An evaluation of semidistributed-pipe-network and distributed-finite-difference models to simulate karst systems.

Several different approaches have been developed to model the specific characteristics of karst aquifers, taking account of their inherent complex spatial and temporal heterogeneities. This paper sets out the development of a semidistributed modelling approach for applications in an Irish karst context using urban drainage software. The models have proven to be very useful for different studies, with examples given for the ecohydrology of ephemeral karst lakes, extreme groundwater-flood alleviation, karst network investigation, submarine groundwater discharge, and quantification of different recharge and flow components. The limitations of the approach are also highlighted, in particular not being able to simulate diffuse infiltration and flow paths explicitly across the groundwater catchment. Hence, a more distributed, finite-difference modelling approach using MODFLOW Unstructured Grid (USG) with the newly developed Connected Linear Network (CLN) process is then compared against the semidistributed approach on the same karst catchment. Whilst it has proven difficult to achieve the same levels of model performance in simulating the spring flows in the distributed model compared to the semidistributed model, the ability to interrogate the flow paths at any point on the three-dimensional aquifer is demonstrated, which can give new insights into flows (and potential contaminant transport) through such complex systems. The influence of the proximity of highly transmissive conduits on the flow dynamics through the much-lower transmissive matrix cells in which the network is embedded has been particularly investigated.

Plusieurs approches différentes ont été développées pour modéliser les caractéristiques spécifiques des aquifères karstiques, prenant en compte leurs hétérogénéités spatiales et temporelles associées à leur complexité intrinsèque. Cet article présente le développement d'une approche de modélisation semi-distribuée appliquée à un contexte karstique irlandais en utilisant un logiciel de drainage urbain. Ces modèles se sont avérés très utiles pour différentes études, avec des exemples appliqués à l'écohydrologie de lacs karstiques éphémères, l'atténuation de crues extrêmes liées aux eaux souterraines, à l'étude du réseau karstique, à la décharge des sources sous-marines et à la quantification des différentes composantes aussi bien de la recharge que du débit. Les limites de cette approche sont aussi mises en évidence, avec en particulier l'incapacité de simuler l'infiltration diffuse et les voies d'écoulement de manière explicite au sein du bassin d'alimentation d'eaux souterraines. Par conséquent, une approche de modélisation plus distribuée aux différences finies utilisant le logiciel MODFLOW avec une grille non structurée (USG) intégrant le processus récemment développé de réseau linéaire connecté (CLN) est ensuite comparée à l'approche semi-distribuée appliquée au même bassin karstique. Alors qu'il s'est avéré difficile d'atteindre les mêmes niveaux de performance du modèle concernant la simulation du débit à la source à l'aide du modèle distribué en comparaison au modèle semi-distribué, la possibilité d'examiner les voies d'écoulement en tout point de l'aquifère en 3D est démontrée, ce qui peut donner de nouvelles connaissances sur les écoulements (et le transport potentiel de contaminants) au sein de tels systèmes complexes. L'influence de la proximité de conduits hautement transmissifs sur les écoulements dynamiques au travers des cellules de transmissivité plus faible de la matrice au sein de laquelle le réseau est intégré, a été particulièrement étudiée.

Se han elaborado varios enfoques diferentes para modelar las características específicas de los acuíferos kársticos, teniendo en cuenta sus complejas y propias heterogeneidades espaciales y temporales. En el presente documento se expone la elaboración de un enfoque de modelización semidistribuido para aplicaciones en un contexto kárstico de Irlanda utilizando programas informáticos de drenaje urbano. Los modelos han demostrado ser muy útiles para diferentes estudios, y se dan ejemplos para la ecohidrología de los lagos kársticos efímeros, la mitigación de las inundaciones extremas de aguas subterráneas, la investigación de redes kársticas, la descarga submarina de aguas subterráneas y la cuantificación de diferentes componentes de la recarga y el flujo. También se ponen de relieve las limitaciones del enfoque, en particular el hecho de no poder simular explícitamente la infiltración difusa y las trayectorias de flujo a través de la cuenca de captación de aguas subterráneas. Por lo tanto, un enfoque de modelización de diferencias finitas distribuidas utilizando la red no estructurada (USG) de MODFLOW con el proceso de la Red Lineal Conectada (CLN) recientemente desarrollado se compara entonces con el enfoque semidistribuido en la misma cuenca kárstica. Si bien se ha demostrado que es difícil lograr los mismos niveles de rendimiento del modelo en la simulación de los flujos de manantiales en el modelo distribuido en comparación con el modelo semidistribuido, se demuestra la capacidad de interrogar las trayectorias de los flujos en cualquier punto del acuífero tridimensional, lo que puede dar nuevos conocimientos sobre los flujos (y el transporte de contaminantes potenciales) a través de sistemas tan complejos. Se ha investigado en particular la influencia de la proximidad de conductos altamente transmisivos en la dinámica de los flujos a través de las células de la matriz transmisiva, mucho más bajas, en las que está incorporada la red.

