Inpatient magnetic resonance cholangiopancreatography: does it increase the efficiency in emergency hepatopancreaticobiliary surgery services?

INTRODUCTION Magnetic resonance cholangiopancreatography (MRCP) is commonly used to evaluate the biliary tree, although indications for patients who require inpatient imaging are not fully defined. The aim of this study was to evaluate inpatient MRCP performed on surgical patients and to devise a treatment pathway for these patients. MATERIAL AND METHODS All adult inpatient MRCP examinations between January 2012 and December 2013 were reviewed. Demographic, clinical and radiological data were collated. RESULTS During the study period, 271 inpatient MRCP were requested, of which 234 examinations were included. The majority of patients were female (n=140) and the median age was 63 years (range 16-93 years). Surgical admissions accounted for 171 (73%) of cases. Indications for inpatient MRCP include gallstone-related complications (n=173; 74%), malignant process (n=17; 7%) and other indications (n=44; 19%). Overall, inpatient MRCP led to further inpatient interventions in 22% (gallstone group, n=32, 18%; patients with malignancy, n=8, 47%; other indications, n=12, 27%). The median duration of inpatient MRCP from request to examination was 2 days (range 0-15 days) and median reporting after examination was 1 day (range 0-14 days). DISCUSSION AND CONCLUSION Improved access and timely reporting of iMRCP may reduce length of hospital stay. Inpatient MRCP also led to further inpatient interventions, in particular, in patients with malignancy.

Depression and PTSD in Survivors of Male Violence: Research and Training Initiatives to Facilitate Recovery

Male violence is an enduring feature of women's lives from childhood through old age. The review covers child sexual abuse, rape, and partner violence with emphasis on the prevalence of violence, its mental health consequences, the course of recovery, and mediators and moderators of traumatic impact. The primary focus is depression and posttraumatic stress disorder, the two major diagnostic entities through which postassault emotions and behaviors have been conceptualized and measured. The effects of psychiatric conceptualizations of victimization and patterns of individual recovery are critically reviewed. The PTSD paradigm as the sole foundation for most victimization research is also debated. Following the review, mental health services for victimized women are examined. The article concludes with public policy recommendations to improve the availability and accessibility of mental health services with emphasis on reaching those survivors who are less likely to consult the formal system.

Parental Alcohol Use, Parenting, and Child On-Time Development

This study examined whether parental alcohol use in adolescence, adulthood, and, for mothers, during pregnancy was related to their young children's functioning in terms of their on-time development as indicated by the number of developmental areas in which children experienced delay. Observed parenting practices and family socioeconomic status were tested as potential explanatory mechanisms of these links. Data came from the surveys and videotaped observations of a community sample of 123 biological parents and their 1-5 year old children followed longitudinally. Results suggest that the negative association between parental alcohol use and children's development operates primarily through fathers' alcohol use. Additionally, father's adolescent regular alcohol use predicted the family's low SES, which in turn predicted less-skilled maternal parenting practices and children's developmental delay.

Marijuana Legalization and Parents' Attitudes, Use, and Parenting in Washington State

PURPOSE

The recent legalization of nonmedical marijuana use in several U.S. states has unknown implications for those who are actively parenting. This study examined parents' reactions to marijuana legalization and changes in attitudes and behaviors over time.

METHODS

Data were from a gender-balanced, ethnically diverse sample of 395 parents in Washington State who were participating in the longitudinal Seattle Social Development Project. Participants were interviewed 15 times between 1985 (age 10) and 2014 (age 39). Adult nonmedical marijuana use was legalized in Washington in 2012 and retail outlets opened in 2014.

RESULTS

Results showed (1) one third of parents incorrectly believed the legal age of nonmedical marijuana use to be 18; (2) significant increase in approval of adult marijuana use and decrease in perceived harm of regular use; (3) wide opposition to teen use and use around one's children; and (4) substantial increases in frequency of use and marijuana use disorder among parents who used.

CONCLUSIONS

Despite increased acceptance and frequency of adult use, parents remain widely opposed to teen use but need facts and strategies for talking with their children about marijuana.

Functional conservation of MBD proteins: MeCP2 and Drosophila MBD proteins alter sleep

Proteins containing a methyl-CpG-binding domain (MBD) bind 5mC and convert the methylation pattern information into appropriate functional cellular states. The correct readout of epigenetic marks is of particular importance in the nervous system where abnormal expression or compromised MBD protein function, can lead to disease and developmental disorders. Recent evidence indicates that the genome of Drosophila melanogaster is methylated and two MBD proteins, dMBD2/3 and dMBD-R2, are present. Are Drosophila MBD proteins required for neuronal function, and as MBD-containing proteins have diverged and evolved, does the MBD domain retain the molecular properties required for conserved cellular function across species? To address these questions, we expressed the human MBD-containing protein, hMeCP2, in distinct amine neurons and quantified functional changes in sleep circuitry output using a high throughput assay in Drosophila. hMeCP2 expression resulted in phase-specific sleep loss and sleep fragmentation with the hMeCP2-mediated sleep deficits requiring an intact MBD domain. Reducing endogenous dMBD2/3 and dMBD-R2 levels also generated sleep fragmentation, with an increase in sleep occurring upon dMBD-R2 reduction. To examine if hMeCP2 and dMBD-R2 are targeting common neuronal functions, we reduced dMBD-R2 levels in combination with hMeCP2 expression and observed a complete rescue of sleep deficits. Furthermore, chromosomal binding experiments indicate MBD-R2 and MeCP2 associate on shared genomic loci. Our results provide the first demonstration that Drosophila MBD-containing family members are required for neuronal function and suggest that the MBD domain retains considerable functional conservation at the whole organism level across species.

Associations Between Parental and Grandparental Marijuana Use and Child Substance Use Norms in a Prospective, Three-Generation Study

PURPOSE

Using prospective longitudinal data from three generations, this study seeks to test whether and how parent and grandparent marijuana use (current and prior) predicts an increased likelihood of child cigarette, alcohol, and marijuana use.

METHODS

Using multilevel modeling of prospective data spanning three generations (n = 306 families, children ages 6-22), this study tested associations between grandparent (G1) and parent (G2) marijuana use and child (G3) past-year cigarette, alcohol, and marijuana use. Analyses tested whether G3 substance-related norms mediated these associations. Current G1 and G2 marijuana use was examined, as was G2 high school and early adult use and G1 marijuana use when G2 parents were in early adolescence. Controls included G2 age at G3 birth, G2 education and depression, and G3 gender.

RESULTS

G2 current marijuana use predicted a higher likelihood of G3 alcohol and marijuana use but was not related to the probability of G3 cigarette use. G3's perceptions of their parents' norms and G2 current marijuana use both contributed independently to the likelihood of G3 alcohol and marijuana use when included in the same model. G3 children's own norms and their perceptions of friends' norms mediated the link between G2 current marijuana use and G3 alcohol and marijuana use.

CONCLUSIONS

Results are discussed in light of the growing trend toward marijuana legalization. To the extent that parent marijuana use increases under legalization, we can expect more youth to use alcohol and marijuana and to have norms that favor substance use.

Unemployment and substance use problems among young adults: Does childhood low socioeconomic status exacerbate the effect?

