Social disruption alters pain and cognition in an animal model of multiple sclerosis.

Although pain and cognitive deficits are widespread and debilitating symptoms of multiple sclerosis (MS), they remain poorly understood. Theiler's murine encephalomyelitis virus (TMEV) infection is an animal model of MS where disease course is exacerbated by prior stressors. Here chronic infection coupled with prior social stress increased pain behavior and impaired hippocampal-dependent memory consolidation during the demyelinating phase of disease in SJL mice. These results suggest that the TMEV model may be useful in investigating pain and cognitive impairments in MS. However, in contrast to prior Balb/cJ studies, stress failed to consistently alter behavioral and physiological indicators of disease course.

Neonatal experience interacts with adult social stress to alter acute and chronic Theiler's virus infection.

Previous research has shown that neonatal handling has prolonged protective effects associated with stress resilience and aging, yet little is known about its effect on stress-induced modulation of infectious disease. We have previously demonstrated that social disruption stress exacerbates the acute and chronic phases of the disease when applied prior to Theiler's virus infection (PRE-SDR) whereas it attenuates disease severity when applied concurrently with infection (CON-SDR). Here, we asked whether neonatal handling would protect adult mice from the detrimental effects of PRE-SDR and attenuate the protective effects of CON-SDR on Theiler's virus infection. As expected, handling alone decreased IL-6 and corticosterone levels, protected the non-stressed adult mice from motor impairment throughout infection and reduced antibodies to myelin components (PLP, MBP) during the autoimmune phase of disease. In contrast, neonatal handling X PRE/CON-SDR elevated IL-6 and reduced corticosterone as well as increased motor impairment during the acute phase of the infection. Neonatal handling X PRE/CON-SDR continued to exacerbate motor impairment during the chronic phase, whereas only neonatal handling X PRE-SDR increased in antibodies to PLP, MOG, MBP and TMEV. Together, these results imply that while handling reduced the severity of later Theiler's virus infection in non-stressed mice, brief handling may not be protective when paired with later social stress.

Social disruption induced priming of CNS inflammatory response to Theiler's virus is dependent upon stress induced IL-6 release.

Chronic social disruption stress (SDR) exacerbates acute and chronic phase Theiler's murine encephalomyelitis virus (TMEV) infection, a mouse model of multiple sclerosis. However, the precise mechanism by which this occurs remains unknown. The present study suggests that SDR exacerbates TMEV disease course by priming virus-induced neuroinflammation. It was demonstrated that IL-1ß mRNA expression increases following acute SDR; however, IL-6 mRNA expression, but not IL-1ß, is upregulated in response to chronic SDR. Furthermore, this study demonstrated SDR prior to infection increases infection related central IL-6 and IL-1ß mRNA expression, and administration of IL-6 neutralizing antibody during SDR reverses this increase in neuroinflammation.

Neonatal maternal separation alters immune, endocrine, and behavioral responses to acute Theiler's virus infection in adult mice.

Previous studies have established a link between adverse early life events and subsequent disease vulnerability. The present study assessed the long-term effects of neonatal maternal separation on the response to Theiler's murine encephalomyelitis virus infection, a model of multiple sclerosis. Balb/cJ mouse pups were separated from their dam for 180-min/day (180-min MS), 15-min/day (15-min MS), or left undisturbed from postnatal days 2-14. During adolescence, mice were infected with Theiler's virus and sacrificed at days 14, 21, or 35 post-infection. Prolonged 180-min MS increased viral load and delayed viral clearance in the spinal cords of males and females, whereas brief 15-min MS increased the rate of viral clearance in females. The 15-min and 180-min MS mice exhibited blunted corticosterone responses during infection, suggesting that reduced HPA sensitivity may have altered the immune response to infection. These findings demonstrate that early life events alter vulnerability to CNS infection later in life. Therefore, this model could be used to study gene-environment interactions that contribute to individual differences in susceptibility to infectious and autoimmune diseases of the CNS.

Restraint stress decreases virus-induced pro-inflammatory cytokine mRNA expression during acute Theiler's virus infection.

Stressful life events have been associated with the onset and/or exacerbation of multiple sclerosis (MS). Our previous studies have indicated that restraint stress (RS) reduces inflammation and virus-induced chemokine expression in the Theiler's virus-induced demyelination (TVID) model of MS. Here we report that RS significantly reduced the virus-induced interferon-gamma mRNA levels in the brain. Additionally, mRNA levels of lymphotoxin-beta, tumor necrosis factor-alpha, and interferon-gamma in the brain were negatively correlated with viral titers in the brain. These results indicated an immunosuppressive effect of stress during early TVID causing impaired viral clearance, which may be a potential exacerbating factor for later demyelination.

