Naive Counterparts Research Articles

Stunting syndrome in broilers: Effect of electrolytes in drinking water on performance and intestinal glucose transport

1. Posthatched naive or inoculated male broiler chicks were kept in separate rooms. An inoculum was prepared from intestines of stunting-syndrome affected broiler chicks. 2. Tap water was supplied from 2 L cups, 1 cup per pen. In the Ist experiment, the naive chicks were provided with tap water only and the inoculated ones had free access to tap water or to an electrolyte solution. In the 2nd experiment, the naive and inoculated birds had free access to water in addition to an electrolyte solution. Supplementation was provided up to 3 weeks of age; thereafter all chicks had access to tap water only. Water or electrolyte consumption and body weight (BW) were determined. 3. Total water intake of inoculated chicks was higher than that of naive counterparts ( P <0 001). Electrolyte supplementation increased drinking ( P <0 001) in inoculated birds more than in naive ones. At 1 week old the weight of the inoculated birds was about 64% of the weight of naive ones; at the age of 4 and 6 weeks it was about 74% and 86% respectively . 4. Compensatory growth was most apparent in the inoculated chicks provided with electrolyte solution. At the age of 6 weeks, the latter exceeded the BW of the exclusively water supplied counterparts by 327 g. Electrolyte supplementation up to the age of 3 weeks had no effect on the naive counterparts. 5. Osmolality was reduced slightly, but very significantly by inoculation; electrolyte supply had no effect on this variable. Sodium concentration in the plasma was higher in the inoculated birds. Plasma albumin was markedly reduced by inoculation on weeks 1 and 2. Whereas the inoculated chicks supplied with electrolytes resumed the level plasma albumin level of the naive chicks on week 3, an over-compensation occurred in the inoculated-water-supplied (IW) group, and they surpassed the naive chicks significantly. Blood hematocrit increased significantly with age; inoculation, age and/or electrolyte supplementation had no effect on this variable. 6. Sodium-dependent glucose transport rates were enhanced in vesicles obtained from inoculated chicks as compared to naive ones. While electrolyte supplementation had no effect on glucose active transport in naive chicks, electrolyte supplementation decreased rates of glucose active transport in inoculated ones. 7. These data demonstrate that electrolyte supplementation during the early age may be used to enhance the tolerance of broiler chicks to stunting-syndrome by improving food and water consumption, and subsequently growth rate during and after cessation of electrolyte supply.

THE INFORMATION DILEMMA IN NEGOTIATIONS: EFFECTS OF EXPERIENCE, INCENTIVES, AND INTEGRATIVE POTENTIAL

This paper investigates the information dilemma in negotiations: if negotiators reveal information about their priorities and preferences, more efficient agreements may be reached but the shared information may be used strategically by the other negotiator, to the revealers' disadvantage. We present a theoretical model that focuses on the characteristics of the negotiators, the structure of the negotiation, and the available incentives; it predicts that experienced negotiators will out‐perform naive negotiators on distributive (competitive) tasks, especially when they have information about their counterpart's preferences and the incentives are high—unless the task is primarily integrative, in which case information will contribute to the negotiators maximizing joint gain. Two experiments (one small, one large) showed that the revelation of one's preferences was costly and that experienced negotialors outperformed their naive counterparts by a wide margin, particularly when the task and issues were distributive and incentives were large. Our results help to identify the underlying dynamics of the information dilemma and lead to a discussion of the connections between information and social dilemmas and the potential for avoiding inefficiencies.

Functional Characteristics and Survival Requirements of Memory CD4+ T Lymphocytes In Vivo

The phenotypic and functional characteristics of Ag-specific memory CD4+ lymphocytes are poorly defined. To examine the properties and cytokine responsiveness of these cells, we have developed an adoptive transfer system using in vitro-activated T cells expressing the DO.11 transgenic TCR specific for OVA(323-339)+ I-Ad. In vitro-activated DO.11 CD4+ cells exhibit comparable survival patterns at 1, 6, and 10 wk after adoptive transfer, indicating that a stable population of memory cells has been generated. In the absence of Ag, previously activated T cells survive longer than their naive counterparts in vivo, rapidly revert to a partially naive phenotype, and maintain their effector cytokine profile. The DO.11 CD4+ memory cells are capable of proliferating in response to IL-2 and IL-4, while naive DO.11 CD4+ cells exhibit no such proliferative responses.

