Authors: Nakano Naoko , Kikutani Hitoshi , Kishimoto Tadamitsu
Published: June 2008

Three distinct T‐cell precursors: bone marrow cells that express low levels of the Thy‐1
antigen but no lineage markers (Thy‐1‐lo/BM); CD4‐, CD8‐, and CD3‐ thymocytes that
express low levels of the Thy‐1 antigen (Thy‐1‐lo/Thym); and CD4‐, CD8‐, and CD3‐ thymocytes that express high levels of the Thy‐1 antigen and the IL‐2 R α chain (Thy‐1+/ IL2R+) were isolated by fluorescence‐activated cell sorter (FACS). These three populations expanded with different kinetics in the thymus of irradiated recipient mice after intrathymic transfer. When a high dose of human recombinant IL‐2 (r‐IL‐2) or human recombinant IL‐6
(r‐IL‐6) was administered, r‐IL‐6 accelerated donor Thy‐1+/IL2R+ to differentiate, whereas r‐IL‐2 blocked normal differentiation and expansion of donor Thy‐1‐lo/Thym, but did not
show any significant effect on donor Thy‐1+/IL2R+. Neither r‐IL‐2 nor r‐IL‐6 worked directly on donor Thy‐1‐lo/BM in this transfer system.
Expression of MHC Class II Antigens During Xenopus Development
Authors: Du Pasquier Louis , Flajnik Martin F.
Published: June 2008

Larval and adult forms of the amphibian Xenopus differ in their MHC class II .expression. In
tadpoles, class II epitopes can be detected by monoclonal antibodies only on B cells, macrophages
(whatever their location), spleen reticulum, thymus epithelium, and the pharyngobuccal
cavity. In contrast, all adult T cells express class II on their surface. The transitions in
class II expression occur at metamorphosis and are accompanied by other changes. The skin
is invaded by class II positive dendritic cells, and the skin glands differentiate and also
express class II. The gut, which expressed class II in discrete areas of the embryonic tissue,
becomes invaded with B cells, and its epithelium also becomes class II positive.
Delay of Early B‐Lymphocyte Development by Gamma 2b Immunoglobulin Transgene: Effect on Differentiation‐Specific Molecules
Authors: Denis Kathleen A. , Provost Scott , Witte Owen N. , Brinster Ralph L. , Storb Ursula
Published: June 2008

Mice transgenic for γ2b Ig heavy chain were examined for alterations in B‐cell differentiation
and endogenous Ig gene rearrangement and expression. Fresh bone marrow from these mice
was markedly reduced in BP‐1+ cells and there were small reductions in B220+ and sIg+ cells. A‐MuLV (Abelson murine leukemia virus) transformants from these bone marrow cells
showed little alteration in Ig gene rearrangement and expression when compared to
controls, however. Isolation of the B‐lymphoid compartment from these mice in vitro using
LBMC (lymphoid bone marrow cultures) enabled more detailed characterization of the
effects of the transgene. LBMC derived from γ2b transgenic mice had similar growth
kinetics, but a 4‐5‐week delay in the expression of endogenous mu Ig in comparison to
control cultures. Nucleic acids derived from these early cultures prior to endogenous mu Ig
expression showed reduced Ig JH rearrangements, some sterile mu transcription, low levels
of BP‐1 expression, and virtually undetectable TdT (terminal deoxynucleotidyl transferase)
expression. Thus, this γ2b transgene appears able to affect early B‐lymphocyte development.
Ontogenic Appearance of MHC Class I (B‐F) Antigens During Chicken Embryogenesis
Authors: Dunon D. , Salomonsen J. , Skjødt K. , Kaufman J. , Imhof B. A.
Published: June 2008

Expression of chicken MHC class (B‐F) antigens during ontogeny was determined by
binding of anticlass antibody and appearance of B‐F transcripts by Northern blotting in
chicken organs during embryogenesis until 2 weeks after hatching. MHC class transcripts
first become detectable in day 6.5 of embryogenesis. B‐F cell‐surface expression first
becomes detectable in hemopoietic organs by day 10‑12 of embryogenesis and somewhat
later in nonhemopoietic organs. Flow cytometry analysis of hemopoietic cells throughout
embryogenesis revealed B‐Fhi and B‐F1 cell populations. The percentage of B‐F cells in
spleen and bone marrow decreased around hatching, which could reflect either cell flows in
these organs during this period or the sensitivity of hemopoietic cells to hatching stress.
Characterization of Murine Thymic Stromal‐Cell Lines Immortalized by Temperature‐Sensitive Simian Virus 40 Large T or Adenovirus 5 E1a
Authors: Larsson Lena , Timms Emma , Blight Kenneth , Restall Deborah E. , Jat Parmjit S. , Fisher Amanda G.
Published: June 2008