Alterations in chemokine expression following Theiler's virus infection and restraint stress.

Restraint stress (RS) applied to mice during acute infection with Theiler's virus causes corticosterone-induced immunosuppression. This effect was further investigated by measuring chemokine changes in the spleen and central nervous system (CNS) using an RNase Protection Assay. mRNAs for lymphotactin (Ltn), interferon-induced protein-10 (IP-10), MIP-1 beta, monocyte chemoattractant protein-1 (MCP-1) and TCA-3 were detected in the spleen at day 2 pi, but not in the brain of CBA mice infected with Theiler's virus. Ltn, IP-10 and RANTES were elevated in both the spleen and the brain at day 7 pi, and were significantly decreased by RS in the brain. RS also resulted in decreased inflammation within the CNS.

The effects of restraint stress on the neuropathogenesis of Theiler's virus infection II: NK cell function and cytokine levels in acute disease.

Psychological stress is thought to play an important role in multiple sclerosis. We have been investigating the role of restraint stress in Theiler's virus infection in mice as a model for multiple sclerosis. We have previously determined that restraint stressed CBA mice had higher levels of mortality following infection with Theiler's virus. We proposed that this was due to high levels of stress-induced corticosterone, which resulted in decreased numbers of circulating lymphocytes, decreased inflammatory cell infiltrates into the brain and consequently decreased viral clearance from the central nervous system (CNS). The effect of restraint stress on the innate immune response to Theiler's virus is further investigated in the current study. Restraint stressed mice developed clinical signs of encephalitis, thymic atrophy, and adrenal hypertrophy. Decreased numbers of circulating lymphocytes and increased numbers of neutrophils were observed in the stressed mice. Stressed mice also had lower numbers of spleen cells which correlated with the decreased numbers of lymphocytes in circulation. Restraint stress caused elevations in serum tumor necrosis alpha (TNF-alpha). Virus-induced natural killer cell (NK) cytotoxic activity was significantly reduced in restrained mice at one day post infection which may account for the reduced viral clearance from the CNS. These data suggest that stress-induced immunosuppression of cytolytic NK cell activity may account in part for the reduced ability to clear virus from the CNS and increased mortality observed in this model.

Social stress alters the severity of acute Theiler's virus infection.

Our laboratory has previously shown that restraint stress resulted in decreased Theiler's virus-induced CNS inflammation, while exacerbating illness behaviors during the acute phase of disease. In contrast, social disruption stress (SDR) applied prior to infection led to the development of glucocorticoid (GC) resistance, and these animals developed more severe disease course, with increased inflammation. However, when SDR was applied concurrent with infection, GC resistance fails to develop, disease course is less severe and inflammation was moderate. These results suggest that the effects of SDR on Theiler's virus infection are dependent upon the timing of SDR application in relation to infection.

Mitochondrial DNA and RAPD polymorphisms in the haploid mite Brevipalpus phoenicis (Acari: Tenuipalpidae).

Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) is recognized as the vector of citrus leprosis virus that is a significant problem in several South American countries. Citrus leprosis has been reported from Florida in the past but no longer occurs on citrus in North America. The disease was recently reported in Central America, suggesting that B. phoenicis constitutes a potential threat to the citrus industries of North America and the Caribbean. Besides B. phoenicis, B. obovatus Donnadieu, and B. californicus (Banks) have been incriminated as vectors of citrus leprosis virus and each species has hundreds of host plants. In this study, Brevipalpus mite specimens were collected from different plants, especially citrus, in the States of Florida (USA) and São Paulo (Brazil), and reared on citrus fruit under standard laboratory conditions. Mites were taken from these colonies for DNA extraction and for morphological species identification. One hundred and two Random Amplified Polymorphic DNA (RAPD) markers were scored along with amplification and sequencing of a mitochondrial cytochrome oxidase subunit I gene fragment (374 bp). Variability among the colonies was detected with consistent congruence between both molecular data sets. The mites from the Florida and Brazilian colonies were morphologically identified as belonging to B. phoenicis, and comprise a monophyletic group. These colonies could be further diagnosed and subdivided geographically by mitochondrial DNA analysis.

