Marital Strain, Support, and Alcohol Use: Results from a Twin Design Statistically Controlling for Genetic Confounding

Background: Marriage is one of the most frequently examined sources of social support and has been shown to protect against alcohol use and abuse. This study examines the relationship between perceived marital strain and support, and alcohol use controlling for additive genetic influence. Methods: Data from monozygotic (MZ) (n = 320) and dizygotic (DZ) (n = 464) twin pairs from the second wave of the National Survey of Midlife Development in the United States (MIDUS II) were used to test whether past year marital strain and support were associated with recent alcohol use. Generalized linear mixed models (GLMM) were estimated, allowing us to control for additive genetic and shared environmental influences as variance components. Results: Marital strain and support had positive, statistically significant associations with alcohol use. However, only the relationship between marital strain and alcohol use remained after controlling for variance in alcohol use attributed to genetics. Conclusions: After accounting for genetics, midlife adults still appear to cope with marital strain via alcohol use. However, this coping is unlikely to result in heavy episodic drinking or alcohol use disorder without other compounding factors.

Crime Victimization in Latin America and Intentions to Migrate to the United States

Among the challenges faced by Latin America at the onset of the 21st century is the increase in crime and violence that began in the mid-1980s, and which, to one degree or another, has afflicted most countries in the region. In this study we explore the potential implications of the upsurge in crime on migration by testing the hypothesis that crime victimization in Latin America increases the probability that people have given serious thought to the prospect of migrating with their families to the United States. Using Latinobarometro public opinion surveys of approximately 49,000 respondents residing in 17 countries in 2002, 2003, and 2004, the results of a Hierarchical Generalized Linear Model found that, net of individual and country-level control variables, the probability of seriously considering family migration to the United States was around 30 percent higher among respondents who reported that they or a member of their family was a victim of a crime sometime during the year prior to the survey. Evidence that victimization promotes the propensity to emigrate is a finding that contributes to an understanding of the transnational consequences of the increase in crime in Latin America, and adds a new variable to the inventory of factors that encourage people to migrate to the United States.

Childhood psychopathic personality and callous-unemotional traits in the prediction of conduct problems

This study analyzed data from a prospective longitudinal study of Swedish preschoolers to examine whether psychopathic traits and concurrent conduct problems predict future conduct problems (CP) across 1- and 2-year follow-ups into early childhood. We tested the predictive ability of psychopathic traits while controlling for concurrent CP, and also by combining psychopathic traits with concurrent CP. A community sample of 1,867 preschoolers (47% girls) ages 3 to 5 years at baseline was recruited from a Swedish medium-sized municipality. Results from multivariate regression analyses showed that psychopathic traits alone (without co-occurring CP) did not consistently predict continuing childhood CP, but did so, among both boys and girls, in combination with concurrent conduct problems. It is important to note that, the combination of concurrent CP and the entire psychopathic personality, that is, a 3-dimensional psychopathic construct, was a stronger predictor of continuing childhood CP than the combination of concurrent CP and Callous-Unemotional (CU) traits among boys but not among girls. (PsycINFO Database Record

Neuroprotective effect of epidermal growth factor plus growth hormone-releasing peptide-6 resembles hypothermia in experimental stroke

BACKGROUND

Combined therapy with epidermal growth factor (EGF) and growth hormone-releasing peptide 6 (GHRP-6) in stroke models has accumulated evidence of neuroprotective effects from several studies, but needs further support before clinical translation. Comparing EGF + GHRP-6 to hypothermia, a gold neuroprotection standard, may contribute to this purpose.

OBJECTIVES

The aims of this study were to compare the neuroprotective effects of a combined therapy based on EGF + GHRP-6 with hypothermia in animal models of (a) global ischemia representing myocardial infarction and (b) focal brain ischemia representing ischemic stroke.

METHODS

(a) Global ischemia was induced in Mongolian gerbils by a 15-min occlusion of both carotid arteries, followed by reperfusion. (b) Focal brain ischemia was achieved by intracerebral injection of endothelin 1 in Wistar rats. In each experiment, three ischemic treatment groups - vehicle, EGF + GHRP-6, and hypothermia - were compared to each other and to a sham-operated control group. End points were survival, neurological scores, and infarct volume.