Diversas abordagens diferentes foram desenvolvidas para modelar as características específicas dos aquíferos cársticos, levando em consideração suas complexas heterogeneidades espaciais e temporais inerentes. Este artigo apresenta o desenvolvimento de uma abordagem de modelagem semidistribuída para aplicações em um contexto cárstico irlandês usando software de drenagem urbana. Os modelos provaram ser muito úteis para diferentes estudos, com exemplos dados para a ecohidrologia de lagos cársticos efêmeros, alívio de inundações subterrâneas extremas, investigação de rede cárstica, descarga de água subterrânea submarina e quantificação de diferentes componentes de recarga e fluxo. As limitações da abordagem também são destacadas, em particular não ser capaz de simular infiltração difusa e caminhos de fluxo explicitamente através da captação de água subterrânea. Portanto, uma abordagem de modelagem de diferenças finitas, mais distribuída, usando MODFLOW Unstructured Grid (USG) com o processo de Rede Linear Conectada (RLC) recém-desenvolvido é então comparada com a abordagem semidistribuída na mesma bacia cárstica. Embora tenha se mostrado difícil alcançar os mesmos níveis de desempenho do modelo na simulação dos fluxos de nascente no modelo distribuído em comparação com o modelo semidistribuído, a capacidade de interrogar os caminhos de fluxo em qualquer ponto do aquífero tridimensional é demonstrada, o que pode dar novas percepções sobre os fluxos (e o transporte potencial de contaminantes) por meio de tais sistemas complexos. A influência da proximidade de condutos altamente transmissivos na dinâmica do fluxo através das células da matriz transmissiva muito inferior nas quais a rede está inserida foi investigada particularmente.

Integrated demultiplexing and amplification of coherent optical combs.

The explosive growth of the internet during the last few decades has been enabled by two complementary innovations in optical communications: the use of multiple optical channels within a single optical fibre, and the increase in the bandwidth of individual channels to hundreds of Gbps. Further increases in overall bandwidth look to be provided by more spectrally efficient optical superchannels that use coherent sub-carriers generated using optical orthogonal frequency division multiplexing (OFDM). Yet, a cost effective way of generating these signals has not been demonstrated. One crucial, but missing piece is an effective means to separate the closely frequency spaced optical sub-carriers from the coherent optical comb before placing information on each sub-carrier, and thus creating the OFDM signal. Here, we demonstrate a flexible strategy implemented in a compact photonic integrated circuit (PIC) that is used to separate and amplify these sub-carriers using on-chip injection locking.

Can Early Changes in Vital signs Predict Duration of Antibiotic Therapy in Suspected Neonatal Sepsis?

Aims Suspected sepsis remains a leading causes of Neonatal Intensive Care Unit admission, with infants often receiving 48-72 hours of empirical antibiotic therapy. Early in treatment it is difficult to predict infants who will require prolonged antibiotic therapy. Our aim was to assess if vital sign measurements in the initial period of treatment can predict those neonates requiring prolonged antibiotic therapy in term and late-preterm infants. Methods Data was retrospectively collected over 1 year on neonates admitted to our institute for antibiotics. Infants were classified as standard (<48hours duration) or prolonged (>48hours duration) antibiotic therapy. Results Respiratory rate on admission and 12 hours after initiation of therapy correlated significantly with duration of antibiotic therapy and infants requiring prolonged therapy were more likely to have one or more abnormal vital signs 12 hours after initiation of treatment (p<0.05). Conclusion Respiratory rate shows a weak positive correlation with antibiotic duration. Infants requiring prolonged therapy were more likely to have abnormal vital signs 12 hours after initiating antibiotic therapy. Changes in vital signs maybe useful in detecting infants who will require prolonged antibiotic therapy.

