Rapid disappearance of a warm, dusty circumstellar disk.

Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation that can account for the variety of planetary systems discovered so far. The formation of Earth-like planets through collisional accumulation of rocky objects within a disk has mainly been explored in theoretical and computational work in which post-collision ejecta evolution typically is ignored, although recent work has considered the fate of such material. Here we report observations of a young, Sun-like star (TYC 8241 2652 1) where infrared flux from post-collisional ejecta has decreased drastically, by a factor of about 30, over a period of less than two years. The star seems to have gone from hosting substantial quantities of dusty ejecta, in a region analogous to where the rocky planets orbit in the Solar System, to retaining at most a meagre amount of cooler dust. Such a phase of rapid ejecta evolution has not been previously predicted or observed, and no currently available physical model satisfactorily explains the observations.

Images of a fourth planet orbiting HR 8799.

High-contrast near-infrared imaging of the nearby star HR 8799 has shown three giant planets. Such images were possible because of the wide orbits (>25 astronomical units, where 1 au is the Earth-Sun distance) and youth (<100 Myr) of the imaged planets, which are still hot and bright as they radiate away gravitational energy acquired during their formation. An important area of contention in the exoplanet community is whether outer planets (>10 au) more massive than Jupiter form by way of one-step gravitational instabilities or, rather, through a two-step process involving accretion of a core followed by accumulation of a massive outer envelope composed primarily of hydrogen and helium. Here we report the presence of a fourth planet, interior to and of about the same mass as the other three. The system, with this additional planet, represents a challenge for current planet formation models as none of them can explain the in situ formation of all four planets. With its four young giant planets and known cold/warm debris belts, the HR 8799 planetary system is a unique laboratory in which to study the formation and evolution of giant planets at wide (>10 au) separations.

Extreme collisions between planetesimals as the origin of warm dust around a Sun-like star.

The slow but persistent collisions between asteroids in our Solar System generate a tenuous cloud of dust known as the zodiacal light (because of the light the dust reflects). In the young Solar System, such collisions were more common and the dust production rate should have been many times larger. Yet copious dust in the zodiacal region around stars much younger than the Sun has rarely been found. Dust is known to orbit around several hundred main-sequence stars, but this dust is cold and comes from a Kuiper-belt analogous region out beyond the orbit of Neptune. Despite many searches, only a few main-sequence stars reveal warm (> 120 K) dust analogous to zodiacal dust near the Earth. Signs of planet formation (in the form of collisions between bodies) in the regions of stars corresponding to the orbits of the terrestrial planets in our Solar System have therefore been elusive. Here we report an exceptionally large amount of warm, small, silicate dust particles around the solar-type star BD+20,307 (HIP 8920, SAO 75016). The composition and quantity of dust could be explained by recent frequent or huge collisions between asteroids or other 'planetesimals' whose orbits are being perturbed by a nearby planet.

X-ray and molecular emission from the nearest region of recent star formation.

The isolated, young, sunlike star TW Hya and four other young stars in its vicinity are strong x-ray sources. Their similar x-ray and optical properties indicate that the stars make up a physical association that is on the order of 20 million years old and that lies between about 40 and 60 parsecs (between about 130 and 200 light years) from Earth. TW Hya itself displays circumstellar CO, HCN, CN, and HCO+ emission. These molecules probably orbit the star in a solar-system-sized disk viewed more or less face-on, whereas the star is likely viewed pole-on. Being at least three times closer to Earth than any well-studied region of star formation, the TW Hya Association serves as a test-bed for the study of x-ray emission from young stars and the formation of planetary systems around sunlike stars.

Myonecrosis after revascularization procedures.

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating > 10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.

Studies on ageing in Turbatrix aceti.

Morphologic and physiologic changes which occur during senescence in the free-living nematode Turbatrix aceti are described. With age areas of the interchordal hypodermis containing nerve elements thickened, electron-dense aggregates formed within the pseudocoelom and age pigment granules accumulated within the intestinal epithelium. Specific gravity did not change with age. Old nematodes which had reproduced showed increased osmotic fragility, but this change was not observed in virgin females. The parameters characterizing senescence in T. aceti are compared with those of Caenorhabditis briggsae, another nematode being used as a model to study biological ageing.

Television's impact on children.

Television has a major impact on children's knowledge, attitudes, and behavior. Research has demonstrated the association between television viewing and four areas: (1) children's aggressive behavior; (2) racial and sex-role stereotypes; (3) decreased interest in reading and school activities; and (4) poorer health habits and attitudes. Methodological limitations make it difficult to draw firm conclusions about a causal relationship between television viewing and children's behavior. Representative studies in these four areas are reviewed, important methodological concerns are pointed out, and conclusions from the research findings are drawn. The implications of the data for pediatricians and other health professionals are discussed.