RESULTS

(a) In global ischemia, neurological score at 48-72 h, infarct volume, and neuronal density of hippocampal CA1 zone in gerbils treated with EGF + GHRP-6 were similar to the hypothermia-treated group. (b) In focal ischemia, the neurologic score and infarct volume of rats receiving EGF + GHRP-6 were also similar to animals in the hypothermia group.

DISCUSSION

With hypothermia being a good standard neuroprotectant reference, these results provide additional proof of principle for EGF and GHRP-6 co-administration as a potentially neuroprotective stroke therapy.

The cycle of victimization: The relationship between childhood maltreatment and adolescent peer victimization

Child maltreatment has been demonstrated to have many short- and long-term harmful consequences for victims, but whether or not child abuse is associated with an increased risk of peer victimization during adolescence is unclear. This study analyzed prospective data from 831 children and parents participating in the Longitudinal Studies on Child Abuse and Neglect (LONGSCAN) to investigate the relationships between child physical and sexual abuse and adolescent victimization by peers, as well as the potential for gender to moderate these relationships. Results from ordinal logit regression models indicated that children who were physically abused prior to age 12, based on official reports, parent reports, and child reports, had a greater risk of experiencing more intimidation and physical assault by peers at age 16. Having a history of sexual abuse predicted more physical assault but not intimidation. There was no evidence that gender moderated these relationships; in all cases, the relationship between abuse and revictimization was similar for boys and girls. The findings emphasize the need to provide victims of abuse with assistance to help prevent a cycle of victimization.

Genetic Modification of the Relationship between Parental Rejection and Adolescent Alcohol Use

AIMS

Parenting practices are associated with adolescents' alcohol consumption, however not all youth respond similarly to challenging family situations and harsh environments. This study examines the relationship between perceived parental rejection and adolescent alcohol use, and specifically evaluates whether youth who possess greater genetic sensitivity to their environment are more susceptible to negative parental relationships.

METHODS

Analyzing data from the National Longitudinal Study of Adolescent Health, we estimated a series of regression models predicting alcohol use during adolescence. A multiplicative interaction term between parental rejection and a genetic index was constructed to evaluate this potential gene-environment interaction.

RESULTS

Results from logistic regression analyses show a statistically significant gene-environment interaction predicting alcohol use. The relationship between parental rejection and alcohol use was moderated by the genetic index, indicating that adolescents possessing more 'risk alleles' for five candidate genes were affected more by stressful parental relationships.

CONCLUSIONS

Feelings of parental rejection appear to influence the alcohol use decisions of youth, but they do not do so equally for all. Higher scores on the constructed genetic sensitivity measure are related to increased susceptibility to negative parental relationships.

Using a Group-Based Trajectory Approach to Assess Risk and Protective Factors of Marijuana Use

Marijuana is the most widely used illegal substance in the world, and persistent and frequent use during adolescence has been associated with precocious transitions and deleterious consequences in adulthood. This study used a group-based trajectory approach to analyze panel data collected from 1,725 youth participating in the National Youth Study to describe pathways of marijuana use and to explore protective factors that may reduce the continuation of use. A trajectory approach allowed us to operationalize risk based on prior within-person patterns of self-reported marijuana use. Three trajectory groups of marijuana users were identified: chronic users (17%), rising users (40%), and abstainers (43%). Our results show that some protective factors are significantly associated with decreases in marijuana use for each trajectory group (e.g., parent disapproval and non-using peer associations), but others are significantly associated with decreases in marijuana for a particular trajectory group and not others (e.g., school attachment for chronic marijuana users). The implications of our findings are discussed for the risk and protective factor framework, as well as their importance in a society where opinions of marijuana are currently changing.

The effects of police contact on trajectories of violence: a group-based, propensity score matching analysis

This study uses a life course framework to investigate how police contacts may serve as a potential turning point in a violent crime trajectory. Drawing on the central ideas from deterrence and labeling theories, we determine whether individuals on different violent offending trajectories increase or decrease their offending following a police contact. Analyzing nine waves of data from the Rochester Youth Development Study, an integrated propensity score matching and latent class growth model was used. First, three violent trajectory groups emerged including high offenders, non-offenders, and low offenders. Second, after accounting for selection bias using propensity score matching procedures, experiencing a police contact increased the likelihood of future violent offending for the entire sample and for those who were on a low violent-offending trajectory specifically. These findings are interpreted as partial support for labeling theory. Limitations of the study and directions for future research are discussed.