Maturation of human neonatal CD4 + and CD8 + T lymphocytes into Th1/Th2 effectors

The increased susceptibility of neonates to infections has been ascribed to the immaturity of their immune system. More particularly, T cell-dependent responses were shown to be biased towards a Th2 phenotype. Our studies on the in vitro maturation of umbilical cord blood T cells suggest that the Th2 bias of neonatal response cannot be simply ascribed to intrinsic properties of neonatal T cells. Phenotypically, neonatal CD4 + T cells are more immature than their adult CD45RO −/RA + naive counterparts and they contain a subset (10–20%) of CD45RO −/RA + CD31 − cells which is very low in adults and displays some unique functional features. The activation and maturation of neonatal CD4 + T cells is particularly dependent upon the strength of CD28-mediated cosignal which dictates not only the cytokine profile released upon primary activation but also the response to IL-12. Activation of adult as well as neonatal CD4+ T cells in the context of low CD28 costimulation yields to the production of low levels of only one cytokine, i.e. IL-2. In contrast, strong CD28 costimulation supports the production of high levels of type 1 (IL-2, IFNγ and TNFβ) and low levels of type 2 (IL-4 and IL-13) cytokines by neonatal T cells. The low levels of naive T cell-derived IL-4 are sufficient to support their development into high IL-4/IL-5 producers by an autocrine pathway. The ability of IL-12 to prime neonatal CD4 + T cells for increased production of IL-4 (in addition to IFNγ) is observed only when CD28 cosignal is minimal. Under optimal activation conditions (i.e. with anti-CD3/B7.1 or allogenic dendritic cells) the response and the maturation of neonatal and adult naive T cells are similar. Thus the Th2 bias of neonatal immune response cannot be simply ascribed to obvious intrinsic T cell defect but rather to particular conditions of Ag presentation at priming. Unlike CD4 + T cells, neonatal CD8 + T cells strictly require exogenous IL-4 to develop into IL-4/IL-5 producers. Most importantly, anti-CD3/B7-activated neonatal CD8 T cells coexpress CD4 as well as CCR5 and CXCR4 and are susceptible to HIV-1 infection in vitro.

Flow-Microfluorometric Monitoring of Oligoclonal CD8+ T Cell Responses to an Immunodominant Moloney Leukemia Virus-Encoded Epitope In Vivo

The TCR repertoire of CD8+ T cells specific for Moloney murine leukemia virus (M-MuLV)-associated Ags has been investigated in vitro and in vivo. Analysis of a large panel of established CD8+ CTL clones specific for M-MuLV indicated an overwhelming bias for V beta4 in BALB/c mice and for V beta5.2 in C57BL/6 mice. These V beta biases were already detectable in mixed lymphocyte:tumor cell cultures established from virus-immune spleen cells. Furthermore, direct ex vivo analysis of PBL from BALB/c or C57BL/6 mice immunized with syngeneic M-MuLV-infected tumor cells revealed a dramatic increase in CD8+ cells expressing V beta4 or V beta5.2, respectively. M-MuLV-specific CD8+ cells with an activated (CD62L-) phenotype persisted in blood of immunized mice for at least 2 mo, and exhibited decreased TCR and CD8 levels compared with their naive counterparts. In C57BL/6 mice, most M-MuLV-specific CD8+ CTL clones and immune PBL coexpressed V alpha3.2 in association with V beta5.2. Moreover, these V beta5.2+ V alpha3.2+ cells were shown to recognize the recently described H-2Db-restricted epitope (CCLCLTVFL) encoded in the leader sequence of the M-MuLV gag polyprotein. Collectively, our data demonstrate a highly restricted TCR repertoire in the CD8+ T cell response to M-MuLV-associated Ags in vivo, and suggest the potential utility of flow-microfluorometric analysis of V beta and V alpha expression in the diagnosis and monitoring of viral infections.

Interleukin 10 secretion and impaired effector function of major histocompatibility complex class II-restricted T cells anergized in vivo.

