Oligodendrocyte gene expression is reduced by and influences effects of chronic social stress in mice.

Oligodendrocyte gene expression is downregulated in stress-related neuropsychiatric disorders, including depression. In mice, chronic social stress (CSS) leads to depression-relevant changes in brain and emotional behavior, and the present study shows the involvement of oligodendrocytes in this model. In C57BL/6 (BL/6) mice, RNA-sequencing (RNA-Seq) was conducted with prefrontal cortex, amygdala and hippocampus from CSS and controls; a gene enrichment database for neurons, astrocytes and oligodendrocytes was used to identify cell origin of deregulated genes, and cell deconvolution was applied. To assess the potential causal contribution of reduced oligodendrocyte gene expression to CSS effects, mice heterozygous for the oligodendrocyte gene cyclic nucleotide phosphodiesterase (Cnp1) on a BL/6 background were studied; a 2 genotype (wildtype, Cnp1+/- ) × 2 environment (control, CSS) design was used to investigate effects on emotional behavior and amygdala microglia. In BL/6 mice, in prefrontal cortex and amygdala tissue comprising gray and white matter, CSS downregulated expression of multiple oligodendroycte genes encoding myelin and myelin-axon-integrity proteins, and cell deconvolution identified a lower proportion of oligodendrocytes in amygdala. Quantification of oligodendrocyte proteins in amygdala gray matter did not yield evidence for reduced translation, suggesting that CSS impacts primarily on white matter oligodendrocytes or the myelin transcriptome. In Cnp1 mice, social interaction was reduced by CSS in Cnp1+/- mice specifically; using ionized calcium-binding adaptor molecule 1 (IBA1) expression, microglia activity was increased additively by Cnp1+/- and CSS in amygdala gray and white matter. This study provides back-translational evidence that oligodendrocyte changes are relevant to the pathophysiology and potentially the treatment of stress-related neuropsychiatric disorders.

Altered emotionality and neuronal excitability in mice lacking KCTD12, an auxiliary subunit of GABAB receptors associated with mood disorders.

Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the brain, is fundamental to brain function and implicated in the pathophysiology of several neuropsychiatric disorders. GABA activates G-protein-coupled GABAB receptors comprising principal GABAB1 and GABAB2 subunits as well as auxiliary KCTD8, 12, 12b and 16 subunits. The KCTD12 gene has been associated with bipolar disorder, major depressive disorder and schizophrenia. Here we compare Kctd12 null mutant (Kctd12(-/-)) and heterozygous (Kctd12(+/-)) with wild-type (WT) littermate mice to determine whether lack of or reduced KCTD12 expression leads to phenotypes that, extrapolating to human, could constitute endophenotypes for neuropsychiatric disorders with which KCTD12 is associated. Kctd12(-/-) mice exhibited increased fear learning but not increased memory of a discrete auditory-conditioned stimulus. Kctd12(+/-) mice showed increased activity during the inactive (light) phase of the circadian cycle relative to WT and Kctd12(-/-) mice. Electrophysiological recordings from hippocampal slices, a region of high Kctd12 expression, revealed an increased intrinsic excitability of pyramidal neurons in Kctd12(-/-) and Kctd12(+/-) mice. This is the first direct evidence for involvement of KCTD12 in determining phenotypes of emotionality, behavioral activity and neuronal excitability. This study provides empirical support for the polymorphism and expression evidence that KCTD12 confers risk for and is associated with neuropsychiatric disorders.

Resuscitation of infants born at 22 weeks gestation: a 20-year retrospective.

OBJECTIVE: To compare the characteristics of infants born at 22 weeks gestational age (GA) who were resuscitated at birth with those of infants who were not resuscitated. STUDY DESIGN: We reviewed records of all the infants with a GA of 22 0/7 through 22 6/7 weeks who were born alive at William Beaumont Hospital from 1990 through 2009. Deliveries were attended by a neonatologist if they were in the hospital at the time of delivery or requested by the obstetrician and otherwise were attended by a pediatric resident or neonatal nurse practitioner. RESULT: There were 85 infants born alive at 22 weeks GA during the study period. Thirty-six were intubated in the delivery room and defined as having been resuscitated. Two of them survived. On multivariate analysis, a higher birth weight (odds ratio 2.39 per 100 g increase, 95% confidence interval 1.21 to 4.73) and the presence of a neonatologist at delivery (odds ratio 6.72, 95% confidence interval 1.72 to 26.2) were each associated with an increased likelihood of resuscitation. CONCLUSION: Infants born at 22 weeks GA were more likely to be resuscitated if they were larger or if the delivery was attended by a neonatologist. We encourage neonatal groups to follow the recommendations of the American Academy of Pediatrics Committee on the Fetus and Newborn regarding initiation of resuscitation in these infants: inform parents that a good outcome is very unlikely and respect the parents' choice of whether resuscitation should be initiated.