Mood, body image, fear of kidney failure, life satisfaction, and decisional stability following living kidney donation: Findings from the KDOC study.

Prior studies demonstrate that most living kidney donors (LKDs) report no adverse psychosocial outcomes; however, changes in psychosocial functioning at the individual donor level have not been routinely captured. We studied psychosocial outcomes predonation and at 1, 6, 12, and 24 months postdonation in 193 LKDs and 20 healthy controls (HCs). There was minimal to no mood disturbance, body image concerns, fear of kidney failure, or life dissatisfaction, indicating no incremental changes in these outcomes over time and no significant differences between LKDs and HCs. The incidence of any new-onset adverse outcomes postdonation was as follows: mood disturbance (16%), fear of kidney failure (21%), body image concerns (13%), and life dissatisfaction (10%). Multivariable analyses demonstrated that LKDs with more mood disturbance symptoms, higher anxiety about future kidney health, low body image, and low life satisfaction prior to surgery were at highest risk of these same outcomes postdonation. It is important to note that some LKDs showed improvement in psychosocial functioning from pre- to postdonation. Findings support the balanced presentation of psychosocial risks to potential donors as well as the development of a donor registry to capture psychosocial outcomes beyond the mandatory 2-year follow-up period in the United States.

Direct and Indirect Costs Following Living Kidney Donation: Findings From the KDOC Study.

Some living kidney donors (LKDs) incur costs associated with donation, although these costs are not well characterized in the United States. We collected cost data in the 12 mo following donation from 182 LKDs participating in the multicenter prospective Kidney Donor Outcomes Cohort (KDOC) Study. Most LKDs (n = 167, 92%) had one direct cost or more following donation, including ground transportation (86%), health care (41%), meals (53%), medications (36%), lodging (23%), and air transportation (12%). LKDs missed 33 072 total work hours, 40% of which were unpaid and led to $302 175 in lost wages (mean $1660). Caregivers lost $68 655 in wages (mean $377). Although some donors received financial assistance, 89% had a net financial loss in the 12-mo period, with one-third (33%) reporting a loss exceeding $2500. Financial burden was higher for those with greater travel distance to the transplant center (Spearman's ρ = 0.26, p < 0.001), lower household income (Spearman's ρ = -0.25, p < 0.001), and more unpaid work hours missed (Spearman's ρ = 0.52, p < 0.001). Achieving financial neutrality for LKDs must be an immediate priority for the transplant community, governmental agencies, insurance companies, nonprofit organizations, and society at large.

Monolithically integrated low linewidth comb source using gain switched slotted Fabry-Perot lasers.

A monolithically integrated low linewidth optical comb is demonstrated by gain switching of a three-section laser device. The device consists of a slave and master section separated by a shared slotted mirror section. Wavelength tunability has been demonstrated by varying the electrical bias of each section. The number of comb lines is shown to almost double with the addition of optical injection from the master section into the slave. The unmodulated device has a full width half max linewidth of ∼ 500 kHz, while the comb line set were measured to be ∼ 600 kHz, with little degradation as a result of gain switching. The FSR (free spectral range) of the demonstrated comb is 4 GHz, which is tunable within the bandwidth of the device, with a central wavelength of 1580.3 nm.

Predonation Direct and Indirect Costs Incurred by Adults Who Donated a Kidney: Findings From the KDOC Study.