The heterogeneity of thymic stromal cells is probably related to their role in providing
different microenvironments where T cells can develop. We have immortalized thymic
stromal elements using recombinant retroviral constructs containing a temperature‐sensitive
simian virus 40 (SV40tsA58) large‐T antigen gene or the adenovirus 5 E1a
region linked to the gene coding for resistance to G418. Cell lines containing the
thermolabile large T antigen encoded by SV40 proliferate at the permissive temperature
of 33°C and arrest growth when transferred to the nonpermissive temperature of 39°C.
At the nonpermissive temperature, ts‐derived cell lines are shown to alter their
phenotype but remain metabolically active, as indicated by the inducible expression of
class I and class II MHC antigens. Here we describe the generation of a total of 84
thymic stromal‐cell lines, many of which show distinct morphologic, phenotypic, and
functional properties consistent with fibroblastoid, epithelial, or monocytoid origins.
Several E1a and SV40tsA58‐derived cell lines generated exhibit the epithelial
characteristic of desmosome formation and, in addition, two of these lines (15.5 and
15.18) form multicellular complexes (rosettes) when incubated with unfractionated
thymocytes from syngeneic mice. A single line (14.5) displays very strong nonspecific
esterase activity, suggesting it may represent a macrophagelike cell type. We describe
the generation of stromal cell lines with different properties, which is consistent with the
heterogeneity found in the thymic microenvironment. In addition to documenting this
diversity, these cell lines may be useful tools for studying T‐cell development in vitro
and give access to model systems in which stromal‐thymocyte interactions can be examined.
Phylogeny of Immune Recognition: Processing and Presentation of Structurally Defined Proteins in Channel Catfish Immune Responses
Authors: Vallejo Abbe N. , Miller Norman W. , Clem L. William
Published: June 2008

This work was undertaken to investigate whether or not antigen processing and presentation
are important in channel catfish in vitro secondary immune responses elicited with
structurally defined proteins, namely, pigeon heart cytochrome C (pCytC), hen egg
lysozyme, and horse myoglobin. The use of in
vitro antigen‐pulsed and fixed B cells or
monocytes as antigen presenting cells (APC) resulted in autologous peripheral blood leukocytes
(PBL) responding with vigorous proliferation and antibody production in
vitro. In
addition, several long‐term catfish monocyte lines have been found to function as efficient
APC with autologous but not allogeneic responders. Subsequent separation of the
responding PBL into sIg- (T‐cell‐enriched) and B (sIg+) cell subsets showed that both underwent
proliferative responses to antigen‐pulsed and fixed APC. Moreover, allogeneic cells
used as APC were found to induce only strong mixed leukocyte reactions without specific in
vitro antibody production. Initial attempts at identifying the immunogenic region(s) of the
protein antigens for catfish indicated there are two such regions for pCytC, namely, peptides
66‐80 and 81‐104.
T‐Lymphocyte Subsets in the Embryonic Spleen Undergoing a Graft‐Versus‐Host Reaction
Authors: Fedecka-Bruner Barbara , Vaigot Pierre , Désveaux-Chabrol Jacqueline , Gendreau Marcelle , Kroemer Guido , Dieterlen-Lièvre Françoise
Published: June 2008

Allogeneic immunocompetent T cells injected into chicken embryos induce a graft‐versushost
reaction (GVHR) whose most prominent manifestation is splenic hyperplasia. The
highly inbred CC and CB strains of chickens used here are, respectively, homozygous for
the B4 or B12 MHC haplotypes. By means of a panel of immunological reagents, including
alloantisera and monoclonal antibodies against public domains of the T‐cell receptor, CD4,
CD8, and the inducible interleukin‐2‐receptor light chain (CD25), it is shown that the bulk
of cells in the enlarged spleen are of host origin and do not express markers typical of
mature T or B lymphocytes. Among recipient splenocytes, the quantitatively most important
population consists of TCRαβ
‐TCRγδ
‐CD4‐CD8+CD25+ (TCR0) lymphocytes. Donor cells
encountered in the spleen prevalently exhibit a TCRαβ
+CD4+CD8‐CD25+ phenotype and
proliferate in vivo. The data demonstrate that nonspecific host and potentially specific donorderived
cellular elements contribute to splenomegaly.
Antigen‐Independent Selection of T15 Idiotype During B‐Cell Ontogeny In Mice
Authors: Vakil Meenal , Briles David E. , Kearney John F.
Published: June 2008

