Microscopic description of the low-temperature anomalies in silica and lithium silicate via computer simulations.

Information about the nature of the low-temperature anomalies and in particular the properties of the tunneling systems in silica and lithium silica glasses are revealed via computer simulations. The potential energy landscape of these systems is systematically explored for adjacent pairs of local minima which may act as double-well potentials (DWPs) at low temperatures. Three different types of DWPs are distinguished, related to perfectly coordinated silica, intrinsic silica defects, and extrinsic defects. Their properties such as the spatial extension and the dipole moment are characterized in detail. Furthermore, the absolute number of tunneling systems, that is, symmetric DWPs, is estimated. The results are compared with dielectric echo, specific heat, and acoustic experiments on Suprasil I and Suprasil W. A semiquantitative agreement for all relevant features is obtained.

Height, weight and body mass index in early adulthood and risk of schizophrenia.

OBJECTIVE: To illuminate the possible associations between height, weight, and body mass index (BMI) during early adulthood and the development of schizophrenia. METHOD: This prospective study is based on an all-male sample of 3210 individuals from the Copenhagen Perinatal Cohort, comprising individuals born between 1959 and 1961. In 1999, cases of schizophrenia were identified in the Danish Psychiatric Central Register, and the cases were compared with the cohort pool of controls with respect to height, weight, and BMI from draft records. The effect of low BMI was adjusted for parental social status when the cohort members were 1 year old, birth weight, birth length, and maternal pre-pregnancy BMI. RESULTS: Forty-five cases of schizophrenia had a lower young adult mean body weight and BMI than controls. A significant inverse relationship between BMI and risk of later schizophrenia was found. For each unit increase in BMI, the adjusted odds ratio was 0.81 (95% CI, 0.70-0.93) and the risk of schizophrenia decreased by 19%. Excluding individuals who had been admitted to an in-patient facility before or within 5 years after appearing before the draft board, yielded virtually the same results. No significant differences between cases and controls were observed with respect to adult height. CONCLUSION: Independent of several possible confounders, an inverse relationship between young adult BMI and risk of later development of schizophrenia was demonstrated in this all-male sample.

What is moving in silica at 1 K? A computer study of the low-temperature anomalies.

Though the existence of two-level systems (TLS) is widely accepted to explain low-temperature anomalies in many physical observables, knowledge about their properties is very rare. For silica, which is one of the prototype glass-forming systems, we elucidate the properties of the TLS via computer simulations by applying a systematic search algorithm. We get specific information in the configuration space, i.e., about relevant energy scales, the absolute number of TLS, and electric dipole moments. Furthermore, important insight about the real-space realization of the TLS can be obtained. Comparison with experimental observations is included.

Breastfeeding and risk of schizophrenia in the Copenhagen Perinatal Cohort.

OBJECTIVE: The aim was to study whether early weaning from breastfeeding may be associated with increased risk of schizophrenia. METHOD: The current sample comprises 6841 individuals from the Copenhagen Perinatal Cohort of whom 1671 (24%) had been breastfed for 2 weeks or less (early weaning) and 5170 (76%) had been breastfed longer. Maternal schizophrenia, parental social status, single mother status and gender were included as covariates in a multiple regression analysis of the effect of early weaning on the risk of hospitalization with schizophrenia. RESULTS: The sample comprised 93 cases of schizophrenia (1.4%). Maternal schizophrenia was the strongest risk factor and a significant association between single mother status and elevated offspring risk of schizophrenia was also observed. Early weaning was significantly related to later schizophrenia in both unadjusted and adjusted analyses (adjusted odds ratio 1.73 with 95% CI: 1.13-2.67). CONCLUSION: No or <2 weeks of breastfeeding was associated with elevated risk of schizophrenia. The hypothesis of some protective effect of breastfeeding against the risk of later schizophrenia is supported by our data.

Origin of the fragile-to-strong crossover in liquid silica as expressed by its potential-energy landscape.

The origin of the fragile-to-strong crossover in liquid silica is characterized in terms of properties of the potential-energy landscape (PEL). Using the standard BKS model [B. W. H. van Beest, G. J. Kramer, and R. A. van Santen, Phys. Rev. Lett. 64, 1955 (1990)] of silica we observe a low-energy cutoff of the PEL. It is shown that this feature of the PEL is responsible for the occurrence of the fragile-to-strong crossover and may also explain the avoidance of the Kauzmann paradox. The number of defects, i.e., deviations from the ideal tetrahedral structure, vanishes for configurations with energies close to this cutoff. This suggests a structural reason for this cutoff.

Better psychological functioning and higher social status may largely explain the apparent health benefits of wine: a study of wine and beer drinking in young Danish adults.