A general polyploid model for analyzing gene segregation in outcrossing tetraploid species.

Polyploidy has played an important role in higher plant evolution and applied plant breeding. Polyploids are commonly categorized as allopolyploids resulting from the increase of chromosome number through hybridization and subsequent chromosome doubling or autopolyploids due to chromosome doubling of the same genome. Allopolyploids undergo bivalent pairing at meiosis because only homologous chromosomes pair. For autopolyploids, however, all homologous chromosomes can pair at the same time so that multivalents and, therefore, double reductions are formed. In this article, we use a maximum-likelihood method to develop a general polyploid model for estimating gene segregation patterns from molecular markers in a full-sib family derived from an arbitrary polyploid combining meiotic behaviors of both bivalent and multivalent pairings. Two meiotic parameters, one describing the preference of homologous chromosome pairing (expressed as the preferential pairing factor) typical of allopolyploids and the other specifying the degree of double reduction of autopolyploids, are estimated. The type of molecular markers used can be fully informative vs. partially informative or dominant vs. codominant. Simulation studies show that our polyploid model is well suited to estimate the preferential pairing factor and the frequency of double reduction at meiosis, which should help to characterize gene segregation in the progeny of autopolyploids. The implications of this model for linkage mapping, population genetic studies, and polyploid classification are discussed.

The effects of restraint stress on the neuropathogenesis of Theiler's virus infection: I. Acute disease.

Restraint stress was found to have a profound effect on the acute phase of Theiler's virus infection. Increased mortality rates were observed in restrained CBA mice infected with the BeAn strain of Theiler's virus. In addition, restrained mice developed higher CNS viral titers than infected/nonrestrained mice. Thymic atrophy was observed in both infected and uninfected restrained mice. Decreased microgliosis, perivascular cuffing, and astrocytosis were observed in restrained mice compared to nonrestrained infected mice at 7 days postinfection. Restraint-stressed mice also developed decreased numbers of lymphocytes and increased numbers of neutrophils in the blood. The mechanism proposed for these alterations involves stress-induced corticosterone, which causes immunosuppression, decreased trafficking of inflammatory cells in the CNS, and, consequently, increased viral replication.

Shock-induced hyperalgesia: IV. Generality.

Brief-moderate shock (3, 0.75 s, 1.0 mA) has opposite effects on different measures of pain, inducing antinociception on the tail-flick test while lowering vocalization thresholds to shock and heat (hyperalgesia) and enhancing fear conditioned by a gridshock unconditioned stimulus (US). This study examined the generality of shock-induced hyperalgesia under a range of conditions and explored parallels to sensitized startle. Reduced vocalization thresholds to shock and antinociception emerged at a similar shock intensity. Severe shocks (3, 25 s, 1.0 mA or 3, 2 s, 3.0 mA) lowered vocalization threshold to shock but increased vocalization and motor thresholds to heat and undermined fear conditioned by a gridshock or a startling tone US. All shock schedules facilitated startle, but only brief-moderate shock inflated fear conditioning. The findings suggest that brief-moderate shock enhances the affective impact of aversive stimuli, whereas severe shocks attenuate pain.

Parental effects in the inheritance of nonnodulation in peanut.

A nonnodulating line (M4-2) and three normal nodulating lines (UF 487A, PI 262090, and Florunner) of peanut (Arachis hypogaea L.) were crossed in full diallel to investigate the inheritance of nodulation. Data from F1, F2, F3, F1BC1, and F2BC1 generations indicated that three genes control nodulation at three independent loci, with nodulation being a product of two genes and inhibited by a third gene when it is dominant and the others are homozygous recessive. A genetic model has been proposed that describes the nonnodulated genotypes as n1n1n2n2N3N3 or n1n1n2n2N3n3 and all other genotypes as normally nodulated except n1n1N2n2N3-, which has reduced nodulation when the n1n2N3 male gamete unites with the n1N2- female gamete or when the n1n2n3 male gamete unites with the n1N2N3 female gamete.

Structural studies in solution of the recombinant N-terminal pair of short consensus/complement repeat domains of complement receptor type 2 (CR2/CD21) and interactions with its ligand C3dg.