Limited information exists on the predonation costs incurred by eventual living kidney donors (LKDs). Expenses related to completion of the donation evaluation were collected from 194 LKDs participating in the multi-center, prospective Kidney Donor Outcomes Cohort (KDOC) Study. Most LKDs (n = 187, 96%) reported one or more direct costs, including ground transportation (80%), healthcare (24%), lodging (17%) and air transportation (14%), totaling $101 484 (USD; mean = $523 ± 942). Excluding paid vacation or sick leave, donor and companion lost wages totaled $35 918 (mean = $187 ± 556) and $14 378 (mean = $76 ± 311), respectively. One-third of LKDs used paid vacation or sick leave to avoid incurring lost wages. Few LKDs reported receiving financial support from the transplant candidate (6%), transplant candidate's family (3%), a nonprofit organization (3%), the National Living Donor Assistance Center (7%), or transplant center (3%). Higher total costs were significantly associated with longer distance traveled to the transplant center (p < 0.001); however, total costs were not associated with age, sex, race/ethnicity, household income, marital status, insurance status, or transplant center. Moderate predonation direct and indirect costs are common for adults who complete the donation evaluation. Potential LKDs should be advised of these possible costs, and the transplant community should examine additional strategies to reimburse donors for them.

10 Gb/s InP-based Mach-Zehnder modulator for operation at 2 µm wavelengths.

We report on the first InP-based Mach-Zehnder modulator (MZM) employing quantum-confined Stark effect (QCSE) for operation around 2000 nm. The polarization sensitive device is based on 15 compressively strained quantum wells and achieves an electro-optic (EO) bandwidth of at least 9 GHz, with a DC extinction ratio of ~9 dB, and a V(π)L ~9.6 V.mm. We demonstrate back-to-back communication with a 10 Gb/s pseudo-random bit sequence (PRBS) of length 2(7)-1 at a wavelength around 2000 nm.

Dense WDM transmission at 2 µm enabled by an arrayed waveguide grating.

We show, for the first time, dense WDM (8×20 Gbit/s) transmission at 2 µm enabled by advanced modulation formats (4-ASK Fast-OFDM) and the development of key components, including a new arrayed waveguide grating (AWGr) at 2 µm. The AWGr shows -12.8±1.78 dB of excess loss with an 18-dB extinction ratio and a thermal tunability of 0.108 nm/°C.

On-chip optical phase locking of single growth monolithically integrated Slotted Fabry Perot lasers.

This work investigates the optical phase locking performance of Slotted Fabry Perot (SFP) lasers and develops an integrated variable phase locked system on chip for the first time to our knowledge using these lasers. Stable phase locking is demonstrated between two SFP lasers coupled on chip via a variable gain waveguide section. The two lasers are biased differently, one just above the threshold current of the device with the other at three times this value. The coupling between the lasers can be controlled using the variable gain section which can act as a variable optical attenuator or amplifier depending on bias. Using this, the width of the stable phase locking region on chip is shown to be variable.

Hydraulic conductivity assessment of falling head percolation tests used for the design of on-site wastewater treatment systems.

The suitability of a location for an on-site wastewater treatment process (for areas which lack access to centralised wastewater treatment systems) requires an assessment of the permeability of the soil into which the effluent will be discharged. In many jurisdictions this is determined using some type of in-situ percolation test. Falling head percolation tests, which give a value of percolation time (PT) that is empirically related to the notion of hydraulic conductivity, are widely used as they are relatively simple to carry out, but the test does not have a sound theoretical framework and test methods are not standardised internationally. In comparison, the saturated hydraulic conductivity of a soil obtained from a constant head well permeameter test is independent of test conditions, and so is a more suitable metric for design. A database of over 900 falling head tests carried out across a range of different subsoil types in Ireland has been collated, all with the inherent limitations of the existing regulative framework regarding the percolation test and soil texture assessment. These tests were then modelled using Hydrus 2-D numerical modelling simulations to determine equivalent field saturated hydraulic conductivity (Kfs) values and thereby provide a correlation with PT values across the range of subsoil conditions. In addition, falling head tests have been carried out in parallel to constant head permeameter tests in the field and compared against the relationship derived from the broad dataset of simulated results. This revealed an optimal solution by which to determine Kfs from the field permeameter test (using parameters recommended for most structured soils from clays to loams). The trendline based on Irish data was also compared against more generic formulations of the relationship between PT, and Kfs and shown to match closely, particularly the Reynolds (2016) 'unified' methodology. Finally, the Irish threshold PT limits for on-site wastewater treatment have been converted to Kfs values and compared against other international standards.

T cell tolerance to non-H-2-encoded stimulatory alloantigens is induced intrathymically but not prethymically.