BACKGROUND: Findings from a recent series of Danish studies suggest that moderate wine drinkers are healthier than those who drink other alcoholic beverages or those who abstain. OBJECTIVE: To identify possible explanatory factors associated with the health benefits of wine consumption through the examination of a wide spectrum of social, cognitive, and personality characteristics related to both beverage choice and health in young Danish adults. SUBJECTS AND METHODS: Descriptive cross-sectional study of characteristics associated with beverage choice in a sample of 363 men and 330 women between the ages of 29 and 34 years, selected from the Copenhagen Perinatal Cohort on the basis of perinatal records. MAIN OUTCOME MEASURES: Socioeconomic status, education, IQ, personality, psychiatric symptoms, and health-related behaviors, including alcohol consumption, were analyzed. The outcome variables were subjected to linear and logistic regression analyses with 2 factors (beer and wine), each with 2 levels (drinking or not drinking a certain beverage type). RESULTS: Wine drinking was significantly associated with higher IQ, higher parental educational level, and higher socioeconomic status. Beer drinking was significantly associated with lower scores on the same variables. On scales concerning personality, psychiatric symptoms, and health-related behaviors, wine drinking was associated with optimal functioning and beer drinking with suboptimal functioning. CONCLUSIONS: Our data demonstrate that wine drinking is a general indicator of optimal social, cognitive, and personality development in Denmark. Similar social, cognitive, and personality factors have also been associated with better health in many populations. Consequently, the association between drinking habits and social and psychological characteristics, in large part, may explain the apparent health benefits of wine.

Maternal lung adenocarcinoma metastatic to the scalp of a fetus. Case report.

Maternal malignancy metastatic to the fetus is a rare event, with most neoplasms being either melanocytic or hematopoietic in origin. This report is the first known case of a maternal lung adenocarcinoma metastatic to a fetus. At 2 months of age, this male infant developed multiple scalp masses that were locally resected but rapidly recurred. The histology of the scalp lesions and that of a biopsy of the mother's tumor were both adenocarcinoma and were remarkably similar in appearance. In situ hybridization of tumor cells from this male infant found many large nuclei with XX signals indicating that the tumor was of maternal origin. This patient is alive, well and free of malignancy 5 years after a wide local resection of the scalp and skin grafting.

Deep venous thrombosis and pulmonary embolus after face lift: a study of incidence and prophylaxis.

Deep venous thrombosis and pulmonary embolus are known risks of surgery. However, the incidence of these conditions in face lift is unknown. In this study, the incidence of deep venous thrombosis/pulmonary embolus after face lift is studied and factors associated with thromboembolic complications are evaluated. One-third of the active members of the American Society for Aesthetic Plastic Surgery were randomly selected. Participating surgeons completed a one-page survey providing information on face-lift procedures during a 12-month study period. A response rate of 80 percent was achieved, with 273 of the 342 surgeons responding to the survey. A total of 9937 face-lift procedures were reported in the 1-year study period. There were 35 patients with deep venous thrombosis (0.35 percent), 14 patients with pulmonary embolus (0.14 percent), and 1 patient death in the series. Although 43.5 percent of patients underwent face lift under general anesthesia, 83.7 percent of deep venous thrombosis/pulmonary embolus events occurred with general anesthesia. For prophylaxis for deep venous thrombosis/pulmonary embolus, 19.7 percent of the surgeons used intermittent compression devices, 19.6 percent used thromboembolic disease hose or Ace wraps, and 60.7 percent used no prophylaxis. Of patients developing deep venous thrombosis/pulmonary embolus, 4.1 percent were treated prophylactically with intermittent compression devices, 36.7 percent with thromboembolic disease hose/Ace wraps, and 59.2 percent with no prophylaxis. It was found that deep venous thrombosis/pulmonary embolus after face lift is a measurable complication experienced by one of nine surgeons surveyed. Deep venous thrombosis/pulmonary embolus is more likely to occur when the procedure is performed under general anesthesia. The majority of plastic surgeons surveyed used no prophylaxis for deep venous thrombosis when performing face-lift procedures. Intermittent compression devices were associated with significantly fewer thromboembolic complications, whereas Ace wrap/thromboembolic disease hose afforded no protection against deep venous thrombosis/pulmonary embolus when used alone. In conclusion, aesthetic surgeons should consider adopting intermittent compression devices when performing face lift under general anesthesia.

In vitro characteristics of neonatal hemangioma endothelial cells: similarities and differences between normal neonatal and fetal endothelial cells.