Safety of antiretroviral drug therapy in Jamaican children with HIV/AIDS / Seguridad de la terapia con medicamento antiretroviral en niños jamaicanos con VIH/SIDA

BACKGROUND: HIV has been a leading cause of death in Jamaican children aged # five years. Antiretroviral drugs (ARVs) are increasingly available in Jamaica through the Global Fund. Adverse effects of ARVs are a major cause for non-adherence to medications. Knowledge of the use and side effects of these drugs are crucial in the management of HIV-infected children as we scale-up the use of antiretroviral therapy, islandwide. We evaluated the adverse events and safety of antiretroviral therapy in children attending four Infectious Disease Clinics in Kingston, Jamaica, a resource limited setting. METHODS: Data for children prospectively enrolled in the Kingston Paediatric and Perinatal HIV/AIDS Programme during September 2002 to April 2005 were analyzed. RESULTS: Among 121 HIV-infected children, 77 (64%) were on ARVs, 90% had CDC class C disease, 60% were males and perinatal transmission predominated. AZT/3TC based regime was utilized in 93%, trimethoprim/sulphamethoxazole prophylaxis was used in 100% and five were completing anti-tuberculous drugs. Anaemia occurred in all patients, with increased severity in those on ARVs. Macrocytosis occurred in 83% and thrombocytopenia in 8% of those on ARVs. Elevation of bilirubin, aspartate transaminase (AST) and alanine transaminase (ALT) levels and reversed albumin to globulin ratio prior to commencing ARVs, with significantly lower prevalence following use of ARVs emphasized the severity of HIV disease at time of ARV initiation. Clinical adverse reactions were uncommon and included nail discoloration (8%), vomiting (7%), nausea (3%), peripheral lipodystrophy (4%) and abnormal dreams (1%). Ten children required change of ARV medication because of severe adverse effects: three for severe anaemia with repeat blood transfusions, three for severe nevirapine-associated rash and four for indinavir-associated haematuria. CONCLUSIONS: ARVs are being successfully initiated in HIV-infected Jamaican children using the public health model. The excellent safety profile, good tolerance and few reported significant adverse effects augur well as antiretroviral therapy is scaled-up islandwide.