The current study tested whether unemployment predicted young adults' heavy episodic drinking, cigarette smoking, and cannabis use after taking into account individual development in substance use. Furthermore, building on the life course perspective, this study examined whether the link between unemployment and substance use among young adults differed for those who experienced low childhood SES compared to those who did not. Data for the present study came from the Seattle Social Development Project (SSDP), a panel study examining a broad range of developmental outcomes from ages 10 to 33. A life history calendar (LHC) was administered to assess substance use and unemployment status during young adulthood. Covariates included baseline symptoms of psychopathology, baseline substance use, gender, ethnicity, and adult educational attainment. Results suggest that unemployment is associated with young adults' heavy episodic drinking and possibly cigarette use, but not cannabis use. Moreover, for all three substances, the detrimental impact of unemployment on substance use seems to be exacerbated among young adults who spent their childhood and adolescence in a lower SES household. Public health efforts that provide other viable and affordable options to cope with unemployment among young adults from low SES backgrounds are needed to address this disproportionate concentration of adverse impacts of unemployment on behavioral health.

Trajectories of marijuana use from adolescence into adulthood: Environmental and individual correlates

This study sought to identify trajectories of marijuana use in the Seattle Social Development Project (n = 808) sample from age 14 through 30, and to examine the extent to which individuals in these trajectories differed in their substance use problems, mental health, problem behavior, economic outcomes, and positive functioning at age 33. In addition, analyses examined between-trajectory differences in family, peer, school, neighborhood, individual, mental health, and substance use factors at key developmental points in adolescence and adulthood. Four trajectories of marijuana use were identified: nonusers (27%), adolescent-limited (21%), late-onset (20%), and chronic (32%) users. At age 33, the chronic trajectory was associated with the worst functioning overall. The late-onset group reported more substance use and sexual risk behavior than nonusers, but was otherwise not differentiated. The adolescent-limited group reported significantly lower educational and economic outcomes at age 33 than the late-onset and nonuser groups. In analyses at earlier ages, adolescent-limited and late-onset groups reported more problems in functioning during the period of escalation in use and improvement in functioning with the beginning of desistance. Implications for prevention are discussed, particularly the unique risks associated with early adolescent versus later onset of marijuana use.

Regional cerebellar volumes are related to early musical training and finger tapping performance

The cerebellum has been associated with timing on the millisecond scale and with musical rhythm and beat processing. Early musical training (before age 7) is associated with enhanced rhythm synchronization performance and differences in cortical motor areas and the corpus callosum. In the present study, we examined the relationships between regional cerebellar volumes, early musical training, and timing performance. We tested adult musicians and non-musicians on a standard finger tapping task, and extracted cerebellar gray and white matter volumes using a novel multi-atlas automatic segmentation pipeline. We found that early-trained musicians had reduced volume in bilateral cerebellar white matter and right lobules IV, V and VI, compared to late-trained musicians. Strikingly, better timing performance, greater musical experience and an earlier age of start of musical training were associated with smaller cerebellar volumes. Better timing performance was specifically associated with smaller volumes of right lobule VI. Collectively, these findings support the sensitivity of the cerebellum to the age of initiation of musical training and suggest that lobule VI plays a role in timing. The smaller cerebellar volumes associated with musical training and timing performance may be a reflection of more efficiently implemented low-level timing and sensorimotor processes.

The onset of STI diagnosis through age 30: results from the Seattle Social Development Project Intervention

The objectives of this study were to examine (1) whether the onset of sexually transmitted infections (STI) through age 30 differed for youths who received a social developmental intervention during elementary grades compared to those in the control condition; (2) potential social-developmental mediators of this intervention; and (3) the extent to which these results differed by ethnicity. A nonrandomized controlled trial followed participants to age 30, 18 years after the intervention ended. Three intervention conditions were compared: a full-intervention group, assigned to intervention in grades 1 through 6; a late intervention group, assigned to intervention in grades 5 and 6 only; and a no-treatment control group. Eighteen public elementary schools serving diverse neighborhoods including high-crime neighborhoods of Seattle are the setting of the study. Six hundred eight participants in three intervention conditions were interviewed from age 10 through 30. Interventions include teacher training in classroom instruction and management, child social and emotional skill development, and parent workshops. Outcome is the cumulative onset of participant report of STI diagnosis. Adolescent family environment, bonding to school, antisocial peer affiliation, early sex initiation, alcohol use, cigarette use, and marijuana use were tested as potential intervention mechanisms. Complementary log-log survival analysis found significantly lower odds of STI onset for the full-intervention compared to the control condition. The lowering of STI onset risk was significantly greater for African Americans and Asian Americans compared to European Americans. Family environment, school bonding, and delayed initiation of sexual behavior mediated the relationship between treatment and STI hazard. A universal intervention for urban elementary school children, focused on classroom management and instruction, children's social competence, and parenting practices may reduce the onset of STI through age 30, especially for African Americans.

General and substance-specific predictors of young adult nicotine dependence, alcohol use disorder, and problem behavior: replication in two samples

BACKGROUND

This paper presents two replications of a heuristic model for measuring environment in studies of gene-environment interplay in the etiology of young adult problem behaviors.

METHODS

Data were drawn from two longitudinal, U.S. studies of the etiology of substance use and related behaviors: the Raising Healthy Children study (RHC; N=1040, 47% female) and the Minnesota Twin Family Study (MTFS; N=1512, 50% female). RHC included a Pacific Northwest, school-based, community sample. MTFS included twins identified from state birth records in Minnesota. Both studies included commensurate measures of general family environment and family substance-specific environments in adolescence (RHC ages 10-18; MTFS age 18), as well as young adult nicotine dependence, alcohol and illicit drug use disorders, HIV sexual risk behavior, and antisocial behavior (RHC ages 24, 25; MTFS age 25).

RESULTS

Results from the two samples were highly consistent and largely supported the heuristic model proposed by Bailey et al. (2011). Adolescent general family environment, family smoking environment, and family drinking environment predicted shared variance in problem behaviors in young adulthood. Family smoking environment predicted unique variance in young adult nicotine dependence. Family drinking environment did not appear to predict unique variance in young adult alcohol use disorder.

CONCLUSIONS

Organizing environmental predictors and outcomes into general and substance-specific measures provides a useful way forward in modeling complex environments and phenotypes. Results suggest that programs aimed at preventing young adult problem behaviors should target general family environment and family smoking and drinking environments in adolescence.

Understanding the link between early sexual initiation and later sexually transmitted infection: test and replication in two longitudinal studies

PURPOSE

Age at sexual initiation is strongly associated with sexually transmitted infections (STI); yet, prevention programs aiming to delay sexual initiation have shown mixed results in reducing STI. This study tested three explanatory mechanisms for the relationship between early sexual debut and STI: number of sexual partners, individual characteristics, and environmental antecedents.

METHODS

A test-and-replicate strategy was employed using two longitudinal studies: the Seattle Social Development Project (SSDP) and Raising Healthy Children (RHC). Childhood measures included pubertal age, behavioral disinhibition, and family, school, and peer influences. Alcohol use and age of sexual debut were measured during adolescence. Lifetime number of sexual partners and having sex under the influence were measured during young adulthood. Sexually transmitted infection diagnosis was self-reported at age 24. Early sex was defined as debut at <15 years. Path models were developed in SSDP evaluating relationships between measures, and were then tested in RHC.