BACKGROUND: Increased angiogenesis and eventual involution are major characteristics of neonatal hemangiomas. The mechanism to explain this transition is not completely understood. METHODS: To determine the nature of these changes, endothelial cells were isolated from eight hemangiomas and the growth characteristics and morphology of these cells were compared to cells isolated from normal fetal and neonatal skin. Three cells lines were further characterized by analyzing protein expression with immunohistochemistry and FACS analysis. RESULTS: Hemangioma endothelial cells converted to a spindle-shaped morphology similar to that of fetal endothelial cells whereas neonatal endothelial cells maintained their characteristic epithelioid morphology. While neonatal, hemangioma and fetal endothelial cells continued to express platelet-endothelial cell adhesion molecule-1 (PECAM-1) and von Willebrand factor (vWf), hemangioma and fetal cells expressed both proteins at a lower level and in a distribution distinct from normal neonatal endothelial cells. Neonatal endothelial cells continued to express epithelial specific Type IV collagen, while hemangioma and fetal endothelial cells produced interstitial Type I collagen. CONCLUSIONS: Both cell morphology and protein expression of neonatal hemangioma endothelial cells were more characteristic of embryonic microvascular endothelial cells than that of postembryonic cells demonstrating a similarity in these two cell types and suggesting a dysfunction in the normal growth and maturation of endothelial cells in this tumor.

Would you say you "had sex" if...?

CONTEXT: The current public debate regarding whether oral sex constitutes having "had sex" or sexual relations has reflected a lack of empirical data on how Americans as a population define these terms. OBJECTIVE: To determine which interactions individuals would consider as having "had sex." METHODS: A question was included in a survey conducted in 1991 that explored sexual behaviors and attitudes among a random stratified sample of 599 students representative of the undergraduate population of a state university in the Midwest. PARTICIPANTS: The participants originated from 29 states, including all 4 US Census Bureau geographic regions. Approximately 79% classified themselves as politically moderate to conservative. MAIN OUTCOME MEASURE: Percentage of respondents who believed the interaction described constituted having "had sex." RESULTS: Individual attitudes varied regarding behaviors defined as having "had sex": 59% (95% confidence interval, 54%-63%) of respondents indicated that oral-genital contact did not constitute having "had sex" with a partner. Nineteen percent responded similarly regarding penile-anal intercourse. CONCLUSIONS: The findings support the view that Americans hold widely divergent opinions about what behaviors do and do not constitute having "had sex."

Proliferative hemangiomas: analysis of cytokine gene expression and angiogenesis.

Hemangiomas are benign vascular tumors of childhood that can lead to disfigurement and/or life-threatening consequences. The pathogenesis of hemangioma formation is likely to involve increased angiogenesis. Basic fibroblast growth factor and vascular endothelial growth factor are cytokines that stimulate angiogenesis in multiple in vivo and in vitro models. Proliferative hemangiomas have been found to have elevated levels of basic fibroblast growth factor and vascular endothelial growth factor protein, but the gene expression of these cytokines in human specimens has not been previously studied. We examined the gene expression and spatial distribution of basic fibroblast growth factor and vascular endothelial growth factor messenger RNA in proliferative versus involuted human hemangioma specimens using nonisotopic in situ hybridization techniques. Thirteen hemangioma specimens were harvested during initial surgical excision. In situ hybridization was performed on frozen sections of both proliferative and involuted hemangioma specimens using genetically engineered antisense probes specific for basic fibroblast growth factor and vascular endothelial growth factor messenger RNA. Controls were an interleukin-6 sense sequence and a transforming growth factor-beta 1 antisense sequence. A large number of cells within the specimens of proliferative hemangiomas revealed localized gene expression of basic fibroblast growth factor and vascular endothelial growth factor messenger RNA (626 +/- 129 and 1660 +/- 371 cells/mm2, respectively). The majority of the cells were endothelial in origin. In contrast, involuted hemangioma specimens revealed significantly lower numbers of cells staining positive for basic fibroblast growth factor and vascular endothelial growth factor messenger RNA (44 +/- 11 and 431 +/- 76 cells/mm2, respectively; p < 0.05). Transforming growth factor-beta 1 messenger RNA was slightly more expressed by involuted hemangiomas (117 +/- 30 cells/mm2). There were very low levels of transforming growth factor-beta 1 gene expression from proliferative hemangiomas (37 +/- 24 cells/mm2; p < 0.02). These data demonstrate that (1) in situ hybridization allows identification and relative quantitation of cells expressing messenger RNA for specific growth factors in human hemangioma specimens; (2) basic fibroblast growth factor and vascular endothelial growth factor messenger RNA are up-regulated in proliferative hemangiomas; and (3) transforming growth factor-beta 1 messenger RNA remains low in both proliferative and involuted hemangiomas. Because basic fibroblast growth factor and vascular endothelial growth factor messenger RNA have been implicated in the pathobiology of human hemangioma formation, biochemical modulation of these angiogenic cytokines may eventually help inhibit proliferation and promote regression of hemangiomas.