Undergraduates achieve learning gains in plant genetics through peer teaching of secondary students

This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non-majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS) students through a case study curriculum to discover the cause of a green tomato variant. The curriculum explored plant reproduction and genetic principles, highlighting variation in heirloom tomato fruits to reinforce the concept of the genetic basis of phenotypic variation. HS students were taught additional activities related to mole-cular biology techniques not included in the MS curriculum. We measured undergraduates' learning outcomes using pre/postteaching content assessments and the course final exam. Undergraduates showed significant gains in understanding of topics related to the curriculum they taught, compared with other course content, on both types of assessments. Undergraduates who taught HS students scored higher on questions specific to the HS curriculum compared with undergraduates who taught MS students, despite identical lecture content, on both types of assessments. These results indicate the positive effect of service-learning peer-teaching experiences on undergraduates' content knowledge, even for non-science major students.

Avoiding violent victimization among youths in urban neighborhoods: the importance of street efficacy

OBJECTIVES

We investigated how street efficacy--the perceived ability to avoid dangerous and unsafe situations--is related to violent victimization across different levels of neighborhood disadvantage.

METHODS

We used 2 waves of self-report data collected between 1995 and 1999 from 1865 youths in the 9-, 12-, and 15-year-old cohorts of the Project on Human Development in Chicago Neighborhoods to measure violent victimization, street efficacy, and risk factors for violent victimization. We also analyzed data from the 1990 US Census to measure categories of neighborhood concentrated disadvantage for which the cohorts of youths reside. We used logistic regression models to examine the association between street efficacy and violent victimization while we controlled for demographic, family and parenting, self-control, and behavioral and lifestyle variables.

RESULTS

Logistic regression results showed that street efficacy had its strongest association with violent victimization in the most disadvantaged neighborhoods (odds ratio = 0.700; 95% confidence interval = 0.55, 0.89).

CONCLUSIONS

Our findings support the need to teach youths ways to successfully navigate potentially violent situations in environments that pose moderate to high risks for exposure to violence.

Progesterone and cerebral ischaemia: the relevance of ageing

Cerebral stroke is a leading cause of long-term disability and a major cause of death in the developed world. The total incidence of stroke is projected to rise substantially over the next 20 years as a result of the rising elderly population. Although age is one of the most significant prognostic markers for poor outcome after stroke, very few experimental studies have been conducted in aged animals. Importantly, sex differences in both vulnerability to stroke and outcome after cerebral ischaemia have frequently been reported and attributed to the action of steroid hormones. Progesterone is a candidate neuroprotective factor for stroke, although the majority of pre-clinical studies have focused on using young, healthy adult animals. In terms of cerebral stroke, males and postmenopausal females represent the groups at highest risk of cerebral stroke and these categories can be modelled using either aged or ovariectomised female animals. In this review, we discuss the importance of conducting experimental studies in aged animals compared to young, healthy animals, as well as the impact this has on experimental outcomes. In addition, we focus on reviewing the studies that have been conducted to date examining the neuroprotective potential of progesterone in aged animals. Importantly, the limited studies that have been conducted in aged animals do lend further support to progesterone as a therapeutic option after ischaemic stroke that warrants further investigation.

Allopregnanolone protects against dopamine-induced striatal damage after in vitro ischaemia via interaction at GABA A receptors