Maternal depression: a concern for pediatricians.

Maternal depression is common in clinical experience but has not been fully addressed in the pediatric literature. Depression can refer to either depressive symptoms or a diagnosable depression. Depression among mothers occurs frequently, is persistent, and is related to other factors such as low social class and marital disharmony. Studies demonstrate an association between a mother's depression and adverse outcomes for her child including low birth weight, behavior problems, somatic complaints, poor growth, accidents, and affective illness. Affect and child-rearing characteristics of depressed mothers seem to be important factors in mediating these poor outcomes. Pediatricians have a special role in helping depressed mothers and their children.

Sleep problems in early childhood: continuities, predictive factors, and behavioral correlates.

A longitudinal study, based on interviews with 308 middle-class, preponderantly white mothers, provided an opportunity to evaluate the continuity, predictive factors, and behavioral correlates of sleep problems in young children. When their children were 8 months old, 10% of the mothers reported that their babies woke three or more times per night, 8% reported that the babies took an hour or more to settle after waking, 5% complained that their own sleep was severely disrupted by the child, and 18% reported at least one of these problems. At 3 years of age, 29% of the children had difficulty getting to bed and/or falling asleep or staying asleep. Of children with a sleep problem at 8 months of age, 41% still had a problem at 3 years of age, whereas only 26% of children without a problem at 8 months of age had a problem at 3 years of age (P less than .001). Among children with sleep problems at 8 months of age, mothers' depressed feelings were the only measured demographic or psychosocial factor associated with persistent sleep problems (P = .02). A separate analysis indicated that these depressed feelings did not appear to be a consequence of the child's sleep problem. Future studies should evaluate how maternal depression interacts with other factors to result in persistent sleep problems. Children with persistent sleep problems were more likely to have behavior problems, especially tantrums (P less than .02) and behavior management problems (P less than .01), than were children without persistent sleep problems (P less than .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Stomachaches and headaches in a community sample of preschool children.

The epidemiology of recurrent stomachache and headache was studied in a community sample of 308 preschool children, most of whom were white. When the children were 3 years old, interviews with their mothers indicated that 3% had recurrent headaches and 9% had recurrent stomachaches. Children with recurrent stomachaches were more likely than those without recurrent stomachaches to have mothers who were emotionally depressed (P less than .01), had marital problems (P less than .05), and perceived their own health as poor (P less than .05). When maternal poor health was controlled, depression was still associated with their children having stomachaches (P less than .05). Prospectively collected data demonstrate that children with recurrent stomachaches did not have bowel difficulties when they were infants. Other psychosocial stresses and demographic factors were not associated with stomachaches. The only variable associated with recurrent headache was maternal depression. Children with recurrent headaches or stomachaches were more likely to have behavior problems, as measured by the Behavior Screening Questionnaire, than were children without these symptoms. The analysis presents new data on these common symptoms of childhood.

Drug use among adolescent mothers: profile of risk.

Adolescent pregnancy and adolescent drug use are important clinical and public health problems. Yet, few studies have systematically investigated the patterns of substance use among pregnant and parenting adolescents. Because adverse outcomes are not found uniformly for all adolescent mothers, use of illicit drugs may be a key factor in determining which mothers and their infants will have poor outcomes. In this study, the patterns of drug use are described and differences in the demographic and psychosocial profile among 253 pregnant adolescents are investigated. Results obtained from interviews and urine assay for marijuana and cocaine indicate that lifetime use was 84% for alcohol, 62% for marijuana, and 23% for cocaine, whereas use in the past year was 40% for marijuana and 17% for cocaine. Compared with nonusers, pregnant adolescent drug users were more likely to be North American black, have a history of elective abortion and venereal disease, report more negative life events and violence during pregnancy, and receive more support from the father of the baby who was more likely to use marijuana and cocaine (P less than .01). Furthermore, according to logistic regression analysis results after controlling for age and ethnicity, adolescents who used illicit substances in the past year were three times more likely to have a male partner who used marijuana or cocaine and were two times more likely to have a history of venereal disease compared with nonusers. The findings suggest that drug use, whether as a mechanism or a marker, is associated with social and medical characteristics that are likely to contribute to negative outcomes among adolescent mothers and their infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating catecholamine concentrations in cocaine-exposed neonates: a pilot study.