Human complement receptor type 2 (CR2, CD21) is a cell surface receptor that binds three distinct ligands (complement C3d, Epstein-Barr virus gp350/220, and the low-affinity IgE receptor CD23) via the N-terminal two of fifteen or sixteen short consensus/complement repeat (SCR) domains. Here, we report biophysical studies of the CR2 SCR 1-2 domain binding to its ligand C3dg. Two recombinant forms of CR2 containing the SCR 1-2 and SCR 1-15 domains were expressed in high yield in Pichia pastoris and baculovirus, respectively. Circular dichroism spectroscopy showed that CR2 SCR 1-2 receptor possessed a beta-sheet secondary structure with a melting temperature of 59 degrees C. Using surface plasmon resonance, kinetic parameters for the binding of either CR2 SCR 1-2 or the full-length SCR 1-15 form of CR2 showed that the affinity of binding to immobilized C3d is comparable for the SCR 1-15 compared to the SCR 1-2 form of CR2. Unexpectedly, both the association and dissociation rates for the SCR 1-15 form were slower than for the SCR 1-2 form. These data show that the SCR 1-2 domains account for the primary C3dg binding site of CR2 and that the additional SCR domains of full-length CR2 influence the ability of CR2 SCR 1-2 to interact with its ligand. Studies of the pH and ionic strength dependence of the interaction between SCR 1-2 and C3d by surface plasmon resonance showed that this is influenced by charged interactions, possibly involving the sole His residue in CR2 SCR 1-2. Sedimentation equilibrium studies of CR2 SCR 1-2 gave molecular weights of 17 000, in good agreement with its sequence-derived molecular weight to show that this was monomeric. Its sedimentation coefficient was determined to be 1.36 S. The complex with C3d gave molecular weights in 50 mM and 200 mM NaCl buffer that agreed closely with its sequence-derived molecular weight of 50 600 and showed that a 1:1 complex had been formed. Molecular graphics views of homology models for the separate CR2 SCR 1 and SCR 2 domains showed that both SCR domains exhibited a distribution of charged groups throughout its surface. The single His residue is located near a long eight-residue linker between the two SCR domains and may influence the linker conformation and the association of C3d and CR2 SCR 1-2 into their complex. Sedimentation modeling showed that the arrangement of the two SCR domains in CR2 SCR 1-2 is highly extended in solution.

Psychometric evaluation of the Beck Depression Inventory-II with primary care medical patients.

This study evaluated the psychometric characteristics of the Beck Depression Inventory-II (BDI-II; A. T. Beck, R. A. Steer, & G. K. Brown, 1996) in a primary care medical setting. A principal-components analysis with Promax rotation indicated the presence of 2 correlated factors, Somatic-Affective and Cognitive, which explained 53.5% of the variance. A hierarchical, second-order analysis indicated that all items tap into a second-order construct of depression. Evidence for convergent validity was provided by predicted relationships with subscales from the Short-Form General Health Survey (SF-20; A. L. Stewart, R. D. Hayes, & J. E. Ware, 1988). A receiver operating characteristic analysis demonstrated criterion-related validity: BDI-II scores predicted a diagnosis of major depressive disorder (MDD), as determined by the Primary Care Evaluation of Mental Disorders (PRIME-MD) Patient Health Questionnaire (PHQ). This study demonstrated that the BDI-II yields reliable, internally consistent, and valid scores in a primary care medical setting, suggesting that use of the BDI-II in this setting may improve detection and treatment of depression in these medical patients.

Requirement for the murine zinc finger protein ZFR in perigastrulation growth and survival.

The transition from preimplantation to postimplantation development leads to the initiation of complex cellular differentiation and morphogenetic movements, a dramatic decrease in cell cycle length, and a commensurate increase in the size of the embryo. Accompanying these changes is the need for the transfer of nutrients from the mother to the embryo and the elaboration of sophisticated genetic networks that monitor genomic integrity and the homeostatic control of cellular growth, differentiation, and programmed cell death. To determine the function of the murine zinc finger protein ZFR in these events, we generated mice carrying a null mutation in the gene encoding it. Homozygous mutant embryos form normal-appearing blastocysts that implant and initiate the process of gastrulation. Mutant embryos form mesoderm but they are delayed in their development and fail to form normal anterior embryonic structures. Loss of ZFR function leads to both an increase in programmed cell death and a decrease in mitotic index, especially in the region of the distal tip of the embryonic ectoderm. Mutant embryos also have an apparent reduction in apical vacuoles in the columnar visceral endoderm cells in the extraembryonic region. Together, these cellular phenotypes lead to a dramatic development delay and embryonic death by 8 to 9 days of gestation, which are independent of p53 function.