RESULTS

The relationship between early sex and STI was fully mediated by lifetime sex partners in SSDP, but only partially in RHC, after accounting for co-occurring factors. Behavioral disinhibition predicted early sex, early alcohol use, number of sexual partners, and sex under the influence, but had no direct effect on STI. Family management protected against early sex and early alcohol use, whereas antisocial peers exacerbated the risk.

CONCLUSIONS

Early sexual initiation, a key mediator of STI, is driven by antecedents that influence multiple risk behaviors. Targeting co-occurring individual and environmental factors may be more effective than discouraging early sexual debut and may concomitantly improve other risk behaviors.

Sexual risk behavior in young adulthood: broadening the scope beyond early sexual initiation

A robust link between early sexual initiation and sexual risk-taking behavior is reported in previous studies. The relationship may not be causal, however, as the effect of common risk factors is often not considered. The current study examined whether early initiation was a key predictor of risky sexual behavior in the 20s and 30s, over and above co-occurring individual and environmental factors. Data were drawn from the Seattle Social Development Project, a longitudinal panel of 808 youth. Early predictors (ages 10 to 15) and sexual risk taking (ages 21 to 24 and 30 to 33) were assessed prospectively. Early sexual initiation (before age 15) was entered into a series of probit regressions that also included family, neighborhood, peer, and individual risk factors. Although a positive bivariate relation between early sexual initiation and sexual risk taking was observed at both ages, the link did not persist when co-occurring risk factors were included. Behavioral disinhibition and antisocial peer influences emerged as the strongest predictors of sexual risk over and above early sexual initiation. These results suggest that early sexual initiation must be considered in the context of common antecedents; public health policy aimed at delaying sexual intercourse alone is unlikely to substantially reduce sexual risk behavior in young adulthood.

The relationship between the age of onset of musical training and rhythm synchronization performance: validation of sensitive period effects

A sensitive period associated with musical training has been proposed, suggesting the influence of musical training on the brain and behavior is strongest during the early years of childhood. Experiments from our laboratory have directly tested the sensitive period hypothesis for musical training by comparing musicians who began their training prior to age seven with those who began their training after age seven, while matching the two groups in terms of musical experience (Watanabe et al., 2007; Bailey and Penhune, 2010, 2012). Using this matching paradigm, the early-trained groups have demonstrated enhanced sensorimotor synchronization skills and associated differences in brain structure (Bailey et al., 2013; Steele et al., 2013). The current study takes a different approach to investigating the sensitive period hypothesis for musical training by examining a single large group of unmatched musicians (N = 77) and exploring the relationship between age of onset of musical training as a continuous variable and performance on the Rhythm Synchronization Task (RST), a previously used auditory-motor RST. Interestingly, age of onset was correlated with task performance for those who began training earlier, however, no such relationship was observed among those who began training in their later childhood years. In addition, years of formal training showed a similar pattern. However, individual working memory scores were predictive of task performance, regardless of age of onset of musical training. Overall, these results support the sensitive period hypothesis for musical training and suggest a non-linear relationship between age of onset of musical training and auditory-motor rhythm synchronization abilities, such that a relationship exists early in childhood but then plateaus later on in development, similar to maturational growth trajectories of brain regions implicated in playing music.

Alcohol and tobacco use disorder comorbidity in young adults and the influence of romantic partner environments

BACKGROUND

Although there is considerable evidence that the development of tobacco dependence (TD) and that of alcohol use disorder (AUD) are intertwined, less is known about the comorbid development of these disorders. The present study examines tobacco dependence and alcohol use disorder comorbidity in young adulthood within the context of romantic partner relationships.

METHODS

Data were drawn from the Seattle Social Development Project, a contemporary, ethnically diverse, and gender balanced longitudinal panel including 808 participants. A typological person-centered approach was used to assign participants to four outcome groups: no disorder, tobacco dependence (TD) only, alcohol use disorder (AUD) only, and comorbid (both). Multinomial logistic regression was used to determine the association between partner general and substance-specific environments and single or dual alcohol and tobacco use disorder diagnosis in young adulthood (ages 24-33, n=628). Previous heavy alcohol and tobacco use were controlled for, as were dispositional characteristics, gender, ethnicity, adult SES, and adult depression.

RESULTS

Greater partner conflict increased the likelihood of being comorbid compared to having TD only or AUD only. Having a smoking partner increased the likelihood of being comorbid compared to having AUD only, but having a drinking partner did not significantly distinguish being comorbid from having TD only.

CONCLUSIONS

Findings demonstrated the utility of a comorbidity-based, person-centered approach and the influence of general and tobacco-specific, but not alcohol-specific, partner environments on comorbid alcohol and tobacco use disorders in young adulthood.

The effect of general and drug-specific family environments on comorbid and drug-specific problem behavior: a longitudinal examination

Previous research has shown that the development of alcohol and tobacco dependence is linked and that both are influenced by environmental and intrapersonal factors, many of which likely interact over the life course. The present study examines the effects of general and alcohol- and tobacco-specific environmental influences in the family of origin (ages 10-18) and family of cohabitation (ages 27-30) on problem behavior and alcohol- and tobacco-specific outcomes at age 33. General environmental factors include family management, conflict, bonding, and involvement. Alcohol environment includes parental alcohol use, parents' attitudes toward alcohol, and children's involvement in family drinking. Tobacco-specific environment is assessed analogously. Additionally, analyses include the effects of childhood behavioral disinhibition, initial behavior problems, and age 18 substance use. Analyses were based on 469 participants drawn from the Seattle Social Development Project (SSDP) sample. Results indicated that (a) environmental factors within the family of origin and the family of cohabitation are both important predictors of problem behavior at age 33; (b) family of cohabitation influences partially mediate the effects of family of origin environments; (c) considerable continuity exists between adolescent and adult general and tobacco (but not alcohol) environments; age 18 alcohol and tobacco use partially mediates these relationships; and (d) childhood behavioral disinhibition contributed to age 33 outcomes, over and above the effects of family of cohabitation mediators. Implications for preventive interventions are discussed.

Examining explanatory mechanisms of the effects of early alcohol use on young adult alcohol dependence

OBJECTIVE

This study examined potential explanatory mechanisms linking childhood alcohol use onset and chronicity of adult alcohol dependence by testing the following three competing hypotheses: (1) a marker hypothesis, where early onset of alcohol use may be simply a marker for other factors that have been linked to both age at initiation and adult alcohol problems; (2) a compromised development hypothesis, where early alcohol initiation may interfere with adolescent development, which can lead to later alcohol problems; and (3) an increased substance use hypothesis, where early onset of alcohol use may lead to increased substance use in adolescence and, in turn, chronic alcohol dependence.

METHOD

Data came from a longitudinal community sample of 808 participants recruited at age 10 in 1985. Participants were followed through age 33 in 2008 with 92% retention.

RESULTS

Childhood onset of alcohol use (before age 11), when compared with initiation during adolescence, predicted an increased chronicity of adult alcohol dependence, even after accounting for the hypothesized confounds from the marker hypothesis. In addition, adolescent compromised functioning did not mediate this relationship between early alcohol use and chronicity of adult dependence (Hypothesis 2), nor did adolescent substance use (Hypothesis 3). However, compromised functioning and substance use in adolescence predicted increased chronicity of alcohol dependence in young adulthood.