Continuous antigenic stimulation in vivo can result in the generation of so-called "anergic" CD4(+) or CD8(+) T cells that fail to proliferate upon antigenic stimulation and fail to develop cytolytic effector functions. Here we show that class II major histocompatibility complex-restricted T cells specific for influenza hemagglutinin (HA) that become anergic in mice expressing HA under control of the immunoglobulin kappa promoter exhibit an impaired effector function in causing diabetes in vivo, as compared to their naive counterparts, when transferred into immunodeficient recipients expressing HA under the control of the insulin promoter. Furthermore, HA-specific T cells anergized in vivo contain higher levels of interleukin (IL)-4 messenger RNA (mRNA) than naive and recently activated T cells with the same specificity and more than a 100-fold higher levels of IL-10 mRNA. The higher expression of the IL-10 gene is also evident at the protein level. These findings raise the interesting possibility that T cells rendered anergic in vivo have in fact become regulatory T cells that may influence neighboring immune responses through the release of IL-10.

Changes in function of antigen-specific lymphocytes correlating with progression towards diabetes in a transgenic model.

Mice that express influenza hemagglutinin under control of the rat insulin promoter (INS-HA) as well as a class II major histocompatibility complex (MHC)-restricted HA-specific transgenic TCR (TCR-HA), develop early insulitis with huge infiltrates, but progress late and irregularly to diabetes. Initially, in these mice, INS-HA modulates the reactivity of antigen-specific lymphocytes, such that outside the pancreas they do not cause lethal shock like their naive counterparts in single transgenic TCR-HA mice, when stimulated with high doses of antigen. Inside the pancreas, the antigen-specific cells do not initially attack the islet cells, and produce some IFN-gamma as well as IL-10 and IL-4. Spontaneous progression to diabetes, which can be accelerated by cyclophosphamide injection, is accompanied by a 10-fold increase in IFN-gamma and a 3-fold decrease in IL-10 and IL-4 production by the locally residing antigen-specific T cells. Also, total islets from non-diabetic mice contain more TNF-alpha, compared with diabetic mice. This scenario is consistent with the view that beta cell destruction depends upon the increased production of certain pro-inflammatory cytokines by infiltrating T cells. Our inability to detect Fas expression on beta cells, but not on lymphoid cells, in diabetic and non-diabetic mice, puts some constraints on the role of Fas in beta cell destruction.

Distinct CD4+ T cell helper requirements in Theileria parva-immune and -naive bovine CTL precursors.

There is strong evidence that class I MHC-restricted parasite-specific CD8+ CTL protect cattle against the protozoan parasite Theileria parva. As part of an effort to develop a subunit vaccine for the induction of these responses, we have investigated the factors involved in the generation of T. parva-specific CTL in cattle. Purified populations of bovine immune and naive CD8+ T cells were cocultured with autologous T. parva-infected lymphoblasts (TpL) in the presence or absence of immune CD4+ T cells or cytokine preparations. Neither population developed CTL activity when cultured with TpL alone, whereas incorporation of immune CD4+ T cells in the cultures supported the generation of parasite-specific CTL from both immune and naive CD8+ precursors. The helper function of parasite-specific CD4+ T cells for immune, but not naive, CTL precursors could be replaced by CD4+ T cells responding to an unrelated Ag or by the addition of T cell growth factors or recombinant bovine IL-2. In experiments with two-chamber culture plates, in which cocultures of CD4+ and CD8+ T cells with TpL were separated by a semipermeable membrane, CTL activity was observed to develop only in immune precursor populations. Hence, although bovine T. parva-specific CD8+ memory T cells need no helper signals other than IL-2 for activation, their naive counterparts require close contact with responding parasite-specific CD4+ T cells. This may reflect essential receptor-ligand interactions, or alternatively, a requirement for more stringent microenvironmental cytokine conditions.

C-Ha-rasEJtransfection in vascular smooth muscle cells circumvents PKC requirement during mitogenic signaling