Sex steroid hormones, such as progesterone, have been shown to display neuroprotective properties after various models of central nervous system injury, including cerebral ischaemia, although the mechanism(s) of action remain largely undetermined. Allopregnanolone, an active progesterone metabolite, may explain some of the protective actions of progesterone. We utilised an in vitro model of ischaemia to evaluate the neuroprotective potential of allopregnanolone and examine its interaction at the GABA(A) receptor, which is hypothesised to be its main neuroprotective mechanism. In adult male mouse coronal caudate slices exposed to oxygen glucose deprivation (OGD), we measured aspects of OGD-induced dopamine release, which is neurotoxic during ischaemia, using fast cyclic voltammetry and also assessed tissue viability. The GABA(A) agonist, muscimol, displayed a neuroprotective profile in terms of delaying the OGD-evoked dopamine efflux (P < 0.05) and reducing the amount of dopamine released after OGD (P < 0.05). Allopregnanolone, at a concentration of 10(-6)  m, also displayed a neuroprotective profile because it significantly reduced the amount of dopamine efflux (P < 0.05) and reduced the loss of viable tissue after OGD compared to slices exposed to vehicle during OGD (P < 0.05). However, the effect of 10(-6)  m allopregnanolone on dopamine efflux was prevented in the presence of bicuculline, a competitive GABA(A) receptor antagonist. These results describe the use of an in vitro model of ischaemia with respect to determining that allopregnanolone is neuroprotective during the acute phase of ischaemia, and also demonstrate that such actions are dependent, at least in part, upon interaction at the GABA(A) receptor.

Prenatal exposure to cigarette smoke and childhood externalizing behavioral problems: a propensity score matching approach

We examined the possibility that the association between maternal smoking during pregnancy and childhood behavioral problems is the result of confounding. Data from the first three waves of the Fragile Families and Child Wellbeing Study were analyzed. We estimated the association between maternal smoking during pregnancy and externalizing problems in three-year olds using a propensity score matching approach. After successfully matching children based on their mother's propensities to smoke during pregnancy, the results indicate that maternal cigarette smoking is related to childhood externalizing behavioral problems, but only among mothers who smoked more than a pack per day while pregnant. At lower levels of exposure, the association between exposure to cigarette smoke in utero and externalizing behavioral problems in childhood can be explained by confounding. The results of this study support prevention efforts intended to reduce prenatal exposure to cigarette smoke, especially by mothers who smoke heavily.

Genetic Influences on Adolescent Eating Habits

Behavioral genetic research shows that variation in eating habits and food consumption is due to genetic and environmental factors. The current study extends this line of research by examining the genetic contribution to adolescent eating habits. Analysis of sibling pairs drawn from the National Longitudinal Study of Adolescent Health (Add Health) revealed significant genetic influences on variance in an unhealthy eating habits scale ( h2 = .42), a healthy eating habits scale ( h2 = .51), the number of meals eaten at a fast-food restaurant ( h2 = .33), and the total number of meals eaten per week ( h2 = .26). Most of the remaining variance was due to nonshared environmental factors. Additional analyses conducted separately for males and females revealed a similar pattern of findings. The authors note the limitations of the study and offer suggestions for future research.

The Influence of Health Strain on the Initiation and Frequency of Substance Use in a National Sample of Adolescents

Using Agnew's general strain theory (GST) as a theoretical framework, we make an argument that health problems are sources of strain that influence substance use. Health strain's influence on the initiation and frequency of substance use is then empirically investigated using two waves of data from the National Longitudinal Study of Adolescent Health (Add Health). Results from logistic and zero inflated negative binomial (ZINB) regression models show that health related strains affect the initiation of marijuana, cocaine, and other drug use, but were inconsistently associated with the frequency of use of these substances. Adolescents with more frequent minor health problems experience greater levels of strain and may choose to cope with this strain through abusing both licit and illicit substances. In some instances negative affect mediates the effects of health strain on initiation and frequency of use. Study limitations and future directions for research on health strain are discussed.

A New Trick for an Old Dog: Applying Developmental Trajectories to Inform Drug Use Progression

The frequent criticisms of the “gateway hypothesis” have led scholars to note the importance of considering the role of intra-individual change for drug use progression. While studies employing drug use trajectories have added considerably to our understanding of drug use comorbidity, the extent to which trajectories inform drug use progression remains largely unknown despite the fact that there are several theoretical reasons to suspect that intra-individual change is important to the gateway phenomenon. The current study employs latent class growth models using a sample from the Boys Town study of adolescent drug and drinking behavior. The results demonstrate that knowing how gateway drug use changes over time provides important information above and beyond knowing frequency of gateway use for predicting harder drug use trajectories. Implications of the empirical findings and directions for future research are discussed.