Precursors of B cells capable of responding to a T‐independent form of phosphorylcholine
(PC) in splenic focus assays were detected in the spleens of neonatal mice as early as 4 days
after birth. The earliest anti‐PC B cells were T15-. T15+ foci‐forming B cells were first
detected 6 days after birth and expanded rapidly to constitute greater than 80% of the total
PC‐specific foci by day 10. Injection of heat‐killed S. pneumoniae (R36A) into neonatal mice
resulted in priming of the antibody response to PC, with an idiotype profile reflecting that
of precursors of foci‐forming B cells at the time of antigen administration. Priming of 2‐dayold
mice with 2 X106 and 2 X107 R36A induced a five‐ and ten‐fold increase in the antibody
response to phosphorylcholine 6 to 8 weeks later. However, only 10 to 15% of the serum
antibodies expressed the normally dominant T15 idiotype. Doses below 2 x105 R36A showed
no detectable priming activity. PC‐specific hybridomas derived from mice injected with
2 X107 R36A 2 days after birth lacked the idiotypic and molecular characteristics typical of
T15+ antibodies. Antibodies to phosphorylcholine, raised by immunization of 6‐week‐old
mice are normally protective against pneumococcal infection. However, serum antibodies
from mice treated with R36A 2 days after birth and responding to phosphorylcholine
following challenge with R36A at 6 weeks of age failed to protect against deliberate infection
with virulent S. pneumoniae. These observations imply that the antigen phosphorylcholine
does not play a role in the selective expansion and dominant expression of the T15 idiotype.
Different Subpopulations of Developing Thymocytes are Associated with Adherent (Macrophage) or Nonadherent (Dendritic) Thymic Rosettes
Authors: Shortman Ken , Vremec David
Published: June 2008

Thymic rosettes (ROS), structures consisting of thymic lymphoid cells attached to a
central stromal cell, were isolated from mouse thymus by collagenase digestion and
unit‐gravity elutriation. The ROS were then separated into those where the stromal cells
were either macrophage‐like (M‐ROS) or dendritic cell‐like (D‐ROS), on the basis of the
differences in adherence properties or in the level of MAC‐1 surface antigen. The ROS
were then dissociated and the thymocyte content analyzed by immunofluorescent
staining and flow cytometry. M‐ROS and D‐ROS differed in thymocyte composition,
although the major component of both was the CD4+CD8+ cortical thymocyte. D‐ROS
were enriched in thymocytes expressing high levels of surface T‐cell antigen receptor
(TcR) and the associated CD3 complex, and these included both CD4+CD8+CD3++ and
CD4-CD8+CD3++ mature thymocytes. M‐ROS were enriched in CD4-CD8- thymocytes
and had a reduced content of thymocytes expressing high TcR‐CD3 levels; they
nevertheless contained some mature thymocytes, but only of the CD4+CD8-CD3++ category. Several lines of evidence indicated that the mature thymocytes in ROS were
cells recently formed in the cortex, and were not from the medullary pool. ROSassociated
mature thymocytes expressed lower levels of H‐2K than free, mature
thymocytes. The CD4+CD8+CD3++ subpopulation, believed to be a developmental
intermediate between cortical thymocytes and mature T cells, was present in both ROS
populations. Further, late intermediates leading to both mature T‐cell categories were
evident in D‐ROS, but only those leading to CD4+CD8-CD3++ T cells were evident in M‐ROS.
The results are compatible with a role for ROS in TcR‐specificity selection and in
the final maturation steps in the thymic cortex.
Comparison of Mouse Ly5a and Ly5b Leucocyte CommonAntigen Alleles
Authors: Zebedee Suzanne L. , Barritt Diana S. , Raschke William C.
Published: June 2008

The family of leucocyte common antigen (LCA) transmembrane glycoproteins is
expressed in most hematopoietic cells. Molecular isoforms of the LCA molecule are
generated by alternative splicing of a single gene encoded on the murine chromosome 1.
Three LCA alleles with different antigenic reactivities have been identified in inbred
mouse strains. To investigate the divergence between alleles, cDNA clones to the SJA
(Ly5a) LCA gene have been isolated and sequenced. A comparison of this information to
the Ly5b allele sequence identifies 12 allele‐specific nucleotide changes. These base
substitutions correspond to five amino‐acid changes within the extracellular domain of
the LCA molecule. These amino‐acid differences are clustered in a region that also
contains the greatest divergence between mouse and rat LCA sequences. Thus, these
two mouse LCA alleles exhibit a pattern of sequence conservation that mimics that
found over a much broader scale of evolution. Analysis of antigenicity profiles for each
of the allelic sequence changes reveals three molecular domains of altered antigenicity
that could account for observed serological differences between the two alleles.
Sequence information from the 5′ end of the Ly5a LCA gene, generated using
polymerase chain‐reaction techniques on genomic DNA, reveals eight additional
nucleotide differences between the Ly5a and Ly5b alleles.
Expression of a Leukocyte‐Specific Antigen During Ontogeny in Xenopus Laevis
Authors: Smith Paula B. , Turpen James B.
Published: June 2008