Twenty newborns, 12 with prenatal exposure to cocaine and an unexposed control group of 8, were studied to determine concentrations of circulating catecholamines and their relationship to newborn behavior. Birth weight of the cocaine-exposed neonates was significantly lower than that of the control group. Gestational age, length, and head circumference of the cocaine-exposed neonates were also lower, although the differences did not reach statistical significance. Between 24 and 48 hours of age, circulating concentrations of norepinephrine, dopamine, and the catecholamine precursor dihydroxyphenylalanine were measured and behavior was assessed using the Neonatal Behavioral Assessment Scale. Mean dihydroxyphenylalanine concentrations were increased in the cocaine-exposed newborns (10.3 ng/mL vs 5.9 ng/mL, P = .055), while there was no difference between the groups in mean norepinephrine or dopamine concentrations. There was a significant negative correlation between norepinephrine concentration and orientation cluster score for the cocaine-exposed newborns (r2 = .6979, P = .005). norepinephrine concentration did not correlate with the score for any other behavioral cluster, nor did dopamine or dihydroxyphenylalanine concentration correlate with the score for any cluster. These preliminary data from a pilot study suggest that catecholamine activity is increased in cocaine-exposed newborns and may play a role in neurobehavioral disturbances associated with prenatal exposure to this drug.

Night waking during infancy: role of parental presence at bedtime.

Night waking occurs commonly in infants and young children. The goal of this study is to determine whether parents who report being present when their infant falls asleep at bedtime are more likely to report increased frequency of night waking by the infant. Mothers were consecutively recruited when they brought their infants to the clinic for their 9-month well-child visit. A total of 122 mothers agreed to participate and completed a questionnaire consisting of closed-ended, forced choice questions about their infant's feeding and sleeping behavior, and demographic and psychosocial characteristics. For 33% of the mothers, a parent was routinely present when the infant went to sleep. The entire sample of infants averaged 4.1 night wakings during the week prior to questionnaire completion. Infants whose parents were present at bedtime were significantly more likely to wake at night than infants whose parents were not present (6.2 vs 3.1, P = .01). Frequent night waking (seven or more wakings in the prior week) occurred in 28% of the sample. More of the infants whose parents were present experienced frequent night waking compared with infants whose parents were not present (40% vs 22%, P less than .04). When potential confounding variables were controlled by multivariate analysis, parents being present when the child went to sleep was independently associated with night waking (P less than .03). The association of parental presence at bedtime and night waking has implications for preventing and managing disruptive night waking in infancy.

Another myth: reduced hospital visiting by inner-city mothers.

Hospitalization of young children produces stress that can be reduced by the presence of a parent. Inner-city parents, however, are generally believed to visit the hospital less often than more affluent parents. At Boston City Hospital pediatric nursing and medical staff (N = 60) were surveyed to obtain their impressions of maternal visiting and its determinants; then 80/94 consecutive admissions of children less than age 5 years were surveyed to record the mothers' actual visiting times. Each mother was interviewed to determine sociodemographic status, her perception of her child's behavior, and her perception about visiting. The staff believed that few mothers (20%) would visit more than 4 h/d, but the study showed that nearly three times this many mothers did visit more than 4 h/d. The median visit length was five hours, and 20% of the mothers roomed-in at least once. Contrary to staff expectations, neither job nor child care responsibilities were related to visit length. Mothers who thought visits helped their children visited longer (10.6 v 5.3 hours, P less than .001). Contrary to staff beliefs, most inner-city mothers successfully overcame external and emotional barriers to visiting their hospitalized children. Staff input and an educational effort might facilitate longer visits by the one third of mothers who did not recognize the importance of their visiting their children.

Reducing night waking in infancy: a primary care intervention.

Approximately 25% of infants wake regularly at night and need help in resettling. The purpose of this study was to implement and evaluate a brief intervention to prevent such night waking. The study used a prospective cohort design with historical controls. Information from the control group was collected at the 9-month visit. The intervention group was enrolled at the 4-month visit. The intervention consisted of information about sleep-onset associations, completion of a sleep chart, and discussion about sleep with the pediatrician. The outcome was also measured at the 9-month visit. To obscure the purpose of the study, the outcome questionnaire for both groups addressed feeding and sleeping. One hundred twenty-eight (74%) of 172 eligible infant-parent pairs comprised the control group and 164 (74%) of 222 the intervention group. The majority of families were white, married, and well-educated. The groups were similar with regard to sociodemographic variables and factors thought to be related to night waking such as current breast-feeding, thumb/pacifier sucking, maternal isolation, and parental perception of difficult child. At 9 months of age, the intervention infants were reported to experience 36% less night waking per week compared with those in the control group (2.5 vs 3.9 wakings per week, P = .02). Frequent night waking was twice as common in control infants (27% vs 14%, P = .01). It is concluded that this pediatric intervention can help parents reduce night waking in infants.