The present report has evaluated the differentiation compartment in which T cells are tolerized to non-major histocompatibility complex (MHC)-encoded minor lymphocyte-stimulating locus (MLS) alloantigens. It was observed that T cell precursors are not tolerized prethymically to MLS alloantigens but are tolerized intrathymically and postthymically to MLS alloantigens. The failure of prethymic T cells to be tolerized indicates either that T cell precursors are unable to be tolerized to MLS alloantigens or that cells in the prethymic compartment are unable to induce MLS-specific tolerance. In either case, these results demonstrate that the thymus is the initial site in which T cell tolerance to MLS alloantigen is induced. The present results also demonstrate a striking disparity in the reactivity of thymocytes to MHC and MLS alloantigens expressed in the extrathymic host through which their precursors had migrated. In the experimental mice constructed for these studies, intrathymic T cells were tolerant to the MHC alloantigens but were reactive to the MLS alloantigens expressed by the extrathymic host. This observation is consistent with the concept that T cell precursors may be tolerized to MHC alloantigens at an earlier point in their differentiation than they are tolerized to non-MHC-encoded MLS alloantigens.

Tolerance of thymocytes to allogeneic I region determinants encountered prethymically. Evidence for expression of anti-Ia receptors by T cell precursors before their entry into the thymus.

The present study has assessed whether precursor T cells express receptors specific for the recognition of allogeneic I region-encoded determinants before their entry into the thymus. Because the ability of thymocytes to proliferate in response to allogeneic stimulator cells was shown to primarily result from the recognition of allogeneic I region determinants, thymocytes must already express anti-Ia receptors. In contrast, the expression of anti- Ia receptors by functionally immature thymocyte precursors could not be directly assessed by mixed lymphocyte reaction reactivity. However, expression of anti-Ia receptors by thymocyte precursors could be assessed by their ability to be specifically tolerized by the allogeneic Ia determinants that they encountered during their differentiation. To determine whether T cell precursors could specifically recognize and be tolerized to allogeneic Ia determinants expressed prethymically, thymus- engrafted radiation bone marrow chimeras were constructed [A {arrow} A x B (Tx + A Thy)] such that strain A T cells would be differentiating within a syngeneic strain A thymus but would have been previously exposed to the allogeneic strain B Ia determinants of the irradiated A x B host. The strain A thymocytes from these experimental animals were indeed tolerant to the extrathymic allogeneic strain B Ia determinants expressed by the irradiated host. Such tolerance was not mediated by detectable suppression and was not explained by the presence intrathymically of extrathymic allogeneic Ia determinants. Thus, these results suggest that T cell precursors can be specifically tolerized entry into the thymus. In addition, the failure to detect the generation of thymocytes with specificity for the allogeneic Ia determinants of the irradiated host, which were not deleted prethymically, argues that novel anti-allo Ia receptor specificities are not generated intrathymically.

CD4+ T cells that express high levels of CD45RB induce wasting disease when transferred into congenic severe combined immunodeficient mice. Disease development is prevented by cotransfer of purified CD4+ T cells.

Purified CD4+ lymph node T cells were sorted into two populations on the basis of their expression of CD45RB (CD45RBhi and CD45RBlo) and injected into congenic severe combined immunodeficient (SCID) mice. After a period of time that was dependent on the number of cells injected, the SCID mice that received CD45RBhi/CD4+ T cells developed a wasting disease that was not seen in SCID mice that received the CD4+/CD45RBlo cells or whole lymph node cells. At death, SCID mice that received the CD4+/CD45RBhi cells had increased spleen and lymph node cellularity compared with normal SCID mice and SCID mice that received the CD4+/CD45RBlo T cells. The spleen and lymph node contained CD4+ cells and neither CD8+ nor surface immunoglobulin M-positive cells, plus a population of cells that did not express any of those markers. At necropsy, the SCID mice that received the CD4+/CD45RBhi cells had significant hyperplasia of the intestinal mucosa with significant lymphoid cell accumulation in the lamina propria. Interestingly, mice that received mixtures of whole lymph node or purified CD4+ cells with CD4+/CD45RBhi cells did not develop weight loss, indicating that the unseparated CD4+ population contained cells that were capable of regulating the reactivity of the CD4+/CD45RBhi cells.