CONCLUSIONS

Prevention efforts as early as the elementary grades should focus on delaying the onset of alcohol use and reducing substance use in adolescence as well as improving school functioning, reducing adolescent problem behaviors, and targeting adolescent peer networks.

The association between parent early adult drug use disorder and later observed parenting practices and child behavior problems: testing alternate models

This study tested the association between parent illicit drug use disorder (DUD) in early adulthood and observed parenting practices at ages 27-28 and examined the following 3 theoretically derived models explaining this link: (a) a disrupted parent adult functioning model,(b) a preexisting parent personality factor model, and (c) a disrupted adolescent family process model. Associations between study variables and child externalizing problems also were examined. Longitudinal data linking 2 generations were drawn from the Seattle Social Development Project (SSDP) and The SSDP Intergenerational Project (TIP), and included 167 parents and their 2- to 8-year-old child. Path modeling revealed that parent DUD in early adulthood predicted later observed low-skilled parenting, which was related to child externalizing problems. The preexisting parent personality factor model was supported. Parent negative emotionality accounted for the association between parent early adult DUD and later parenting practices. Parent negative emotionality also was related directly to child externalizing behavior. Limited support for the disrupted transition to adulthood model was found. The disrupted adolescent family process model was not supported. Results suggest that problem drug use that occurs early in adulthood may affect later parenting skills, independent of subsequent parent drug use. Findings highlight the importance of parent negative emotionality in influencing his or her own problem behavior, interactions with his or her child, and his or her child's problem behavior. Prevention and treatment programs targeting young adult substance use, poor parenting practices, and child behavior problems should address parent personality factors that may contribute to these behaviors.

Co-occurrence of sexual risk behaviors and substance use across emerging adulthood: evidence for state- and trait-level associations

AIMS

  Prior research has suggested that problematic alcohol and drug use are related to risky sexual behaviors, either due to trait-level associations driven by shared risk factors such as sensation seeking or by state-specific effects, such as the direct effects of substance use on sexual behaviors. Although the prevalence of both high-risk sexual activity and alcohol problems decline with age, little is known about how the associations between substance use disorder symptoms and high-risk sexual behaviors change across young adulthood.

DESIGN, SETTING AND PARTICIPANTS

  Using a community sample (n = 790) interviewed every 3 years from age 21 to age 30 years, we tested trait- and state-level associations among symptoms of alcohol and drug abuse and dependence and high-risk sexual behaviors across young adulthood using latent growth curve models.

MEASUREMENTS

  We utilized diagnostic interviews to obtain self-report of past-year drug and alcohol abuse and dependence symptoms. High-risk sexual behaviors were assessed with a composite of four self-reported behaviors.

FINDINGS

  Results showed time-specific associations between alcohol disorder symptoms and risky sexual behaviors (r = 0.195, P < 0.001), but not associations between their trajectories of change. Conversely, risky sexual behaviors and drug disorder symptoms were associated only at the trait level, not the state level, such that the levels and rate of change over time of both were correlated (r = 0.35, P < 0.001).

CONCLUSIONS

  High-risk sexual behaviors during young adulthood seem to be driven both by trait and state factors, and intervention efforts may be successful if they are either aimed at high-risk individuals or if they work to disaggregate alcohol use from risky sexual activities.

Romantic relationship characteristics and alcohol use: longitudinal associations with dual method contraception use

PURPOSE

Dual method contraception use, or the use of one type of contraceptive intended to prevent pregnancy combined with another type intended to reduce the risk of sexually transmitted infection, may be the most effective method to prevent both unintended pregnancy and sexually transmitted infection. This study tested the association between relationship length, relationship type (married, cohabiting, dating but not cohabiting), global alcohol use, and situational alcohol use and the probability of dual method contraception use from 20 to 23 years of age.

METHODS

Hierarchical linear modeling analyses were conducted using longitudinal data from 754 sexually active male and female young adults aged 20-23 years. Dependent variables included both any dual method contraception use and consistent dual method contraception use.

RESULTS

Between 15% and 20% of respondents reported consistent dual method contraception use at each time point. Longer relationship length and more committed relationship type were associated with a lower probability of both any and consistent dual method contraception use. Situational alcohol use (drinking before sex), but not global alcohol use, also was related to a lower probability of both any and consistent dual method contraception use. Increasing age was associated with a lower probability of any dual method contraception use, but was not related to consistent dual method use.

CONCLUSIONS

Efforts to promote dual method contraception among young adults should include messages discouraging drinking before sex and supporting dual method use even in the context of committed relationships.

The effects of general and alcohol-specific peer factors in adolescence on trajectories of alcohol abuse disorder symptoms from 21 to 33 years

BACKGROUND

The present study examines whether general and alcohol-specific peer risk factors from age 10 to 18 are associated with longitudinal patterns of adult alcohol abuse disorder symptoms from age 21 to 33.

METHODS

Using growth mixture modeling, trajectory groups of alcohol abuse disorder symptoms from age 21 to 33 were identified. We then examined the relationships between the identified trajectory groups of alcohol abuse disorder symptoms and respondents' own adolescent binge drinking, a general negative peer factor, and an alcohol-specific peer factor (having drinking peers) in adolescence using pseudo-class Wald Chi-square tests, and multinomial logistic regressions.

RESULTS

Four different trajectory groups of alcohol abuse disorder symptoms were identified: persistor group (3%), decreaser group (23%), escalator group (3%), and a no-disorder group (71%). Bivariate Wald Chi-square tests indicated that adolescent binge drinking behavior and general and alcohol-specific peer factors differentiated the adult alcohol abuse trajectory groups. Multivariate multinomial logistic regression showed that the general negative peer factors distinguished those who later persisted in alcohol abuse from those who desisted (i.e., persistor group vs. decreaser group) during young adulthood, even after adjusting for respondents' adolescent binge drinking. On the other hand, associating with drinking peers did not distinguish these trajectories.

CONCLUSION

Alcohol-specific peer influences appear to influence alcohol abuse disorder symptoms in the early 20s, while general negative peer exposure in adolescence increases in importance as a risk factor for alcohol abuse disorder symptom persistence in the late 20s and the early 30s.

Strategies for characterizing complex phenotypes and environments: general and specific family environmental predictors of young adult tobacco dependence, alcohol use disorder, and co-occurring problems

BACKGROUND

Defining phenotypes in studies of tobacco and alcohol misuse is difficult because of the complexity of these behaviors and their strong association with each other and with other problem behaviors. The present paper suggests a strategy for addressing this issue by conceptualizing and partitioning variance in phenotypes into either general or substance/behavior-specific. The paper also applies the general or substance/behavior-specific conceptualization to environmental predictors of tobacco and alcohol misuse and other problem behaviors.

METHODS

Data were drawn from the Seattle Social Development Project, a contemporary, ethnically diverse and gender-balanced longitudinal panel including 808 participants. Latent variable modeling was used to partition variance in young adult (age 24) nicotine dependence, alcohol abuse and dependence, illicit drug abuse and dependence, involvement in crime, and engagement in HIV sexual risk behavior into general problem behavior and behavior-specific variance. Similarly, measures of general, drinking-specific, and smoking-specific adolescent family environment were constructed.