A gene X environment interaction between DRD2 and religiosity in the prediction of adolescent delinquent involvement in a sample of males

Human behavioral phenotypes are the result of complex interactions between genotype and the environment. Still, much remains unknown about the gene X environmental basis to adolescent delinquent involvement. Using data from the National Longitudinal Study of Adolescent Health, we examine whether a polymorphism in the dopamine D2 receptor (DRD2) gene interacts with religiosity to predict variation in adolescent delinquent involvement. The results of the analyses revealed a gene X environment interaction between the A-1 allele of DRD2 and religiosity in the prediction of adolescent delinquency. Limitations are noted, and the implications of the findings are discussed.

Evidence of a gene x environment interaction in the creation of victimization: results from a longitudinal sample of adolescents

A large body of research has revealed that aggressive personality traits and violent criminal behaviors are influenced by genetic factors. Surprisingly, however, no research has been devoted to investigating the potential genetic origins to adolescent victimization. In the current study, the authors address this gap in the literature by using data from the National Longitudinal Study of Adolescent Health (Add Health) to examine whether different variants of the dopamine D2 receptor gene (DRD2) are related to victimization, net of the effects of environmental measures. The results of the multivariate models revealed a significant gene X environment interaction in the creation of victimization for White males. Specifically, DRD2 interacted with delinquent peers to predict victimization. The authors discuss the implications of these findings.

Cannabinoid activation of PPAR alpha; a novel neuroprotective mechanism

BACKGROUND AND PURPOSE

Although CB(1) receptor activation evokes neuroprotection in response to cannabinoids, some cannabinoids have been reported to be peroxisome proliferator activated receptor (PPAR) ligands, offering an alternative protective mechanism. We have, therefore, investigated the ability of a range of cannabinoids to activate PPAR alpha and for N-oleoylethanolamine (OEA), an endogenous cannabinoid-like compound (ECL), to evoke neuroprotection.

EXPERIMENTAL APPROACH

Assays of PPAR alpha occupancy and gene transactivation potential were conducted in cell-free and transfected HeLa cell preparations, respectively. In vivo estimates of PPAR alpha activation through fat mobilization and gene transcription were conducted in mice. Neuroprotection in vivo was investigated in wild-type and PPAR alpha gene-disrupted mice.

KEY RESULTS

The ECLs OEA, anandamide, noladin ether and virodhamine were found to bind to the purified PPAR alpha ligand binding domain and to increase PPAR alpha-driven transcriptional activity. The high affinity synthetic CB(1/2) cannabinoid agonist WIN 55212-2 bound to PPAR alpha equipotently with the PPARalpha agonist fenofibrate, and stimulated PPARalpha-mediated gene transcription. The phytocannabinoid delta 9 tetrahydrocannabinol was without effect. OEA and WIN 55212-2 induced lipolysis in vivo, while OEA pre-treatment reduced infarct volume from middle cerebral artery occlusion in wild-type, but not in PPAR alpha-null mice. OEA treatment also led to increased expression of the NFkappa B-inhibitory protein, Ikappa B, in mouse cerebral cortex, while expression of the NFkappa B-regulated protein COX-2 was inhibited.

CONCLUSIONS AND IMPLICATIONS

These data demonstrate the potential for a range of cannabinoid compounds, of diverse structures, to activate PPAR alpha and suggest that at least some of the neuroprotective properties of these agents could be mediated by nuclear receptor activation.

Spinal cord plasticity in response to unilateral inhibition of the rat motor cortex during development: changes to gene expression, muscle afferents and the ipsilateral corticospinal projection