The monoclonal antibody CL21 recognizes a determinant present on the surface of
leukocytes, but not on erythrocytes or nonhemopoietic tissue. The CL21 antigen was
first expressed at 48 hr of development at 20°C (stage 28) on embryonic cells cultured
from lateral plate mesoderm. Based on immunofluorescence staining and flow
cytometric analysis, the distribution of fluorescence intensity of larval thymocytes and
splenocytes was unimodal. Distributions of dull and bright cells were detected in both
adult thymocytes and splenocytes. These different subpopulations appeared during the
late perimetamorphic period. Adult splenocytes were metabolically activated when
cultured in the presence of mAb CL21 bound to a substrate but not in the presence of
mAb CL21 in suspension. Immunoprecipitation and SDS‐PAGE under nonreducing
conditions revealed that a single 180‐kD molecule was expressed on thymocytes.
Analysis of splenocytes demonstrated the presence of two molecules having similar
molecular mass that resolved to a single band under reducing conditions.
Characterization of RT6‐Bearing Rat Lymphocytes. II. Developmental Relationships of RT6‐ and RT6+T Cells
Authors: Mojcik Christopher F. , Greiner Dale L. , Goldschneider Irving
Published: June 2008

The derivation of RT6+ T cells from postthymic RT6‐ T cells in weanling rats was formally
demonstrated by the intravenous transfer (“parking”) of highly purified populations of RT6‐ lymph node T cells into thymectomized, irradiated, and bone‐marrow‐reconstituted (TXBM)
RT6+ and RT7 alloantigen‐disparate recipients. Parallel experiments in irradiated and bonemarrow‐
reconstituted rats, and in rats whose RT6+ T cells had been depleted by injection of
DS4.23 anti‐RT6.1 mAb, suggested that the transit time between the pre‐RT6+ and the RT6+ T‐cell compartments approximated 4‐5 days. A more precise estimate of the transit time was
made by linear regression analysis of the generation of RT6+ T cells in rats that were treated
with DS4.23 mAb at timed intervals after thymectomy. This study indicated that 50% of the
pre‐RT6 T cells differentiated into RT6+ cells within 4 days, 75% within 8 days, and more
than 90% within 16 days.Despite the apparent absence of pre‐RT6‐ T cells 3 weeks after thymectomy, numerous
RT6‐ T cells persisted for at least 10 weeks in thymectomized rats, even after treatment with
DS4.23 mAb. Moreover, these RT6+ T cells failed to generate RT6+ T cells after transfer into adoptive hosts. Quantitative and phenotypic analyses indicated that this population of “true”
RT6‐ T cells: (1) constitutes approximately 50% of the total RT6‐ T cells normally found in
control rats; (2) contains CD4 and CD8 subsets; (3) expresses both the CD5 pan‐T‐cell
antigen (which is absent from NK cells) and the R73 α/β TCR constant‐region determinant; and (4) lacks sIgM.Hence, the present results indicate that the “true” RT6‐ and the RT6+ T‐cell subsets have
stable antigenic phenotypes and represent developmentally discrete populations of postthymic
cells in normal rats. This is supported by associated phenotypic and functional
studies that suggest that the “true” RT6‐T‐cell subset contains antigenically naive and/or autoreactive clonotypes, whereas the RT6+ T‐cell subset contains memory and/or regulatory
cells. It remains to be determined whether the “true” RT6‐ and the RT6+ subsets represent separate lineages of T cells or a single lineage at different stages of activation or maturation.
Functional Relationship Between T15 and J558 Idiotypes in BALB/c Mice
Authors: Vakil Meenal , Kearney John F.
Published: June 2008