ANTECEDENTES: EL VIH ha sido la principal causa de muerte en los niños jamaicanos de # cinco años de edad. Las drogas antiretrovirales (ARVs) se hallan cada vez más a disposición en Jamaica a través del Fondo Global. Los efectos adversos de los ARVs constituyen una causa fundamental para la no adherencia a los medicamentos. El conocimiento del uso y los efectos colaterales de estos medicamentos son cruciales para el tratamiento de los niños infectados por VIH en la medida en que escalamos el uso de la terapia antiretroviral a lo largo de toda la isla. Evaluamos los eventos adversos y la seguridad de la terapia antiretroviral en niños que asisten a cuatro clínicas de enfermedades infecciosas en Kingston, Jamaica, las cuales constituyen un escenario limitado en recursos. MÉTODOS: Se analizaron los datos de niños prospectivamente alistados en el Programa VIH/SIDA Prenatal y Pediátrico de Kingston, Jamaica, durante septiembre de 2002 hasta abril de 2005. RESULTADOS: Entre los 121 niños infectados con VIH, 77 (64%) estaban bajo medicación con ARVs, 90% tenían enfermedades del subgrupo C según la clasificación de CDC, 60% eran varones y predominó la transmisión perinatal. El régimen basado en AZT/3TC fue utilizado en 93%, trimeto-prima/sulfametoxazol se usó en el 100%, y cinco estaban completando medicamentos antituberculosos. La anemia estaba presente en todos los pacientes, con mayor severidad en aquellos bajo ARVs. Se observó macrocitosis en el 83% y trombocitopenia en un 8% de los que se hallaban bajo ARVs. La elevación de los niveles de bilirrubina, aspartato transaminasa (AST) y alanina transaminasa (ALT) y la relación albúmina/globulina invertida antes de comenzar con los ARVs, con una prevalencia significativamente menor tras el uso de los ARVs, enfatizaron la severidad de la enfermedad del VIH al momento de la iniciación del ARV. Las reacciones clínicas adversas fueron poco común e incluyeron decoloración de las uñas (8%), vómitos (7%), náuseas (3%), lipodistrofia periférica (4%) y sueños anormales (1%). Diez de los niños necesitaron cambio de medicación ARV debido a los severos efectos adversos: tres a causa de una anemia severa con repetidas transfusiones de sangre, tres debido a una severa erupción asociada con la nevirapina, y cuatro a causa de hematuria asociada con indinavir. CONCLUSIONES: Los medicamentos ARVs han comenzado a ser administrados exitosamente en niños jamaicanos infectados por el VIH, usando el modelo de salud pública. El excelente perfil de seguridad, la buena tolerancia y el pequeño número de efectos adversos significativos reportados, auguran un buen futuro a la escalada de la terapia antiretroviral en toda la isla.

Safety of antiretroviral drug therapy in Jamaican children with HIV/AIDS.

BACKGROUND: HIV has been a leading cause of death in Jamaican children aged < or = five years. Antiretroviral drugs (ARVs) are increasingly available in Jamaica through the Global Fund. Adverse effects of ARVs are a major cause for non-adherence to medications. Knowledge of the use and side effects of these drugs are crucial in the management of HIV-infected children as we scale-up the use of antiretroviral therapy, islandwide. We evaluated the adverse events and safety of antiretroviral therapy in children attending four Infectious Disease Clinics in Kingston, Jamaica, a resource limited setting. METHODS: Data for children prospectively enrolled in the Kingston Paediatric and Perinatal HIV/AIDS Programme during September 2002 to April 2005 were analyzed. RESULTS: Among 121 HIV-infected children, 77 (64%) were on ARVs, 90% had CDC class C disease, 60% were males and perinatal transmission predominated. AZT/3TC based regimen was utilized in 93%, trimethoprim/sulphamethoxazole prophylaxis was used in 100% and five were completing antituberculous drugs. Anaemia occurred in all patients, with increased severity in those on ARVs. Macrocytosis occurred in 83% and thrombocytopenia in 8% of those on ARVs. Elevation of bilirubin, aspartate transaminase (AST) and alanine transaminase (ALT) levels and reversed albumin to globulin ratio prior to commencing AR Vs, with significantly lower prevalence following use of ARVs emphasized the severity of HIV disease at time of ARV initiation. Clinical adverse reactions were uncommon and included nail discoloration (8%), vomiting (7%), nausea (3%), peripheral lipodystrophy (4%) and abnormal dreams (1%). Ten children required change of ARV medication because of severe adverse effects: three for severe anaemia with repeat blood transfusions, three for severe nevirapine-associated rash and four for indinavir-associated haematuria. CONCLUSIONS: ARVs are being successfully initiated in HIV-infected Jamaican children using the public health model. The excellent safety profile, good tolerance and few reported significant adverse effects augur well as antiretroviral therapy is scaled-up islandwide.

The impaired coping induced by early deprivation is reversed by chronic fluoxetine treatment in adult fischer rats.