RESULTS

Consistent with expectations, more positive general family environment during adolescence was associated with lower levels of shared variance in problem behaviors at age 24, but not with unique variance in tobacco or alcohol use disorder. Higher levels of family smoking and drinking environments during adolescence, however, were positively associated with unique variance in tobacco and alcohol use disorder, respectively, but did not predict shared variance in problem behaviors.

CONCLUSIONS

Results support the utility of the proposed approach. Ways in which this approach might contribute to future molecular genetic studies are discussed.

Sensitive periods for adolescent alcohol use initiation: predicting the lifetime occurrence and chronicity of alcohol problems in adulthood

OBJECTIVE

This study examined the association between age at alcohol use onset and adult alcohol misuse and dependence by testing the sensitive-period hypothesis that early adolescence (11-14) is a vulnerable period of development during which initiating alcohol use is particularly harmful.

METHOD

Data came from a longitudinal panel of 808 participants recruited in 1981. Participants were followed through age 33 in 2008 with 92% retention.

RESULTS

Onset of alcohol use before age 11 (late childhood), when compared with initiation during early adolescence, was related to an increased chronicity of adult alcohol dependence, even after accounting for sociodemographic controls and other substance use in adolescence. The present study finds no evidence that early adolescence is a particularly sensitive period for the onset of alcohol use. Findings related to the onset of regular alcohol use and the chronicity of alcohol dependence suggest that the onset of regular drinking before age 21 is problematic, but no one adolescent period is more sensitive than others. Specifically, although all age groups that started drinking regularly before age 21 had a greater rate of alcohol dependence in adulthood, initiation of regular use of alcohol at or before age 14 was not related to greater chronicity of alcohol dependence than the initiation of regular use of alcohol in middle or late adolescence.

CONCLUSIONS

The findings suggest the importance of delaying the onset of alcohol use through prevention efforts as early as the elementary grades. In addition, prevention efforts should focus on preventing the onset of regular drinking before age 21.

Associations between changing developmental contexts and risky sexual behavior in the two years following high school

The present study tested associations between common developmental contexts (relationship involvement, independent living, college attendance, work) and risky sexual behavior (casual sex, inconsistent condom use, high-risk sex) across the 2 years following high school. Data were drawn from the Raising Healthy Children project, and included 801 participants aged 18-21 years. Longitudinal analyses, which controlled for early sexual debut, high school substance use, and high school grades, showed that living with a parent was protective against all three sexual risk behavior outcomes (ORs about 0.70). Being in a romantic relationship was associated with a lower probability of casual sex, but a higher probability of inconsistent condom use. Attending college was associated with a lower probability of high-risk sex (OR = 0.67). Working was not related to the sexual risk behaviors examined. Levels of sexual risk behavior showed little change across the 2 years following high school. Findings from this study suggest that developmental context may affect young adults' engagement in risky sexual behavior. Programs aimed at promoting sexual health and reducing risk behaviors for STIs among young adults should consider targeting those in romantic relationships, those not living with parents, and those not attending college. Further, to develop effective prevention programs for these targeted youth, it is critical that we understand the mechanisms leading to risky sex in these groups.

HPV vaccination among a community sample of young adult women

OBJECTIVES

Despite the high efficacy of the human papillomavirus (HPV) vaccine, uptake has been slow and little data on psychosocial barriers to vaccination exist.

METHODS

A community sample of 428 women enrolled in a longitudinal study of social development in the Seattle WA metropolitan area were interviewed about HPV vaccine status, attitudes, and barriers to HPV vaccination in spring 2008 or 2009 at ∼age 22.

RESULTS

Nineteen percent of women had initiated vaccination, 10% had completed the series, and ∼40% of unvaccinated women intended to get vaccinated. Peer approval was associated with vaccine initiation (adjusted prevalence ratio (APR) 2.1; 95% confidence interval 1.4-3.2) and intention to vaccinate (APR 1.4; 1.1-1.9). Belief the vaccine is <75% effective was associated with less initiation (APR 0.6; 0.4-0.9) or intention to vaccinate (APR 0.5; 0.4-0.7). Vaccine initiation was also less likely among cigarette smokers and illegal drug users, whereas intention to vaccinate was more common among women currently attending school or with >5 lifetime sex partners, but less common among women perceiving low susceptibility to HPV (APR 0.6; 0.5-0.9).

CONCLUSIONS

HPV vaccination uptake was low in this community sample of young adult women. Increasing awareness of susceptibility to HPV and the high efficacy of the vaccine, along with peer interventions to increase acceptability, may be most effective.

Men's and Women's Pathways to Adulthood and Their Adolescent Precursors

This study compared men's and women's pathways to adulthood by examining how role transitions in education, work, marriage, and parenthood intersect and form developmental pathways from ages 18-30. The study investigated how sociodemographic factors and adolescent experiences were associated with these pathways. We used latent class analysis to analyze longitudinal data from a gender-balanced panel of 808 contemporary young adults. We found three similar latent pathways for both genders, but men and women differed in the timing of marriage and when they began to live with children and the likelihood of combining both roles. The present study points to the continued, though differential, relevance of marriage and family in the transition to adulthood for men and women.

Person-environment interaction in the prediction of alcohol abuse and alcohol dependence in adulthood

BACKGROUND

Behavioral disinhibition (externalizing/impulsivity) and behavioral inhibition (internalizing/anxiety) may contribute to the development of alcohol abuse and dependence. But tests of person-by-environment interactions in predicting alcohol use disorders are needed. This study examined the extent to which interactions between behavioral disinhibition, behavioral inhibition and family management during adolescence predict alcohol abuse and alcohol dependence at age 27.

METHODS

This study used longitudinal data from a community sample of 808 men and women interviewed from ages 10 to 27 in the Seattle Social Development Project. Zero-order correlations followed by a series of nested regressions examined the relationships between individual characteristics (behavioral disinhibition and behavioral inhibition/anxiety) and environment (good vs. poor family management practices during adolescence) in predicting alcohol abuse and dependence criterion counts at age 27.

RESULTS

Behavioral disinhibition and poor family management predicted increased likelihood of both alcohol abuse and alcohol dependence at age 27. Behavioral inhibition/anxiety was unrelated to both outcomes. Youths high in behavioral disinhibition were at increased risk for later alcohol abuse and dependence only in consistently poorly managed family environments. In consistently well-managed families, high levels of behavioral disinhibition did not increase risk for later alcohol abuse or dependence.

CONCLUSIONS

Behavioral disinhibition increases risk for alcohol abuse and dependence in early adulthood only for individuals who experience poor family management during adolescence. Interventions seeking to reduce environmental risks by strengthening consistent positive family management practices may prevent later alcohol abuse and dependence among individuals at risk due to behavioral disinhibition.