In inbred strains of mice, antiphosphorylcholine (PC) and anti‐α1,3 dextran (DEX). antibodies
are structurally distinct from each other and have been shown to exhibit noncrossreactive
antigen binding and idiotypic specificities. However, the prototype anti‐PC and
anti‐DEX antibodies, TEPC15 and J558, respectively, were shown to be connected via a
common autoantiidiotypic monoclonal antibody isolated from newborn BALB/c mice. The
capacity of various monoclonal anti‐PC and anti‐DEX antibodies as well as the antigens PC
and DEX to modulate T15 and J558 idiotypes in BALB/c mice was tested by their administration
to newborn mice. Anti‐PC antibodies of the .T15 idiotype injected into 2‐4‐day‐old
mice, at a time when T15 anti‐PC precursors develop in BALB/c mice, suppressed the anti‐
PC response of these mice at 6 weeks of age. Similarly, J558 antibodies injected into 8‐12‐day‐old mice, at a time when J558 precursors normally develop, suppressed the response to
DEX. As a further demonstration of this connectivity, the injection of J558 into 4‐day‐old
mice led to a down modulation of T15 idiotype, whereas both T15 and a minor idiotypeexpressing
antibody M167 when injected into 8‐12‐day‐old mice caused a reduction in
expression of the J558 idiotype. As predicted from in vitro analysis, injection of anti‐PC
antibodies of the M167 idiotype 2 to 4 days after birth enhanced the subsequent response to
PC. However, anti‐PC antibodies expressing another minor M603 idiotype did not affect the
PC. response. The results parallel the in vitro enhancement of M167 antibodies but not M603
on T15 binding to antiidiotype in vitro. Similarly, anti‐DEX antibodies expressing the M104E
idiotype had no detectable effects on the capacity to respond to PC or DEX or on the expression
of T15 and J558 idiotypes as adults. Exposure of newborn mice to PC led to a dramatic
reduction in the response to DEX as adults, whereas exposure to DEX at this stage of
development had no effect on response to PC as adults. Collectively, these observations provide
evidence for a complex functional connectivity between T15 and J558 idiotype‐bearing B
cells during ontogeny and extend our previous observations that development of these idiotypes
is regulated by idiotype‐directed interactions between B cells or their immunoglobulin
products.
Developmental Expression of IL‐2‐Receptor Light Chain (CD25) in the Chicken Embryo
Authors: Fedecka-Bruner Barbara , Penninger Josef , Vaigot Pierre , Lehmann Anne , Martínez-A. Carlos , Kroemer Guido
Published: June 2008

Thymocyte differentiation obeys the same fundamental principles in mammals as in avian
species. This parallelism does not only affect the developmentally controlled acquisition of
CD3, 4, 8, and TcR isotype expression, but also concerns CD25, the light chain of the interleukin‐2 receptor (IL‐2R). On chicken thymocytes, surface CD25, which is recognized by the
monoclonal antibody INN Ch16, is first observed during day 11 of embryonic life, and peaks
at day 14, when it is expressed by about one‐third of all lymphoid cells. CD25 is found on
subsets of all ,thymocyte populations as defined by TcRαβ, TcRγδ, 2, CD4, and CD8 expression,
cortical or medullary localization, and is also present on a subset of intrathymic nurse‐cell
lymphocytes. These findings suggest phylogenetic conservation of the IL‐2/IL‐2R‐triggered
differentiation pathway previously described for mammalian species, thus under‐lining
its probable functional importance.
Murine T‐Lymphomas Corresponding to the ImmatureCD4-8+ Thymocyte Subset
Authors: Richie Ellen R. , Mcentire Brenda B. , Coghlan Lezlee , Poenie Martin
Published: June 2008

N‐methyl‐N‐nitrosourea induces murine CD4-8+ T‐lymphomas that express high levels
of J11d and low levels of CD5 antigens, a phenotype characteristic of immature CD4-8+
thymocytes. This assignment is supported by the fact that CD4-8+ lymphoma cell lines
acquire CD4 expression after intrathymic (i.t.) transfer, a finding consistent with the
established precursor potential of the normal immature CD4-8+ subset. CD4+8+ lymphomas recovered after i.t. transfer maintain a CD4+8+ phenotype in long‐term culture. Northern blot analyses reveal that CD4 expression is regulated at the
transcriptional level in immature CD4-8+ and CD4+8+ cell lines. CD4-8+ lymphomas
express low levels of functional CD3/TCR complexes that mediate intracellular Ca2+
mobilization in response to CD3 or α/β‐TCR monoclonal antibody. These data suggest
that the immature CD4-8+ subset contains cells capable of undergoing TCR‐mediated
signaling and selection events. In contrast to normal immature CD4-8+ cells, which
comprise a heterogeneous and transient subset, the CD4-8+ lymphoma lines provide
stable, monoclonal models of the immature CD4-8+ stage of thymocyte development.