In view of the prominent role of protein kinase C (PKC) in the regulation of vascular smooth muscle cell (VSMC) growth and differentiation, the present studies were conducted to assess the impact of c-Ha-rasEJ transfection on PKC-dependent growth programming. PKC activity was elevated in the cytosolic and particulate compartments of c-Ha-rasEJ VSMC, relative to naive or pSV2neo vector controls. Constitutive and 12-O-tetradecanoyl phorbol 13-acetate (TPA)-inducible binding to a TPA-responsive element (TRE) was also enhanced in c-Ha-rasEJ VSMC. Fetal bovine serum (FBS) did not increase TRE-binding activity in serum-starved c-Ha-rasEJ VSMC but increased TRE-binding activity in pSV2neo VSMC. FBS-mediated TRE-binding activity was dramatically decreased in serum-starved pSV2neo VSMC pretreated with 100 ng/ml TPA for 24 h to downregulate PKC activity. c-Ha-rasEJ VSMC exhibited a marked proliferative advantage over controls under both restrictive and growth-permissive serum conditions. PKC downregulation did not influence the mitogenic response to serum in c-Ha-rasEJ VSMC but ablated [3H]thymidine incorporation into DNA in naive or pSV2neo vector counterparts. Western blot analysis demonstrated increased expression of extracellular signal-regulated kinase 2 (ERK2), but not ERK1, in c-Ha-rasEJ VSMC, relative to pSV2neo control. Immunoblots of serum-starved and PKC-depleted c-Ha-rasEJ VSMC demonstrated a dramatic increase in the phosphorylated form of ERK2, relative to pSV2neo controls. These data suggest that oncogenic c-Ha-rasEJ circumvents a requirement for a TPA-responsive PKC isoform(s) during mitogenic stimulation of VSMC.

Stunting syndrome in broilers: effect of glucose or maltose supplementation on digestive organs, intestinal disaccharidases, and some blood metabolites

The effect of supplementing a cornsoybean diet (C) with glucose (G) or maltose (M) on young broilers (from hatch to 3 wk of age) affected by stunting syndrome (SS) was studied. Stunting syndrome was induced by orally administering an inoculum prepared from the intestines of SS broiler chicks. Relative to the M diet, the G diet improved growth and feed utilization and increased feed intake in naive (NA) control chickens. The C diet was intermediate in this respect. In contrast to the NA chickens, diet did not affect growth or feed utilization in SS chicks. Changes in the relative weights of the gastrointestinal tract segments were evident by 1 wk of age and hypertrophy of these segments persevered to 3 wk of age. Stunting syndrome infection was accompanied by a significant increase in pancreatic trypsin-specific activity during Weeks 1 and 2, and in chymotrypsin activity at 1 wk. During this time, amylase-specific activity was not affected. At 3 wk of age, the specific activities of amylase, trypsin, and chymotrypsin in the pancreas were lower in the inoculated vs control birds. Whereas no significant effect of SS was observed with activities of amylase in the intestinal contents, trypsin activity was higher in SS chicks at 1 wk, and that of chymotrypsin lower during Weeks 2 and 3. Relative to NA chicks, the maltase and saccharase activities of SS chicks were much lower during Week 1, but increased later on and were similar to NA chick values at 2 and 3 wk. Whereas the level of blood plasma proteins did not vary from 1 to 3 wk in the NA chicks, it increased gradually in SS chicks to a level that significantly exceeded that in their NA counterparts. Blood plasma glucose and triglyceride levels were slightly lower in the SS chicks (NS), and the blood plasma cholesterol level was significantly reduced during Week 2. Relative to NA chicks, SS infection caused a significant increase in plasma calcium during Weeks 2 and 3, accompanied by a significant reduction in blood plasma phosphorus at 2 wk only. No difference was observed in the blood plasma level of uric acid, which peaked in both treatments during Week 2, or in D-beta-hydroxybutyric acid level, which was quite stable during the experimental period. Stunting syndrome infection was accompanied by a dramatic increase in amylase and alkaline phosphatase activities in the blood plasma, and by a slight but significant decrease in activity of lactic dehydrogenase. Stunting syndrome was concluded to be an affliction not only of digestion but also of metabolism. The main depression in growth caused by SS inoculation is probably due to metabolic alterations beyond those of digestion and absorption.

Visualization, characterization, and turnover of CD8+ memory T cells in virus-infected hosts.