In developing Wistar albino rats, ventral horn muscle afferent boutons are lost following corticospinal innervation. Motor cortex lesions rescue a proportion of these boutons and perturb activity dependent expression of cJun and parvalbumin (PV) in the spinal cord. Therefore, we tested whether activity-dependent competition between corticospinal and proprioreceptive afferents determines the balance of these inputs to motor output pathways by delivering the inhibitory GABA agonist muscimol unilaterally to the forelimb motor cortex using slow release polymer implants from postnatal day 7 (P7) coincident with corticospinal synaptogenesis. Controls received saline. Inhibition of immature cortical neurons by muscimol was confirmed with separate in vitro electrophysiological recordings. After P28, spinal cord sections were immunostained for PV, cJun and muscle afferents transganglionically labelled with cholera toxin-B (CTB). Unilateral inhibition reduced contralaterally the number of PV positive spinal cord neurons and muscle afferent boutons in the dorsolateral ventral horn, compared to controls, and significantly altered the distribution of motoneuronal cJun expression. Separately, descending tracts were retrogradely traced with CTB from the cervical hemicord contralateral to implants. Forelimb sensorimotor cortex sections were immunostained for either CTB or PV. In muscimol treated animals, significantly fewer neurons expressed PV in the inhibited hemicortex, but as many CTB labelled corticospinal neurons were present as in controls, along with an equally large corticospinal projection from contralateral to the implant, significantly greater than in controls. Unexpectedly, unilateral inhibition of the motor cortical input did not lead to an expanded muscle afferent input. Instead, this was reduced coincident with development of a bilateral corticospinal innervation.

A detrimental role for nitric oxide synthase-2 in the pathology resulting from acute cerebral injury

Nitric oxide (NO) synthesized from the inducible isoform of nitric oxide synthase (NOS-2) has been suggested to play both beneficial and deleterious roles in various neuropathologies. To define the role of nitric oxide in traumatic brain injury, we subjected male mice lacking a functional NOS-2 gene (NOS-2-/-) and their wild-type littermates (NOS-2+/+) to mild or severe aseptic cryogenic cerebral injury. Expression of NOS-2 mRNA and protein was observed in NOS-2+/+ animals following injury. Lesion volume (as measured by histology and brain imaging) and neurological outcome (using motor and cognitive behavioral paradigms) were assessed at various times after injury. While magnetic resonance imaging revealed the extent of edema of the 2 genotypes to be similar, histology showed a reduced (32%) lesion volume in severely injured NOS-2-/- compared with NOS-2+/+ mice. In addition, NOS-2-/- mice showed significant improvements in both contralateral sensorimotor deficits (grid test: p = 0.011) and cognitive function (Morris water maze: p = 0.009) after severe injury compared to their wild-type littermates. This indicates that lesion volume is reduced and neurological recovery is improved after acute traumatic injury in mice lacking a functional NOS-2 gene, and strongly suggests that the post-trauma production of NO from this source contributes to neuropathology.

Maternal cigarette smoking during pregnancy and life-course-persistent offending

Evidence exists documenting the relationship between maternal cigarette smoking and offspring criminal behavior. Although efforts to understand this relationship in a theoretical framework have only recently emerged, attempts made have been grounded in Moffitt's developmental taxonomy of antisocial behavior. Specifically, maternal cigarette smoking is generally viewed as a potential disruption in the offspring's neuropsychological development, which is subsequently associated with life-course-persistent offending. Using a birth cohort of 987 African Americans, the authors extend previous research by empirically assessing, prospectively, the link between maternal cigarette smoking and life-course-persistent offending while using different operationalizations of Moffitt's offending categorization. The authors' findings offer some support for the relationship between maternal cigarette smoking and life-course-persistent offending, which is dependent on how this concept is operationalized.

Does self-control account for the relationship between binge drinking and alcohol-related behaviours?

INTRODUCTION

Gottfredson and Hirschi's theory that there is an underlying factor accounting for all sorts of antisocial behaviour has attracted widespread theoretical and empirical attention. One of their most controversial statements is a 'generality' hypothesis, a notion that criminal, deviant and reckless acts are highly correlated because they are caused by individual differences in self-control. In this paper, we examine the extent to which self-control accounts for the relationship between two behaviours: binge drinking and involvement in alcohol-related behaviours, including criminal behaviour.

METHOD

Questionnaires were given to students at a southern US university. A final sample of 241 students (35% males, 91% whites, aged 17-40). One question concerned binge-drinking, 11 others related to other alcohol-related behaviour; a 24-item scale measured self-control and sex was recorded. A probit model was used to test the effect of low self-control on binge drinking and on other alcohol-related behaviours. It was found that self-control exhibits a positive effect on both. But binge drinking and other alcohol-related behaviours are correlated, so a further analysis using a bivariate probit model was undertaken using a naïve model (no covariates), an unconstrained model (allowing self-control to exert a unique effect on both outcomes), and a constrained model forcing self-control to be the same for both outcomes.