The symptoms of depression include feelings of reduced coping ability and increased helplessness. Early life adversity increases vulnerability to depression. In rats, the quantification of ability to cope with adverse challenge can be achieved using preexposure to an inescapable aversive stimulus and subsequent assessment of escape or avoidance deficits in the same environment. Here we investigated the predictive validity of a model in which, in the Fischer rat strain, postnatal isolation leads in adulthood to a state of increased sensitivity to develop an escape or avoidance deficit. On days 1-14 rat pups were isolated for 4 hours (early deprivation, ED) or for 15 minutes (early handling, EH), or were left completely undisturbed (non-handling, NH). In adulthood, subjects were placed in a shuttle box and half were exposed to brief, mild foot shocks (preexposure, PE) and the other half were non-preexposed (NPE). Half of the PE and NPE subjects were then treated for 21 days with fluoxetine and the other half with vehicle. In males, although there was no overall preexposure effect on avoidance behaviour, ED-PE and ED-NPE and EH-PE and EH-NPE demonstrated an avoidance deficit relative to NH. Fluoxetine attenuated this deficit and most notably in ED-PE. In females, vehicle ED-PE demonstrated an avoidance deficit relative to NH-PE; fluoxetine attenuated this ED effect. These findings provide supportive evidence for the predictive validity of this depression model.

Amphetamine withdrawal does not produce a depressive-like state in rats as measured by three behavioral tests.

Administration of amphetamine (AMPH) can induce symptoms of psychosis in humans and locomotor sensitization in rats; in contrast, withdrawal from a period of AMPH intake is most often associated with symptoms of human endogenous depression. The aim of this study was to determine whether AMPH withdrawal produces a depressive-like state in rats. The present study examined the effects of withdrawal from an escalating-dose AMPH schedule (ESC; three daily injections over 6 days, 1-5 mg/kg, i.p.) and an intermittent-dose AMPH schedule (INT; one daily injection over 6 days, 1.5 mg/kg, i.p.) on animals' performance in three behavioral paradigms related to depression: the Porsolt swim test, the learned helplessness assay and operant responding for sucrose on a progressive ratio schedule. ESC and INT AMPH withdrawal had no effect on any of these tests or on stress responsiveness as measured by increased plasma levels of corticosterone (CORT) and adrenocorticotropin following the swim test, although basal CORT levels were higher in AMPH-withdrawn animals compared to controls. Finally, we confirmed the presence of locomotor sensitization for both AMPH schedules after 30 days of withdrawal. Our results suggest that the ability of AMPH withdrawal to produce symptoms of depression may not be evident in all behavioral screens for depressive symptoms in the rat.

Peripartum sex steroid profiles and endocrine correlates of postpartum maternal behavior in captive gorillas (Gorilla gorilla gorilla).

An association between pregnancy levels of estrogen and progesterone and maternal behavior has been demonstrated in several taxonomic orders of nonprimate and primate mammals, but has not so far been investigated in the gorilla. In this study we investigated whether prepartum titers of urinary estrone conjugates (E1C) or pregnanediol-3alpha-glucuronide (PdG) were related to postpartum maternal behavior in eight multiparous Western lowland gorilla females (Gorilla gorilla gorilla) housed in four zoological gardens. Urine samples were collected from each study animal for 14 days prepartum and 14 days postpartum, and measures of maternal responsiveness were scored during the first 15 days postpartum. Urine samples were assayed with radioimmunoassay for E1C and PdG. Results for the peripartum profiles of urinary E1C, as well as postpartum profiles of PdG, agree with previous findings for the gorilla, while results for late-pregnancy profiles of urinary PdG were inconclusive in confirming a prepartum increase or decrease. Neither prepartum levels of E1C or PdG, nor the E1C/PdG ratio were found to be related to measures of postpartum maternal behavior. This lack of association between late-pregnancy E1C titers per se and postpartum maternal behavior is contrary to findings in nonprimate and other primate species.

An automated analysis of rat behavior in the forced swim test.

The Porsolt forced swim test (FST) is a commonly used paradigm to evaluate antidepressant activity of drugs. This test is based on visual measurement of the rat's floating time (FT) in a tank filled with water. Here, we present an automated, accurate and faster method for estimating FT by the distance moved (DM) by the animal via the use of the Ethovision software in three separate experiments. Experiment 1 investigated the effect of varying delays (24-h and 7-day) between pretest and test on FT and DM. Experiment 2 aimed at examining the effects of a 2-day withdrawal period in rats sensitized to amphetamine and cocaine, on FT and DM. Finally, Experiment 3 looked at the effects of desipramine and fluoxetine on FT and DM. The results of these experiments show that increasing the delay between pretest and test reduced FT during subsequent exposure (test). In addition, rats sensitized to and then withdrawn from either amphetamine or cocaine did not differ in FT or DM compared with control rats. Finally, both desipramine and fluoxetine reduced FT and increased DM. Furthermore, DM was consistently significantly negatively correlated with FT. These results support the use of an automated method for the evaluation of rat behavior in FST.