Differential induction of chalcone synthase mRNA activity at the onset of phytoalexin accumulation in compatible and incompatible plant-pathogen interactions

Changes in the mRNA activity of chalcone synthase, the first enzyme of phenylpropanoid metabolism specific to flavonoid/isoflavonoid biosynthesis, have been investigated in relation to expression of the phytoalexin defense response in race-cultivar specific interactions between hypocotyls of Phaseolus vulgaris and the partially biotrophic fungus Colletotrichum lindemuthianum, causal agent of anthracnose. In an incompatible interaction (host resistant) there is an early but localized increase in chalcone synthase mRNA activity prior to the onset of accumulation of the phenylpropanoid-derived phytoalexin phaseoflin and expression of hypersensitive resistance. In contrast, in a compatible interaction (host susceptible) there is no induction of mRNA activity in the early stages of infection but rather a delayed, widespread increase during attempted lesion limitation at the onset of symptom development. The data indicate that control of phytoalexin gene expression is a key early component in the defense responses of biologically stressed cells during a race-cultivar specific host-pathogen interaction.

Accumulation of hydroxyproline-rich glycoprotein mRNAs in response to fungal elicitor and infection

Hydroxyproline-rich glycoproteins (HRGPs) are important structural components of plant cell walls and also accumulate in response to infection as an apparent defense mechanism. Accumulation of HRGP mRNA in biologically stressed bean (Phaseolus vulgaris L.) cells was monitored by blot hybridization with (32)P-labeled tomato genomic HRGP sequences. Elicitor treatment of suspension-cultured cells caused a marked increase in hybridizable HRGP mRNA. The response was less rapid but more prolonged than that observed for mRNAs encoding enzymes of phytoalexin biosynthesis. HRGP mRNA also accumulated during race:cultivar-specific interactions between bean hypocotyls and the partially biotrophic fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. In an incompatible interaction (host resistant) there was an early increase in HRGP mRNA correlated with expression of hypersensitive resistance; whereas, in a compatible interaction (host susceptible), marked accumulation of HRGP mRNA occurred as a delayed response at the onset of lesion formation. In both interactions, mRNA accumulation was observed in uninfected cells distant from the site of fungal inoculation, indicating intercellular transmission of an elicitation signal.

Prospective associations among alcohol use-related sexual enhancement expectancies, sex after alcohol use, and casual sex

Higher levels of alcohol use have consistently been related to higher rates of sexual risk taking; however, it is not clear whether this relationship is causal. This study examined the concurrent and predictive associations among alcohol use-related sexual enhancement expectancies, drinking alcohol before engaging in sex, and casual sex during the transition into emerging adulthood and whether these associations differed for men and women. Data came from 590 men and women who were interviewed 3 times at 6-month intervals after high school. Growth curve analyses indicated that alcohol-related sexual enhancement expectancies were related to casual sex indirectly through drinking before sex but did not predict change in either of these behaviors. However, increases in drinking before sex predicted increases in casual sex over time. The findings provide some support for prevention programs that focus on alcohol-related sexual expectancies to reduce sexually transmitted illnesses among emerging adults.

Parenting practices and problem behavior across three generations: monitoring, harsh discipline, and drug use in the intergenerational transmission of externalizing behavior

Using data from grandparents (G1), parents (G2), and children (G3), this study examined continuity in parental monitoring, harsh discipline, and child externalizing behavior across generations, and the contribution of parenting practices and parental drug use to intergenerational continuity in child externalizing behavior. Structural equation and path modeling of prospective, longitudinal data from 808 G2 participants, their G1 parents, and their school-age G3 children (n = 136) showed that parental monitoring and harsh discipline demonstrated continuity from G1 to G2. Externalizing behavior demonstrated continuity from G2 to G3. Continuity in parenting practices did not explain the intergenerational continuity in externalizing behavior. Rather, G2 adolescent externalizing behavior predicted their adult substance use, which was associated with G3 externalizing behavior. A small indirect effect of G1 harsh parenting on G3 was observed. Interparental abuse and socidemographic risk were included as controls but did not explain the intergenerational transmission of externalizing behavior. Results highlight the need for preventive interventions aimed at breaking intergenerational cycles in poor parenting practices. More research is required to identify parental mechanisms influencing the continuity of externalizing behavior across generations.

Human copy number polymorphic genes

Recent large-scale genomic studies within human populations have identified numerous genomic regions as copy number variant (CNV). As these CNV regions often overlap coding regions of the genome, large lists of potentially copy number polymorphic genes have been produced that are candidates for disease association. Most of the current data regarding normal genic variation, however, has been generated using BAC or SNP microarrays, which lack precision especially with respect to exons. To address this, we assessed 2,790 candidate CNV genes defined from available studies in nine well-characterized HapMap individuals by designing a customized oligonucleotide microarray targeted specifically to exons. Using exon array comparative genomic hybridization (aCGH), we detected 255 (9%) of the candidates as true CNVs including 134 with evidence of variation over the entire gene. Individuals differed in copy number from the control by an average of 100 gene loci. Both partial- and whole-gene CNVs were strongly associated with segmental duplications (55 and 71%, respectively) as well as regions of positive selection. We confirmed 37% of the whole-gene CNVs using the fosmid end sequence pair (ESP) structural variation map for these same individuals. If we modify the end sequence pair mapping strategy to include low-sequence identity ESPs (98-99.5%) and ESPs with an everted orientation, we can capture 82% of the missed genes leading to more complete ascertainment of structural variation within duplicated genes. Our results indicate that segmental duplications are the source of the majority of full-length copy number polymorphic genes, most of the variant genes are organized as tandem duplications, and a significant fraction of these genes will represent paralogs with levels of sequence diversity beyond thresholds of allelic variation. In addition, these data provide a targeted set of CNV genes enriched for regions likely to be associated with human phenotypic differences due to copy number changes and present a source of copy number responsive oligonucleotide probes for future association studies.

Sexual risk behavior 6 months post-high school: associations with college attendance, living with a parent, and prior risk behavior

PURPOSE

This study examined sexual risk behavior (SRB) among a community sample of youth in the fall after their senior year of high school. The primary goal was to examine associations between college and residential status and 3 measures of SRB: casual sex, inconsistent condom use, and high-risk sex.

METHOD

Data were from 834 participants in the Raising Healthy Children project who were surveyed annually during high school and in the fall of the post-high school year.

RESULTS

Of the participants, 30% reported inconsistent condom use, 23% reported casual sex, and 11% reported high-risk sex in the fall after high school. Youth in college were less likely than noncollege youth to report SRB. The protective association between college attendance on one hand and casual sex and intermittent condom use on the other was fully explained by high school substance use, risky sex, and academic performance. The protective effect of college attendance on high-risk sex was partly explained by high school predictors. Living with parents at age 18-19 years was not related to SRB.

CONCLUSIONS

Results from this study indicate that the higher prevalence of SRB among noncollege youth is largely a continuation of patterns of higher risk behavior and lower academic performance during high school. College attendance was protective for the most high-risk sex measure. Findings suggest that human immunodeficiency virus and sexually transmitted infection prevention efforts are needed among young adults who are not attending college and among high school students who have earned poor grades, used drugs, or engaged in SRB.

Men's and women's patterns of substance use around pregnancy

BACKGROUND

Little is known about men's patterns of substance use around their partner's pregnancy, despite evidence from studies of pregnant women that men's substance use may reduce women's ability to desist from substance use during pregnancy, increase the probability that women will return to use postpartum, and increase the risk of adverse child outcomes. The purpose of this study was to describe the association between pregnancy or partner's pregnancy and month-by-month patterns of binge drinking, daily smoking, and marijuana use among young men and women.