Cerebrospinal fluid monoamine precursors and metabolites in human neonates following in utero cocaine exposure: a preliminary study.

BACKGROUND: Cocaine acts in the central nervous system by increasing dopamine release and inhibiting the reuptake of dopamine and other monoaminergic neurotransmitters. Prenatal cocaine exposure may cause neurochemical changes in developing monoaminergic neurons and might alter brain structure and function. No data have been published on central nervous system monoamine precursors and metabolites in human neonates exposed prenatally to cocaine. METHODS: Cerebrospinal fluid (CSF) was obtained from neonates undergoing lumbar puncture to rule out infection. The CSF was analyzed for the neurotransmitter precursors and metabolites tryptophan, tyrosine, 3-methoxy-4-hydroxyphenylglycol, homovanillic acid, and 5-hydroxyindoleacetic acid. Drug exposure was ascertained by medical record review and urine and meconium assays. RESULTS: Eleven neonates were cocaine-exposed, based on positive meconium or urine assays for benzoylecgonine; 20 were unexposed, based on both negative history and assay. The exposed and unexposed groups did not differ significantly in gender, perinatal stress, clinical illness, or exposure to other illicit drugs, but did differ in mean gestational age, growth parameters, and exposure to cigarettes. Cocaine-exposed neonates had significantly lower levels of CSF homovanillic acid (mean 148.1 vs 218.5 ng/mL, P = .01). The magnitude of this difference was similar after correcting for each of four potential confounding factors, although no longer statistically significant in all cases (P values ranged from .044 to .17). No significant differences were observed for tyrosine, tryptophan, 5-hydroxyindoleacetic acid, or 3-methoxy-4-hydroxyphenylglycol. CONCLUSIONS: These preliminary results suggest an association between prenatal cocaine exposure and decreased CSF homovanillic acid, the principal metabolite of dopamine. Prenatal cocaine exposure may result in changes in central dopaminergic systems in the human neonate.

Restraining orders: a frequent marker of adverse maternal health.

OBJECTIVE: Women with histories of interpersonal violence are poorly identified because of barriers in self-disclosure. This study identified differences on maternal health and child behavior between women who report filing a restraining order (RO) and those who do not among a nonreferred sample of women living in high-crime neighborhoods. METHODS: During a maternal interview mothers were asked whether they ever filed a RO, the victim/defendant relationship, the number of times, and the year of the filing. Four types of violence were coded independently based on maternal narratives: verbal harassment, verbal threats or intimidation, physical assault, and destruction of property. We controlled for differences between RO and non-RO groups regarding demographic background, partner characteristics, other types of maternal past victimization, and use of alcohol and illicit drugs. Outcomes for mothers include partner aggression (Conflict Tactics Scale-R), perception of health and bodily pain (SF-36 Health Survey), distress symptoms (SCL90-R), posttraumatic stress (PTS)-related symptoms, and partial posttraumatic stress disorder (PTSD) diagnosis (modified Diagnostic Interview Schedule PTSD-Module). Outcomes for the child include partner aggression (Conflict Tactic Scale-R), behavior problems (CBC 2-3 or Child Behavior Checklist), and PTS-related symptoms (PTS-related symptom checklist). PATIENTS: One hundred sixty patients between 3.0 to 6.1 years who resided within five residential ZIP codes with a high rate of local crime in the City of Boston were drawn from a pediatric care clinic practice. Patients were participants of a larger study about the impact of community violence on mother-child relations. RESULTS: Sixty-four (40%) of 160 mothers reported a history of filing a RO against a current boyfriend or husband (39%), ex-boyfriend or husband (44%), someone known (8%), or other (9%), with a mean of 3.9 years (standard deviation = 3.5 years) since RO filing. After controlling for covariates of marital status, immigrant status, public assistance, and lifetime sexual victimization, we found a significant multivariate analysis of covariance group effect on maternal outcomes. Analysis of covariance analyses indicated that mothers in the RO group experienced higher current partner verbal aggression and physical violence to mother, poorer health, and higher PTS-related symptoms, compared with mothers in the non-RO group. More mothers in the RO group met partial lifetime PTSD diagnosis. Unadjusted for maternal covariates, the multivariate analysis of variance analyses on child outcomes (partner aggression to child, behavior problems, and PTS-related symptoms) indicated a nonsignificant group effect. CONCLUSIONS: Among dyads residing in high-risk crime areas, the incidence of RO histories is substantive considering this was a nonshelter, nonreferred sample. The inquiry about the history of a RO may provide a new and efficient marker to quality of current partner relationship, maternal health, and maternal stress-related symptomatology.