Comparison of the effects of early handling and early deprivation on maternal care in the rat.

It has been reported in the rat that postnatal manipulations can induce robust and persistent effects on offspring neurobiology and behavior, mediated in part via effects on maternal care. There have, however, been few studies of the effects of postnatal manipulations on maternal care. Here, we describe and compare the effects on maternal behavior on postnatal days 1-12 of two manipulations, early handling (EH, 15-min isolation per day) and early deprivation (ED, 4-hr isolation per day), relative to our normal postnatal husbandry procedure. Maternal behavior was measured at five time points across the dark phase of the reversed L:D cycle. EH yielded an increase in arched-back nursing across several time points but did not affect any other behavior. ED stimulated a bout of maternal behavior such that licking and arched-back nursing were increased at the time of dam-litter reunion, although not at any other time point. Neither EH nor ED affected weaning weight significantly. Importantly, within-treatment variation was high relative to these between-treatment effects.

Comparison of the effects of infant handling, isolation, and nonhandling on acoustic startle, prepulse inhibition, locomotion, and HPA activity in the adult rat.

This study examined whether early isolation (EI), early handling (EH), or early nonhandling (NH) in infant rats alters (a) prepulse inhibition (PPI) of the acoustic startle response (ASR) or its disruption by apomorphine, (b) motor activity or its stimulation by amphetamine, or (c) corticosterone activity (because of its modulation of dopamine activity), in adulthood and in comparison with a normal-husbandry postnatal control environment. EI did not affect PPI, reduced PPI disruption by apomorphine in males, and increased amphetamine-stimulated activity in males. NH increased the ASR, reduced activity in the open field, and increased corticosterone reactivity in males. In all paradigms, the effects of EH were similar to those of the control environment. This study provides an important contribution to the evidence on the relationship between postnatal experience and long-term neurobehavioral development in the rat and the relevance of this approach to animal models of neuropsychiatric disorder.

Behavioral, neurochemical and endocrinological characterization of the early social isolation syndrome.

Rearing rats in isolation has been shown to be a relevant paradigm for studying early life stress and understanding the genesis of depression and related affective disorders. Recent studies from our laboratory point to the relevance of studying the social isolation syndrome as a function of home caging conditions. Accordingly, the present series of experiments assessed the contribution of each condition to the expression of the prepulse inhibition of the acoustic startle, food hoarding and spontaneous locomotor activity. In addition, ex vivo neurochemical changes in the brains of isolated and grouped rats reared either in sawdust-lined or in grid-floor cages were determined by measuring dopamine and serotonin as well as their major metabolites in a "psychosis circuit" that includes mainly the hippocampus and selected hippocampal efferent pathways projecting towards the anterior cingulate and infralimbic cortices, nucleus accumbens, dorsolateral caudate nucleus, amygdala and entorhinal cortex. The results of the present study demonstrate that rearing rats in isolation (i) produces a syndrome of generalized locomotor hyperactivity; (ii) increases the startle response; (iii) impairs prepulse inhibition; (iv) tends to increase food hoarding behavior; (v) increases basal dopamine turnover in the amygdaloid complex; (vi) decreases basal dopamine turnover in the infralimbic part of the medial prefrontal cortex; and (vii) decreases basal turnover of serotonin in the nucleus accumbens. In the entorhinal cortex, dopamine neurotransmission seemed to be more sensitive to the caging conditions since a decreased basal turnover of dopamine was observed in grid-reared animals. Plasma corticosterone levels were also increased in grid-reared animals compared with rats reared in sawdust cages. Finally, isolates reared on grids showed a significant positive correlation between plasma corticosterone levels and dopamine in the left nucleus accumbens.Altogether, these results support the contention that there is a link between social isolation, attention deficit, spontaneous locomotor hyperactivity and reduced dopamine turnover in the medial prefrontal cortex. Furthermore, our data demonstrate that rearing rats in grid-floor cages represents a form of chronic mild stress associated with increased corticosterone levels, decreased basal turnover of entorhinal dopamine and increased dopamine activity in the left nucleus accumbens. Finally, a significant and selective decrease in the basal turnover of serotonin in the nucleus accumbens of isolated rats may be linked to the isolation-induced locomotor hyperactivity.