METHODS

Data were drawn from the Seattle Social Development Project, which included 412 men and 396 women (age 24 yr) from a community sample of individuals who attended elementary school in the northwestern United States. Event history calendars were used to measure month-by-month patterns of binge drinking, daily smoking, marijuana use, and childbirth over a 3-year period from 1996 to 1999.

RESULTS

Births during the calendar period were reported by 131 women and 77 men. Hierarchical generalized linear modeling analyses showed that men's rates of binge drinking and marijuana use were unaffected by their partner's pregnancy. Pregnancy decreased the probability of substance use among women, but use returned to prepregnancy levels within 2 years postpartum.

CONCLUSIONS

Men's substance use was not affected by their partner's pregnancy. Pregnancy decreased the probability of substance use among women, but substantial proportions of women users of cigarettes and marijuana used these substances during pregnancy. Many of the women who desisted from substance use while pregnant returned to use after their child was born.

Claims of alleged medical negligence in refractive surgery: Causes and avoidance

PURPOSE

To identify the issues cited in claims for alleged medical negligence in cases of refractive surgery.

METHODS

One hundred and one cases of alleged medical negligence following refractive surgery were analysed by a single expert witness. Valid features of the statement of claim and issues identified by the expert as being relevant to the outcome were assessed.

RESULTS

Sixty-five percentage of claims included issues of consent. In one third of these cases the Claimant had particular risk factors for which especially careful counselling was warranted. For 29% of claims there were contraindications to surgery. In 24% there was surgical error resulting in a compromised outcome. In 23% there was avoidable delay in instituting medical management for post-operative complications. Four percentage of cases were precipitated by a second opinion where the clinician giving the opinion was not fully conversant with the facts.

CONCLUSIONS

The number of claims could be substantially reduced by: (1) Instituting proper policies for consent with full documentation throughout the process; (2) Ensuring that surgeons are adequately trained in evaluating pre-operative tests and allowing surgeons adequate time to assess patients prior to surgery; (3) Moderating the case-load for surgery; (4) Ensuring that patients have easy access to medical care post-operatively; (5) Keeping comprehensive and accurate records.

Linking Substance Use and Problem Behavior Across Three Generations

This study examined patterns of between-generation continuity in substance use from generation 1 (G1) parents to generation 2 (G2) adolescents and from G2 adult substance use and G1 substance use to generation 3 (G3) problem behavior in childhood. Structural equation modeling of prospective, longitudinal data from 808 participants, their parents, and their children showed low levels of G1 to G2 cross-generational continuity in the general tendency to use drugs. This effect was fully mediated by G2 early adolescent behavior problems. Drug-specific residual effects were observed across generations for cigarette smoking. Once established in adolescence, substance use in G2 showed stability over time. G2 substance use at age 27 significantly predicted G3 problem behavior. G1 substance use also was related to G3 problem behavior indirectly. These findings highlight the importance of interrupting intergenerational cycles of substance use and problem behavior.

Pathways to Adolescent Substance Use Among Sexually Abused Girls

This study examined the link between childhood sexual abuse and adolescent substance use among girls, and evaluated depressive self-concept and behavioral under-control (BUC) as pathways to substance use for sexually abused girls. Participants (n = 150) were drawn from a longitudinal study of the impact of domestic violence on the lives of women and children. Structural equation modeling revealed that girls' childhood sexual abuse was associated prospectively with their later substance use. This relationship persisted when age, co-occurring forms of child abuse (physical, exposure to domestic violence), childhood depression and aggression, family income, maternal substance use, and parenting practices were controlled. Behavioral under-control mediated the relationship between childhood sexual abuse and later substance use, but depressive self-concept did not. Implications, limitations, and directions for future research are discussed.

Using a pericentromeric interspersed repeat to recapitulate the phylogeny and expansion of human centromeric segmental duplications

Despite considerable advances in sequencing of the human genome over the past few years, the organization and evolution of human pericentromeric regions have been difficult to resolve. This is due, in part, to the presence of large, complex blocks of duplicated genomic sequence at the boundary between centromeric satellite and unique euchromatic DNA. Here, we report the identification and characterization of an approximately 49-kb repeat sequence that exists in more than 40 copies within the human genome. This repeat is specific to highly duplicated pericentromeric regions with multiple copies distributed in an interspersed fashion among a subset of human chromosomes. Using this interspersed repeat (termed PIR4) as a marker of pericentromeric DNA, we recovered and sequence-tagged 3 Mb of pericentromeric DNA from a variety of human chromosomes as well as nonhuman primate genomes. A global evolutionary reconstruction of the dispersal of PIR4 sequence and analysis of flanking sequence supports a model in which pericentromeric duplications initiated before the separation of the great ape species (>12 MYA). Further, analyses of this duplication and associated flanking duplications narrow the major burst of pericentromeric duplication activity to a time just before the divergence of the African great ape and human species (5 to 7 MYA). These recent duplication exchange events substantially restructured the pericentromeric regions of hominoid chromosomes and created an architecture where large blocks of sequence are shared among nonhomologous chromosomes. This report provides the first global view of the series of historical events that have reshaped human pericentromeric regions over recent evolutionary time.

Bovine spongiform encephalopathy

Early epidemiological studies identified bovine spongiform encephalopathy as a feed-borne infection associated with infected meat-and-bone meal in animal feed. The infection may have derived from scrapie in sheep, a spontaneous genetic mutation in cattle, or a transmissible spongiform encephalopathy in another mammalian species. Experimental work on the risk of transmission has necessarily tried to identify risk materials and their infectivity levels, the nature and size of species barriers, the infectious dose, the route of infection, the strain of the agent and the genotype of the animals at risk. The identification of levels of infection in cattle tissues has aided the removal of risk materials from the human and animal food chains. Maternally associated transmission is unlikely to maintain an outbreak, but the offspring of clinical cases appear to be at greater risk when the rate of food-borne exposure is high. Studies of embryo transfer have not shown infection to be transmitted by this means. While the control measures appeared to be straightforward, compliance has at times proved difficult to enforce and quantify. This has necessitated more extensive prohibitions, aggressive enforcement and thorough auditing of compliance levels.

Positive selection of a gene family during the emergence of humans and African apes

Gene duplication followed by adaptive evolution is one of the primary forces for the emergence of new gene function. Here we describe the recent proliferation, transposition and selection of a 20-kilobase (kb) duplicated segment throughout 15 Mb of the short arm of human chromosome 16. The dispersal of this segment was accompanied by considerable variation in chromosomal-map location and copy number among hominoid species. In humans, we identified a gene family (morpheus) within the duplicated segment. Comparison of putative protein-encoding exons revealed the most extreme case of positive selection among hominoids. The major episode of enhanced amino-acid replacement occurred after the separation of human and great-ape lineages from the orangutan. Positive selection continued to alter amino-acid composition after the divergence of human and chimpanzee lineages. The rapidity and bias for amino-acid-altering nucleotide changes suggest adaptive evolution of the morpheus gene family during the emergence of humans and African apes. Moreover, some genes emerge and evolve very rapidly, generating copies that bear little similarity to their ancestral precursors. Consequently, a small fraction of human genes may not possess discernible orthologues within the genomes of model organisms.