RESULTS

Our results suggest that while low self-control is a significant predictor of both binge drinking and alcohol-related problems, it does not fully account for the relationship between the two outcomes. In addition, separate estimation for each sex reveal a substantively different pattern of results.

DISCUSSION

Further research is needed to disentangle the differences between the sexes. Situational factors, especially in males, may account for adverse alcohol-related behaviours. Other measures of self-control are also needed.

N-methyl-D-aspartate receptor blockade during development induces short-term but not long-term changes in c-Jun and parvalbumin expression in the rat cervical spinal cord

During postnatal development, N-methyl-D-aspartate receptor (NMDA-R) expression progressively decreases in ventral and deep dorsal horns. This transient expression might play a role in activity-dependent development of segmental circuitry. NMDA-Rs were blocked unilaterally in the lower cervical spinal cord using Elvax implants that released the NMDA-R antagonist MK-801 maximally over a 2-week period from postnatal day 7 (P7) onward. At P14, the ratio of c-Jun immunoreactive motoneurons ipsilateral/contralateral to the implants was significantly increased and the ratio of parvalbumin immunoreactive neurons decreased, compared to control implants. However, at P84, MK-801-treated and control spinal cords appeared the same. Therefore, NMDA-R blockade during development only transiently altered expression of activity-dependent proteins in the spinal cord, unlike lesions to the developing motor cortex, which we have previously shown to have a permanent effect.

Plasticity in the rat spinal cord seen in response to lesions to the motor cortex during development but not to lesions in maturity

Motor cortical inputs and proprioreceptive muscle afferents largely target the same spinal cord region. This study explored the idea that during development the two inputs interact via an activity-dependent mechanism to produce mature patterns of innervation. In rats, the forelimb motor cortex was ablated unilaterally at either postnatal day 7 (P7), the beginning of corticospinal synaptogenesis in the cervical cord, or at P50. Comparisons were made with sham-operated animals. At P70, muscle afferents from the extensor digitorum communis muscle, contralateral to the lesion, were transganglionically labeled with cholera toxin B-subunit. Lower cervical spinal cord sections were immunostained for cholera toxin B, parvalbumin, and cJun. Our small lesions had no obvious effects upon forelimb function. However, developmental lesions, but not adult lesions, were shown to significantly increase the number of muscle afferent boutons present in the contralateral ventral horn, compared with sham-operated controls. Also, the ratio of parvalbumin-positive neurons contralateral/ipsilateral to the developmental lesion (but not adult lesions) was decreased and the ratio of cJun-positive motoneurons increased. Thus, an early motor cortex lesion resulted in retention of a proportion of muscle afferent synapses to the ventral horn that are known to be lost during normal development. Parvalbumin and cJun are markers of neuronal activity suggesting that spinal circuitry develops permanently altered activity patterns in response to an early cortical lesion, although this plasticity is lost in the mature animal.

A biosocial interaction in predicting early onset of offending

Research has shown several factors increase the likelihood of early onset of offending; however, interactions among prenatal risk factors and sociological factors in predicting early onset have been a neglected area of research. The purpose of this study was to test the interactive effect of material cigarette smoking during pregnancy and the absence of the father from the household in predicting early onset of offending. The longitudinal data utilized for this study of 215 inner-city, African-American youth offenders were taken from the Philadelphia portion of the Collaborative Perinatal Project. A logistic regression analysis indicated that the combined effect of maternal cigarette smoking and absence of father from the household had a significant influence in predicting early onset of offending beyond the direct effects of the independent variables while controlling for sex of youth.

Transient expression of calcitonin gene-related peptide immunoreactivity in the ventral horn of the post-natal rat cervical spinal cord

In addition to the well known expression of calcitonin gene-related peptide (CGRP) immunoreactivity in primary afferent fibers in the dorsal horn and in motoneurons, this study has demonstrated, in rat, transient CGRP immunoreactivity in fine caliber varicose axons throughout the ventral horn and in a group of neuron cell bodies in the medial ventral horn. This was first observed at post-natal day 7 (P7) and had disappeared by P21. Physiological studies in chick embryonic spinal cord have shown that CGRP modulates spontaneous activity during development [Carr, P.A., Wenner, P., 1998. Calcitonin gene-related peptide and effects on spontaneous activity in embryonic chick spinal cord. Dev. Brain Res. 106, 47-55]. Neural activity increases post-natally in rat where it may play a role in refinement of sensorimotor synapses. This activity may also be modulated by CGRP.