Lack of effect of an early stressful life event on sensorimotor gating in adult rats.

Hypotheses of the etiology of schizophrenia emphasize the important role of perinatal insults in predisposing individuals to the development of the disease, so that an animal model in which a discrete postnatal manipulation of the infant social environment yields schizophrenia-like behavior in adulthood would be valuable in terms of the study of the neural substrate and treatment of schizophrenia. Schizophrenics demonstrate a deficit in sensorimotor gating (prepulse inhibition), and a similar phenomenon has been described in adult rats following the administration of direct and indirect dopamine agonists. Recently it has been reported that a 24 h separation of rat pups from the mother results in a disruption of prepulse inhibition at adulthood. Here we report a study which investigated the same phenomenon but which, in contrast to the previous study, utilized unrelated subjects all derived from different dams. Maternal separation was conducted for 24 h with pups aged 4, 9 or 18 days and these subjects, together with non-separated controls, were tested at age 3 months in terms of their prepulse inhibition in the acoustic startle response paradigm. Maternal separation did not disrupt prepulse inhibition. Comparison of males and females (with a maximum of one opposite-sex sibling) demonstrated that acoustic startle response and prepulse inhibition of this response was enhanced in males relative to females. This study indicates that 24 h maternal separation does not provide a robust model for studying the effects of early environmental insults on the long-term abnormal development of sensorimotor gating.

Lewis/Fischer rat strain differences in endocrine and behavioural responses to environmental challenge.

The Lewis (LEW) and Fischer (F344) rat strains provide a comparative model of hypothalamic-pituitary-adrenal (HPA) function in which LEW is relatively hypoactive at homeostasis and hyporeactive to environmental challenge. The present study describes a comparison of LEW and F344 rats, males and females, in terms of their corticosterone (CORT) or behavioural responses to a range of behavioural tasks, where each of the tasks used contains a stressor component and has been demonstrated to be sensitive to corticotropin releasing factor (CRF) and/or CORT manipulation: acoustic startle response (ASR), elevated plus maze, schedule-induced polydipsia, and fear-conditioned suppression of drinking. Our aim was to determine to what extent the LEW trait of HPA axis hyporesponsiveness is associated with strain differences in behavioural responsiveness to environmental challenge. As expected, young (2-3 months)-mature (5-10 months) LEW males and females exhibited a lesser CORT response to restraint and novel confinement than did F344 males and females, although in old adulthood (18 months) the CORT stress response was equable in LEW/F344 males and actually higher in LEW than in F344 females. In young-mature adults, the ASR was greater in LEW males than in the other groups; all groups spent a low proportion of time on the open arms of the elevated plus maze; polydipsia was greater in F344 females than in the other groups; and fear-conditioned suppression of drinking was greater in F344 males and females than in LEW males and females. Therefore, relative hyporeactivity of the HPA axis in LEW rats is clearly not associated with uniform behavioural hyporeactivity, including CRF-dependent behaviours. Rather, this study suggests further evidence that environmental reactivity reflects a number of distinct emotional states and underlying neural circuits.

The maternal separation paradigm and adult emotionality and cognition in male and female Wistar rats.

A single 24-h maternal separation (MS) in the rat during the stress hyporesponsive period alters adult behavior and neuroendocrine stress response. The age of the animal at MS might be a crucial factor for effects in adulthood. We report here on adult behavioral effects of MS performed on postnatal day 4 (MS4), 9 (MS9), or 18 (MS18) in male and female Wistar rats. Unrelated subjects were used to avoid confounding litter effects. Subjects were tested on paradigms of unconditioned fear/anxiety, i.e., open field and elevated plus-maze, and on paradigms involving learning in an aversive situation, i.e., conditioned freezing, active avoidance, and water maze. In line with our predictions we obtained (a) sex differences that were consistent with enhanced fear/anxiety in males relative to females, (b) evidence that MS4 yielded deficits in active avoidance learning and conditioned freezing (trend level), whereas MS9 yielded enhanced active avoidance and water maze learning, (c) evidence (at trend level) that these effects of MS are greater in males than in females. There was no evidence for an effect of MS on paradigms of unconditioned fear/anxiety. We conclude that MS, irrespective of the age at separation, does not provide a robust environmental model of modified behavior in aversive situations.