Role of the major histocompatibility complex in T cell activation of B cell subpopulations Lyb-5+ and Lyb-5- B cell subpopulations differ in their requirement for major histocompatibility complex-restricted T cell recognition.

This report has examined the requirements for T helper (T(H)) cell recognition of major histocompatibility complex (MHC) determinants expressed by B cells for the activation of unprimed Lyb-5(+) and Lyb-5(-) B cell subpopulations . The generation of primary T(H) cell-dependent plaque-forming cell responses in vitro microculture required the presence of Lyb-5(+) B cells because B cell populations that were deprived, either genetically or serologically, of the Lyb-5(+) subpopulation were not activated in these responses. Cell-mixing experiments in which A X B {arrow} A chimeric T(H) cells were mixed with purified populations of parental accessory cells and parental B cells demonstrated that the in vitro activation of Lyb-5(+) B cells did not require T(H) cell recognition of B cell MHC determinants, although it did require T(H) cell recognition of accessory cell MHC determinants . In contrast to the failure of Lyb-5(-) B cells to be activated in primary T(H) cell-dependent responses in vitro microculture, isolated populations of Lyb-5(-) B cells were triggered by T(H) cells in vivo in short-term adoptive transfer experiments . By the use of A X B {arrow} A chimeric T(H) cells and parental strain B adoptive hosts, it was possible in vivo to distinguish genetically restricted T(H) cell recognition of B cells from genetically restricted T(H) cell recognition of accessory cells. Similar to the results obtained in vitro, the activation in vivo of unfractionated (Lyb-5(+) plus Lyb-5(-)) B cell populations did not require T(H) cell recognition of B cell MHC determinants . In contrast, in the same in vivo responses activation of isolated populations of Lyb-5(-) B cells did require T(H) cell recognition of B cell MHC determinants. The most straightforward interpretation of these experiments is that T(H) cell recognition of B cell MHC determinants is required for the activation of Lyb-5(-) B cells but is not required for the activation of Lyb-5(+) B cells . To better understand why T(H) cell activation of one B cell subpopulation is genetically restricted, whereas activation of another subpopulation is not, the response of Lyb-5(+) and Lyb-5(-) B cells to the soluble activating factors present in concanavalin A-induced spleen cell supernates (Con A SN) was examined. It was observed that Lyb-5(-) B cells, as opposed to Lyb-5(+) B cells, were unable to respond in microculture to the nonspecific T(H) cell- activating factors present in Con A SN, even though they were able to nonspecifically respond under the same conditions to trinitrophenyllipopolysaccharide. It was observed that the ability of B cell subpopulations to respond to nonspecific soluble T cell factors paralleled their ability to be activated by T(H) cells in a genetically unrestricted manner. Thus, the present experiments demonstrate that activation by T(H) cells of Lyb-5(-) B cells is MHC restricted, whereas activation of Lyb-5(+) B cells is not. These experiments suggest that one possible explanation for such differences is that activation of Lyb-5(+) B cells does not require direct interaction with T(H) cells because they can be activated by soluble activation signals that T(H) cells secrete.

Interleukin 10 and interferon gamma regulation of experimental Trypanosoma cruzi infection.

Studies were undertaken to determine whether interleukin 10, (IL-10) a cytokine shown to inhibit interferon gamma (IFN-gamma) production, was involved in Trypanosoma cruzi infections in mice. Exogenous IFN-gamma protects mice from fatal infection with T. cruzi. Furthermore, resistant B6D2 mice developed fatal T. cruzi infections when treated with neutralizing anti-IFN-gamma monoclonal antibody (mAb). Thus, endogenous as well as exogenous IFN-gamma is important in mediating resistance to this parasite. Because both T. cruzi-susceptible (B6) and -resistant (B6D2) mouse strains produced IFN-gamma during acute infection, we looked for the concomitant production of mediators that could interfere with IFN-gamma-mediated resistance to T. cruzi. We found that IL-10-specific mRNA was produced in the spleens of mice with acute T. cruzi infections. In addition, spleen cell culture supernatants from infected B6 mice, and to a lesser extent B6D2 mice, elaborated an inhibitor(s) of IFN-gamma production. This inhibitor(s) was neutralized by anti-IL-10 mAb. These experiments demonstrated the production of biologically active IL-10 during T. cruzi infection. In further studies in vitro, it was shown that IL-10 blocked the ability of IFN-gamma to inhibit the intracellular replication of T. cruzi in mouse peritoneal macrophages. Thus, in addition to its known ability to inhibit the production of IFN-gamma, IL-10 (cytokine synthesis inhibitory factor), may also inhibit the effects of IFN-gamma. These experiments demonstrate that IL-10 is produced during infection with a protozoan parasite and suggest a regulatory role for this cytokine in the mediation of susceptibility to acute disease.