Retraction of muscle afferents from the rat ventral horn during development

The postnatal reorganization of rat proprioreceptive muscle afferent spinal terminal fields was explored by labelling transganglionically afferents from extensor digitorum communis with cholera toxin B sub-unit at different ages. Immunocytochemistry revealed labelled afferents in all segments examined (C4-T2) as well as retrogradely labelled motoneurones (C5-T1). Dorsal horn innervation appeared similar at all ages, but there were striking changes in the ventral horn. Many afferent boutons were seen closely apposed to labelled motoneurone proximal dendrites at postnatal day 7 (P7) and P14, but in the adult such contacts were almost entirely confined to distal dendrites. Between P7 and adult, a significant decrease in bouton density was found in the area dorsomedial to the labelled motoneurones that contained labelled dendrites and antagonist motoneurones. This anatomical reorganization may explain both the increasing stretch reflex threshold and its concomitant decrease in magnitude with age, and the reduction in excitatory connections to antagonist motoneurones, previously described in developmental neurophysiological studies.

Interaction between maternal cigarette smoking and Apgar scores in predicting offending behavior

Research has shown that various perinatal conditions increase the likelihood of offending behavior; however, results have been mixed, but interactions among perinatal risk factors in predicting offending behavior have been neglected. The purpose was to examine the interaction of maternal cigarette smoking during pregnancy and 1-min. Apgar scores at birth in predicting individuals' later offending behavior. The longitudinal data set was taken from the Philadelphia portion of the Collaborative Perinatal Project and consisted of 832 inner-city, African-American youths. A logistic regression analysis indicated that the combined effect of maternal cigarette smoking and low Apgar scores had a significant influence in predicting offending behavior, whereas the independent effects of the component variables did not.

3H-n.m.r. studies of multiple conformations and dynamic processes in complexes of folate and methotrexate with Lactobacillus casei dihydrofolate reductase

[7,3',5'-3H3]- and [7,9-3H3]-folic acid and [7,3',5'-3H3]methotrexate (MTX) have been prepared and 3H-n.m.r. spectra obtained for their complexes with Lactobacillus casei dihydrofolate reductase (DHFR). The 3H results confirm the presence of three pH-dependent different conformational forms in the complex DHFR.NADP+.folate. The folate benzoyl ring could be shown to be in essentially the same environment in the different forms, with the major differences being associated with the pterin ring. The appearance of a single resonance for the 3',5'-tritons showed that the benzoyl ring is flipping rapidly in all three forms. In contrast, the MTX complex was shown to exist as a single conformational state with the benzoyl ring flipping rate being too low to give a single averaged signal for the 3',5'-nuclei over the temperature range 283-313 K.

Active transport of amino acids by gamma-glutamyl transpeptidase through Caco-2 cell monolayers

The possible role of the gamma-glutamyl cycle in the transport of amino acids, using the Caco-2 cell monolayer as an in vitro model of the small intestine, has been investigated. The transport of [2-3H]glycine and [2-3H]glycylglycine through the Caco-2 monolayer has been shown to occur by two modes of action. Active transport is unidirectional from apical to basolateral region and is a carrier mediated system. The enzyme gamma-glutamyl transpeptidase seems to be involved in this process, since when the enzyme is inhibited, the active transport is also inhibited. However transport still takes place, and this occurs by a slower non-active process, which is bidirectional and is mediated by passive diffusion. The rate of transport of [2-3H]glycylglycine and [2-3H]glycine were 585 (+/- 24) and 287 (+/- 16) pmolcm-2min-1 respectively, while the non-active transport takes place at 87 (+/- 6) pmolcm-2min-1. Thus, amino acid translocation in Caco-2 cells is shown to occur by two methods, one of which involves the gamma-glutamyl cycle.