Effect of sex on fear conditioning is similar for context and discrete CS in Wistar, Lewis and Fischer rat strains.

Enhanced fear in males relative to females, both innate and conditioned, is a well-described characteristic of behavior in the laboratory rat. In the case of aversive conditioning to foot shock in Long-Evans rats, it has been described that conditioning to general (nondiscrete) contextual cues is greater in male rats relative to female rats, whereas conditioning to a discrete, predictive stimulis (CS) is not. These findings have been combined with evidence for greater levels of hippocampal LTP in males in Sprague-Dawley rats to derive a model of hippocampal-LTP-mediated contextual and not CS, fear conditioning. The present study reports on an analysis of the effect of sex in contextual and discrete CS conditioning to foot shock, assessed via measurement of freezing behavior in a novel automated paradigm, in three rat strains: Wistar, Fischer, and Lewis. In Wistar rats, there was a consistent but nonsignificant tendency for males to demonstrate both more contextual and more CS conditioning than females; in Fischer rats, males demonstrated both more contextual and more CS conditioning than females; in Lewis rats, a markedly enhanced acquisition of freezing in males did not translate into a sex difference in either context or CS conditioning at expression. Therefore, within each strain the effect of sex was consistent between context and CS conditioning. These findings, taken together with the hippocampal LTP evidence, suggest that the latter mediates both contextual and discrete CS aversive conditioning, and contributes to sex differences in both these forms of conditioning, in those strains where these sex differences exist.

Hematology and serum chemistry values in captive Goeldi's monkeys (Callimico goeldii).

Hematologic and biochemical reference values were obtained from 27 healthy, captive, nonanesthetized Goeldi's monkeys (Callimico goeldii), a threatened South American primate, using automated techniques. The merits of nonparametric statistical analysis of values over the more common parametric method were demonstrated.

Hormonal monitoring of age at sexual maturation in female Goeldi's monkeys (Callimico goeldii) in their family groups.

The aim of this study was to determine whether or not sexual maturation is attained in the family group in captive-born Goeldi's monkey (Callimico goeldii) and if so, at what age and body weight. To monitor ovarian activity in 14 female Goeldi's monkeys, urinary content of pregnanediol-3alpha-glucuronide (PdG) was determined using radioimmunoassay. Urinary samples were collected between the ages of 6 and 70 weeks. Subjects became sexually mature while still housed in their family groups, at a median age of 57 weeks (48-< 70 weeks). Median body weight at the age of sexual maturity was 473 g (N=10; 420-543 g). This corresponded to 90% of the median non-pregnant body weight of breeding females in our colony (526 g, N=8). Therefore, Goeldi's monkey is similar to Leontopithecus but different from Cebuella, Callithrix, and Saguinus, in terms of daughters ovulating in the family group and at a relatively young age.

Continuing water fluoridation in the City of Calgary, Alberta, 1997-1998.

The issue of water fluoridation has a long history in the City of Calgary (population 820,000). There were five plebiscites before 1998, with only the 1989 plebiscite receiving a majority vote in favour of fluoridation. Calgary introduced water fluoridation in 1991. In the fall of 1997, the City sponsored a review of water fluoridation as a public policy based on information provided by a group of concerned citizens. An expert panel was formed to look at the new scientific information on the subject; four of the five members agreed that there was not sufficient evidence upon which to make substantial changes to the water fluoridation policy. Nevertheless, the City's Standing Policy Committee on Operations and Environment recommended that a plebiscite on water fluoridation be held in conjunction with the 1998 municipal election. This decision was ultimately supported by City Council. Under the direction of the Calgary Regional Health Authority, the Fluoride Education Steering Committee undertook three strategies for the campaign: building partnerships, educating health professionals and educating the public. In spite of the anti-fluoridation activities, Calgarians voted 55 per cent in favour of continuing fluoridation of the municipal water supply.