Molecular cloning and biological characterization of a novel murine lymphoid growth factor.

Using a bioassay consisting of the proliferation of a murine B cell line, a cDNA of a gene whose product supports the growth of that cell line was isolated from a thymic stromal cell line. This factor, termed thymic stromal lymphopoietin (TSLP), is a protein of 140 amino acids. The gene encoding TSLP was mapped to murine chromosome 18. Purified recombinant TSLP supported the growth of pre-B cell colonies in vitro, but had no myelopoietic activity. TSLP had comitogenic activity for fetal thymocytes, but was not as potent as interleukin 7 in lobe submersion cultures. Injection of TSLP into neonatal mice induced the expansion of B220(+)BP-1(+) pre-B cells.

Inhibition of murine B and T lymphopoiesis in vivo by an anti-interleukin 7 monoclonal antibody.

The effects of interleukin 7 (IL-7) on the growth and differentiation of murine B cell progenitors has been well characterized using in vitro culture methods. We have investigated the role of IL-7 in vivo using a monoclonal antibody that neutralizes IL-7. We find that treatment of mice with this antibody completely inhibits the development of B cell progenitors from the pro-B cell stage forward. We also provide evidence that all peripheral B cells, including those of the B-1 and conventional lineages, are derived from IL-7-dependent precursors. The results are consistent with the rapid turnover of B cell progenitors in the marrow, but a slow turnover of mature B cells in the periphery. In addition to effects on B cell development, anti-IL-7 treatment substantially reduced thymus cellularity, affecting all major thymic subpopulations.

Recombinant interleukin 7, pre-B cell growth factor, has costimulatory activity on purified mature T cells.

The activation of highly purified murine peripheral T cells in vitro by Con A is dependent on a co-stimulatory signal that is not IL-1 or IL-2. Previous evidence has demonstrated that the recently defined lymphokine IL-6 could provide costimulatory activity for purified T cells cultured with Con A. In this report we demonstrate that IL-7 also has potent co-stimulatory activity for purified murine T cells, as well as its previously described ability to support the growth of pre-B cells in Witte-Whitlock cultures. When rIL-7 was added to cultures of purified T cells together with Con A, it induced the expression of IL-2 receptors, IL-2 production, and consequently proliferation. In addition, IL-7 exhibited the same magnitude of activity in this assay as IL-6. Also, anti-IL-6 antibody which inhibited the IL-6-induced response had no effect on the IL-7 response. Thus, IL-7 does not act by inducing IL-6. These results demonstrate that IL-7, a potent growth stimulus for pre-B cells, also has a role in T cell activation.

Cloning of the murine thymic stromal lymphopoietin (TSLP) receptor: Formation of a functional heteromeric complex requires interleukin 7 receptor.

The cellular receptor for murine thymic stromal lymphopoietin (TSLP) was detected in a variety of murine, but not human myelomonocytic cell lines by radioligand binding. cDNA clones encoding the receptor were isolated from a murine T helper cell cDNA library. TSLP receptor (TSLPR) is a member of the hematopoietin receptor family. Transfection of TSLPR cDNA resulted in only low affinity binding. Cotransfection of the interleukin 7 (IL-7)Ralpha chain cDNA resulted in conversion to high affinity binding. TSLP did not activate cells from IL-7Ralpha(-/)- mice, but did activate cells from gammac(-/)- mice. Thus, the functional TSLPR requires the IL-7Ralpha chain, but not the gammac chain for signaling.