The cellular basis of T cell memory is a controversial issue and progress has been hampered by the inability to induce and to trace long-term memory T cells specific for a defined antigen in vivo. By using the murine model of lymphocytic choriomeningitis virus (LCMV) infection and an adoptive transfer system with CD8+ T cells from transgenic mice expressing an LCMV-specific T cell receptor, a population of authentic memory T cells specific for LCMV was generated and analyzed in vivo. The transgenic T cells that have expanded (1,000-fold) and then decreased (10-fold) in LCMV-infected C57BL/6 recipient mice exhibited the following characteristics: they were (a) of larger average cell size than their naive counterparts but smaller than day 8 effector cells; (b) heterogeneous with respect to expression of cell surface "memory" markers; and (c) directly cytolytic when isolated from recipient spleens. The time-dependent proliferative activity of these LCMV-specific memory T cells was analyzed in the recipients by bromodeoxyuridine labeling experiments in vivo. The experiments revealed that LCMV-specific CD8+ memory T cells can persist in LCMV-immune mice for extended periods of time (>2 mo) in the absence of cell division; the memory population as a whole survived beyond 11 mo.

Best replies and adaptive learning

This paper discusses the relationships between learning processes based on the iterated elimination of strictly dominated strategies and their myopic and more naive counterparts. The concept of a monotone game, of which games with strategic complementarities are a subclass, is introduced. Then it is shown that convergence under best reply dynamics and dominance solvability are equivalent for all two-player (and some many-player) games in this class.

Predation and Habitat Shift in the House Mouse, Mus Domesticus

This study investigates the responses of house mice (Mus domesticus) to two species of introduced mammalian predators in Western Australia, the red fox (Vulpes vulpes) and cat (Felis catus), and to an endemic carnivorous marsupial, the western quoll (Dasyurus geoffroii). In four study areas containing no mammalian predators, mice showed little discrimination between traps bearing fecal odors of the predators and traps bearing conspecific odors or no odor. Mice in these areas also used sites of different vegetation density roughly in proportion to their abundance, irrespective of the intensity of lunar illumination or whether densities of predator feces were high or low. These results suggest that predator—naive mice do not respond to predator odors or to different levels of predation risk. In contrast, mice in 12 other study areas containing one to three species of mammalian predators avoided traps with predator adors, and generally selected relatively dense vegetation. They also used sites of greater vegetation density on moonlit compared to dark nights, and in two study areas where the density of cat feces had been experimentally increased. These results indicate that mice in areas exposed to mammalian predators distinguish predator odors and use denser vegetation when the preceived risk of predation is increased. In further experiments, I introduced predator—naive and predator—experienced mice to study areas containing cats and foxes. Survival rates of experienced mice a month after release were 2½ times higher than those of their naive counterparts, and hence support the hypothesis that a habitat shift to dense vegetation is an effective anti—predator response.

Hypothesis Testing of Regression Parameters in Semiparametric Generalized Linear Models for Cluster Correlated Data

SUMMARY Generalized and 'working' Wald and score tests for regression coefficients in the class of semiparametric marginal generalized linear models for cluster correlated data (Liang & Zeger, 1986) are proposed, and their asymptotic distribution examined. In addition, the asymptotic distribution of the naive likelihood ratio test, or deviance difference, is presented. Following Rao & Scott (1984), we propose simple adjustments to such 'working' tests. The asymptotic distributions of the 'working' tests allow us to explore theoretical bounds on the ratios of the robust variance of the regression parameter estimators and their naive variance counterparts computed assuming independent observations. In addition, the adequacy of a particular choice of working correlation structure is considered. We illustrate our results with a numerical example.

Hypothesis testing of regression parameters in semiparametric generalized linear models for cluster correlated data

Generalized and ‘working’ Wald and score tests for regression coefficients in the class of semiparametric marginal generalized linear models for cluster correlated data (Liang & Zeger, 1986) are proposed, and their asymptotic distribution examined. In addition, the asymptotic distribution of the naive likelihood ratio test, or deviance difference, is presented. Following Rao & Scott (1984), we propose simple adjustments to such ‘working’ tests. The asymptotic distributions of the ‘working’ tests allow us to explore theoretical bounds on the ratios of the robust variance of the regression parameter estimators and their naive variance counterparts computed assuming independent observations. In addition, the adequacy of a particular choice of working correlation structure is considered. We illustrate our results with a numerical example.

Making up Our Minds: Effects of Network Coverage on Viewer Impressions of Leaders

This article asks the question, Can television journalism change public opinion? Through a controlled experiment in which 100 viewers were shown a presidential debate and its coverage by network news reporters, the authors explore viewer perceptions of the candidates, emotional reactions to them, and their recall of issues. They conclude that viewer opinions were influenced significantly by both the instant analysis and evening news reports, though politically more sophisticated viewers proved to be less affected by them than were their more naive counterparts.