Lessons from the human genome: transitions between euchromatin and heterochromatin

The publication of the human genome draft sequence provides, for the first time, a global view of the structural properties of the human genome. Initial sequence analysis, in combination with previous published reports, reveals that more than half of the transition regions between euchromatin and centromeric heterochromatin contain duplicated segments. The individual duplications originate from diverse euchromatic regions of the human genome, often containing intron-exon structure of known genes. Multiple duplicons are concatenated together to form larger blocks of wall-to-wall duplications. For a single chromosome, these paralogous segments can span >1 Mb of sequence and define a buffer zone between unique sequence and tandemly repeated satellite sequences. Unusual pericentromeric interspersed repeat elements have been identified at the junctions of many of these duplications. Phylogenetic and comparative studies of pericentromeric sequences suggest that this peculiar genome organization has emerged within the last 30 million years of human evolution and is a source of considerable genomic variation between closely related primate species. Interestingly, not all human pericentromeric regions show this proclivity to duplicate and transpose genomic sequence, suggesting at least two different models for the organization of these regions.

Segmental duplications: organization and impact within the current human genome project assembly

Segmental duplications play fundamental roles in both genomic disease and gene evolution. To understand their organization within the human genome, we have developed the computational tools and methods necessary to detect identity between long stretches of genomic sequence despite the presence of high copy repeats and large insertion-deletions. Here we present our analysis of the most recent genome assembly (January 2001) in which we focus on the global organization of these segments and the role they play in the whole-genome assembly process. Initially, we considered only large recent duplication events that fell well-below levels of draft sequencing error (alignments 90%-98% similar and > or =1 kb in length). Duplications (90%-98%; > or =1 kb) comprise 3.6% of all human sequence. These duplications show clustering and up to 10-fold enrichment within pericentromeric and subtelomeric regions. In terms of assembly, duplicated sequences were found to be over-represented in unordered and unassigned contigs indicating that duplicated sequences are difficult to assign to their proper position. To assess coverage of these regions within the genome, we selected BACs containing interchromosomal duplications and characterized their duplication pattern by FISH. Only 47% (106/224) of chromosomes positive by FISH had a corresponding chromosomal position by comparison. We present data that indicate that this is attributable to misassembly, misassignment, and/or decreased sequencing coverage within duplicated regions. Surprisingly, if we consider putative duplications >98% identity, we identify 10.6% (286 Mb) of the current assembly as paralogous. The majority of these alignments, we believe, represent unmerged overlaps within unique regions. Taken together the above data indicate that segmental duplications represent a significant impediment to accurate human genome assembly, requiring the development of specialized techniques to finish these exceptional regions of the genome. The identification and characterization of these highly duplicated regions represents an important step in the complete sequencing of a human reference genome.

Prevalence and familial aggregation of schistosomal liver morbidity in Kenya: evaluation by new ultrasound criteria

Severe periportal fibrosis is not an inevitable consequence of infection with Schistosoma mansoni. Genetic predisposition may be a deciding factor in the development of disease. To assess the contribution of genetic factors in the severity of hepatic fibrosis, the degree of familial aggregation was determined in a Kenyan population. Schistosomal fibrosis was identified with hepatic ultrasound and newly proposed World Health Organization criteria, which include both qualitative and quantitative observations. These 2 aspects of the criteria correlated well with one another. The peak prevalence of ultrasound proven fibrosis trailed 5-10 years behind peak prevalence of infection and declined sharply after age 50 years. This pattern was consistent with either resolution of severe fibrosis over 10-20 years or early death of those severely affected. Genetic predisposition appears to be a weak factor in the development of severe disease in this population, since no household or familial aggregation could be identified.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Circular polarisation in star-forming regions: possible implications for homochirality

Our discovery of high degrees of circular polarisation in some star-forming regions provides an attractive mechanism for the origin of homochirality. The largest degrees of circular polarisation, so far observed at near-infrared wavelengths, are thought to arise from the scattering of stellar radiation from aligned dust grains and are calculated to extend down to UV wavelengths. The extent of the region where circularly polarised light (CPL) of a single handedness originates is very large, and it is likely that the whole of a planetary system would see a single handedness of CPL also. We present the observational data, models of the scattering that leads to the production of CPL, and a model for the origin of homochirality. We also discuss briefly future laboratory and space-based experiments.

A GAL4-like protein is involved in the switch between biotrophic and necrotrophic phases of the infection process of Colletotrichum lindemuthianum on common bean

Random insertional mutagenesis was conducted with the hemibiotrophic fungus Colletotrichum lindemuthianum, causal agent of common bean anthracnose. Nine mutants that were altered in their infection process on the host plant were generated. One of these, H433 is a nonpathogenic mutant able to induce necrotic spots on infected leaves rapidly. These spots are similar to those observed during the hypersensitive reaction. Cytological observations showed that the development of the mutant H433 is stopped at the switch between the biotrophic and the necrotrophic phases. This mutant carries two independent insertions of the transforming plasmid pAN7-1. Complementation studies using the wild-type genomic regions corresponding to the two insertions showed that one is responsible for the H433 phenotype. Sequencing analysis identified a single open reading frame that encoded a putative transcriptional activator belonging to the fungal zinc cluster (Zn[II](2)Cys(6)) family. The corresponding gene was designated CLTA1 (for C. lindemuthianum transcriptional activator 1). Expression studies showed that CLTA1 is expressed in low amounts during in vitro culture. Targeted disrupted strains were generated, and they exhibited the same phenotype as the original mutant H433. Complementation of these disrupted strains by the CLTA1 gene led to full restoration of pathogenicity. This study demonstrates that CLTA1 is both a pathogenicity gene and a regulatory gene involved in the switch between biotrophy and necrotrophy of the infection process of a hemibiotrophic fungus.

Patterns of meiotic recombination on the long arm of human chromosome 21

In this study we quantify the features of meiotic recombination on the long arm of human chromosome 21. We constructed a 67. 3-centimorgan (cM) high-resolution, comprehensive, and accurate genetic linkage map of chromosome 21q using 187 highly polymorphic markers covering almost the entire long arm; 46 loci, consisting of mutually recombining marker sets, were ordered with greater than 1000:1 odds and with average interlocus distance of 1.46 cM. These markers were used to accurately identify all exchanges in 186 female and 160 male meioses and to show (1) significant excess of recombination in female versus male meioses, (2) an overall decline in female:male recombination between the centromere and the telomere, (3) greater positive chiasma interference in male than in female meioses, and (4) lack of correlation between exchange frequency and parental age. By comparing the genetic map with the 21q sequence map, we show a general trend of increasing male, but near-constant female, recombination versus physical distance across 21q, explaining the gender-specific recombination effect. The recombination rate varies considerably between genders across 21q but is the greatest (eightfold) in the pericentromeric region, with a rate of approximately 250 kb/cM in females and approximately 2125 kb/cM in males. We used information on the locations of all exchanges to construct an empirical map function that confirms the statistical findings of positive interference. These analyses reveal that occurrence of recombination on 21q is not only gender-specific but also region-specific and that recombination suppression at the centromere is not universal. We also find evidence that male exchange location is highly correlated with gene density.