Pain and emotion: effects of affective picture modulation.

OBJECTIVE AND METHODS: Two experiments examined the impact of viewing unpleasant, pleasant, and neutral photographic slides on cold-pain perception in healthy men and women. In each experiment, participants viewed one of three slide shows (experiment 1 = fear, disgust, or neutral; experiment 2 = erotic, nurturant, or neutral) immediately before a cold-pressor task. Skin conductance and heart rate were recorded during the slide shows, whereas visual analog scale ratings of pain intensity and unpleasantness thresholds and pain tolerance were recorded during the cold-pressor task. RESULTS: Viewing fear and disgust slides decreased pain intensity and unpleasantness thresholds, but only the fear slides decreased pain tolerance. In contrast, viewing erotic, but not nurturant, slides increased pain intensity and unpleasantness threshold ratings on the visual analog scale in men, whereas neither nurturant nor erotic slides altered pain tolerance. CONCLUSIONS: These results are consistent with a motivational priming model that predicts that unpleasant affective states should enhance pain and that pleasant affective states should attenuate it.

Pain and negative affect: evidence the inverse benzodiazepine agonist DMCM inhibits pain and learning in rats.

RATIONALE: The anxiogenic DMCM, an inverse benzodiazepine agonist, was used to explore the relationship between negative affective states and pain. Past work suggests that the outcome obtained may depend on both the intensity of the affective state and the way in which pain is inferred. OBJECTIVES: The present study was designed to test the impact of relatively low doses of DMCM on multiple measures of pain reactivity and learning. METHODS: In experiment 1, systemic injections of 0.00, 0.015, 0.06, and 0.25 mg/kg DMCM were administered before vocalization and tail movements were assessed in response to a gradually incremented shock and radiant heat stimulus. Experiment 2 tested the effects of DMCM on Pavlovian conditioning. DMCM-treated subjects experienced a context paired with an aversive unconditioned stimulus (US) and conditioned freezing was assessed the next day. RESULTS: Experiment 1 showed that DMCM inhibits both a spinal nociceptive reflex (tail-flick to heat) and a supraspinal measure of pain (vocalization to shock). Because these inhibitory effects could reflect a disruption in motor function, experiment 2 employed a remote test based on Pavlovian conditioning. A moderate dose of DMCM undermined learning, implying that the drug decreased the affective impact of the aversive US. CONCLUSIONS: DMCM induces hypoalgesia on a wide range of assays. Furthermore, pharmacologically inducing a negative affective state blocks Pavlovian fear conditioning. It is suggested that DMCM induces a state of panic and that this state inhibits pain.

Linkage between loci controlling nodulation and testa variegation in peanut.

Linkage of loci controlling nodulation (N(1)) and testa variegation (V) was studied for cultivated peanut (Arachis hypogaea L.). The lines M4-2 (nonnodulating, variegated; VVn(1)n(1)n(2)n(2)N(3)N(3)) and UF 487A (nodulating, nonvariegated; vvN(1)N(1)n(2)n(2)N(3)N(3)) were used as parents in the crosses M4-2 x UF 487A, M4-2 x (UF 487A x M4-2), and their reciprocals. Individual plants were evaluated for nodulation and testa variegation in the F(1), F(2), F(3), F(1)BC(1), and F(2)BC(1) generations. Data indicate that the N(1) and V loci are linked with calculated crossover percentage of 7.1%.

Noise stress and human pain thresholds: divergent effects in men and women.

Considerable animal research suggests that exposure to noxious and nonnoxious fear-inducing stimuli can produce hypoalgesia. Although this effect is thought to generalize across species, only a few studies have examined the pain modulatory effects of nonnoxious fear-eliciting stimuli in humans. The present study examined whether exposure to a series of loud noise bursts would produce a fear-related hypoalgesia in male and female human subjects. Both subjective and physiologic measures (skin conductance level, heart rate) indicated that noise exposure resulted in fear, sympathetic arousal, and decreased pain reactivity in women (n = 20). In contrast, men (n = 20) did not experience fear or physiologic arousal, but reacted with surprise and increased pain reactivity. These findings provide additional evidence that hypoalgesia is mediated by fear and physiologic arousal. Although future studies should directly manipulate surprise, it appears that surprise without fear and physiologic arousal might enhance pain processing.