Late dose-response effects of prenatal cocaine exposure on newborn neurobehavioral performance.

OBJECTIVE: To determine in a representative sample of full-term urban newborns of English-speaking mothers whether an immediate or late dose-response effect could be demonstrated between prenatal cocaine exposure and newborn neurobehavioral performance, controlling for confounding factors. METHODS: The Neonatal Behavioral Assessment Scale (NBAS) was administered by masked examiners to a total sample of 251 clinically healthy, full-term infants at 2 days and/or 17 days. Three in utero cocaine exposure groups were defined: heavily exposed (n = 44, > 75th percentile self-reported days of use during pregnancy and/or > 75th percentile of meconium benzoylecognine concentration); lightly exposed (n = 79, less than both 75th percentiles); and unexposed (n = 101, no positive biological or self-report marker). At the 3-week examination there were 38 heavily exposed, 73 lightly exposed, and 94 unexposed infants. Controlling for infant birth weight, gestational age, infant age at the time of examination, mothers' age, perinatal risk, obstetric medication, and alcohol, marijuana, and cigarette use, a regression analysis evaluated the effects of levels of cocaine exposure on NBAS performance. RESULTS: No neurobehavioral effects of exposure on the newborn NBAS cluster scores or on the qualifier scores were found when confounders were controlled for at 2 to 3 days of age. At 3 weeks, after controlling for covariates, a significant dose effect was observed, with heavily exposed infants showing poorer state regulation and greater excitability. CONCLUSIONS: These findings demonstrate specific dose-related effects of cocaine on 3-week neurobehavioral performance, particularly for the regulation of arousal, which was not observed in the first few days of life.

Neonatal outcome: is adolescent pregnancy a risk factor?

It has been widely reported that adolescent mothers are more likely to experience poor pregnancy outcome, especially low-birth-weight and/or premature infants. Recent data suggest that this poor outcome may be attributed to confounding health and social characteristics of adolescent mothers. A study of maternal health and neonatal development at Boston City Hospital provided an opportunity to assess whether adolescent mothers deliver infants with poorer outcomes at birth than nonadolescents independent of numerous social and health differences between adolescent and nonadolescent mothers. A total of 275 infants of primiparous adolescents (aged 13 to 18 years) were compared at birth with 423 infants of primiparous nonadolescents. Size at birth, length of gestation, Apgar scores, and birth trauma were examined. The only statistically significant difference between the two groups was that adolescent mothers delivered infants whose mean weight was 94 g less (P less than .03) than infants of nonadolescent mothers. Multiple and logistic regression analyses demonstrated that several health and social factors, but not adolescent status, were independently associated with the measures of adverse infant outcome. A subsequent regression analysis demonstrated similarly that being a younger adolescent (16 years and younger) did not independently predict low birth weight at delivery or other measured adverse neonatal outcomes. These data support the view that health and social factors are more important to poor fetal outcome among primiparous mothers than adolescent status. Some of the health factors are amenable to clinical intervention.

Impact of maternal work outside the home during pregnancy on neonatal outcome.

The impact of mothers' work during pregnancy upon neonatal outcome has not been fully elucidated. A study of maternal health habits and neonatal outcome conducted from 1977 to 1979 at Boston City Hospital assessed the effects of paid work outside the home during pregnancy, particularly third trimester work in a standing position, upon duration of gestation and intrauterine growth, while controlling for potentially confounding variables. Postpartum, 1,690 low-income women were interviewed to provide detailed information on their sociodemographic and health characteristics. Of the 1,507 women whose work status during pregnancy could be classified, 55% did not perform paid work outside the home or attend school, 7% worked into the third trimester in a standing position, and 38% had other work histories or attended school. Infants were examined according to a standard protocol by pediatricians blind to mothers' work history. There was no significant relationship between the mothers' work history during pregnancy and the infants' length of gestation, weight, or head circumference at birth, when confounding variables were controlled statistically by multiple regression analyses. However, women who worked in a standing position into the third trimester delivered infants who were longer than infants born either to mothers with other work histories or to mothers who did not work or attend school. Healthy women with uncomplicated low-risk pregnancies who feel well enough to attend school or work during pregnancy, even in a job requiring some standing, may do so without fear that their infant will suffer shortened gestation or impaired intrauterine growth.