A new model for heterotopic aortic valve transplantation.

A new model for heterotopic aortic valve transplantation in the rat is described. A composite allograft with an intact aortic valve and partial mitral valve was harvested from 4-month-old (400-450 g) Long-Evans rats and grafted heterotopically into the abdominal aorta of 4-week-old (80-100 g) rats with an optimal size match. At the end of a 1-month observation period, all experimental animals were alive and all showed 100% patency of the aortic valve allografts on microscopic evaluation after death (n=40). Unlike previously used methods, the proposed model allows for the preservation of all three aortic valve cusps and a more remote placement of the anastomotic suture line from the aortic valve annulus. The use of younger recipient rats improves size match and amplifies allograft calcification. The purpose of this study was to provide an animal model to evaluate modalities of preservation and chemical treatment for aortic valves used as allografts or bioprosthesis.

[Delayed effects of prenatal exposure to phenobarbital on intelligence--Phenemal]. / Intelligensdefekter som senfølge af praenatal eksposition for phenobarbital--fenemal.

Two double-blind studies were conducted on two independent samples of adult men prenatally exposed to phenobarbital and matched control samples using two different measures of general intelligence (WAIS and a draft board test (BPP)). The two studies included 33 and 81 exposed adult men respectively, and the two control groups included 52 and 101 unexposed men matched on a wide spectrum of maternal variables recorded pre- and perinatally. Based on data from control subjects, regression models were built relating intelligence scores to relevant pre-exposure matching variables. Models generated predicted scores for each exposed subject. Men exposed prenatally to phenobarbital had significantly lower verbal intelligence scores than predicted. Lower socioeconomic status and being the offspring of an unwanted pregnancy increased the magnitude of the negative effects. Exposure which includes the last trimester was the most detrimental. Physicians are urged to use increased caution in prescribing such medications during pregnancy or to premature neonates.

Psychometric properties of the Danish 16PF and EPQ.

A Danish translation of the Cattell's 16PF has been used in studies evaluating the effects of prenatal drug exposure. This paper reports a psychometric analysis of the 16PF and Eysenck's EPQ based on a sample of 558 young Danes. Many 16PF scales had unacceptable psychometric properties (as indicated by coefficient alpha and item--total score correlations), but more satisfactory results were obtained with the EPQ N and E scales. A factor analysis of all 16PF and EPQ scales suggested a six factor solution that roughly corresponds to the second-order factor structure obtained by Krug and Johns (1986). It is concluded that the second-order factor structure should be the basis of interpretation of the 16PF in both practical and research contexts.

In utero exposure to phenobarbital and intelligence deficits in adult men.

OBJECTIVE: To test whether exposure to phenobarbital in utero is associated with deficits in intelligence scores in adult men and whether the magnitude of the postnatal effect is mediated by exposure parameters and/or postnatal environmental factors. DESIGN: Two double-blind studies were conducted on independent samples of adult men prenatally exposed to phenobarbital and matched control samples using different measures of general intelligence. Based on data from control subjects, regression models were built relating intelligence scores to relevant pre-exposure matching variables and age at testing. Models generated predicted scores for each exposed subject. Group mean differences between the individually predicted and observed scores estimated exposure effects. SETTING: Copenhagen, Denmark. PARTICIPANTS: Exposed subjects were adult men born at the largest hospital in Copenhagen between 1959 and 1961 who were exposed to phenobarbital during gestation via maternal medical treatment and whose mothers had no history of a central nervous system disorder and no treatment during pregnancy with any other psychopharmacological drug. Study 1 included 33 men and study 2, 81 men. Controls were unexposed members of the same birth cohort matched on a wide spectrum of maternal variables recorded prenatally and perinatally. Controls for studies 1 and 2 included 52 and 101 men, respectively. MAIN OUTCOME MEASURES: In study 1: Wechsler Adult Intelligence Scale (Danish version); in study 2: Danish Military Draft Board Intelligence Test (Børge Priens Prøve). RESULT: Men exposed prenatally to phenobarbital had significantly lower verbal intelligence scores (approximately 0.5 SD) than predicted. Lower socioeconomic status and being the offspring of an "unwanted" pregnancy increased the magnitude of the negative effects. Exposure that included the last trimester was the most detrimental. CONCLUSION: Phenobarbital exposure during early development can have long-term deleterious effects on cognitive performance. Detrimental environmental conditions can interact with prenatal biological insult to magnify negative outcomes. Physicians are urged to use increased caution in prescribing such medications during pregnancy.

High-risk sexual behavior at a midwestern university: a confirmatory survey.

According to a 1991 study of sexual behavior based on a random sample of heterosexual undergraduates at a Midwestern university, 80% of the males and 73% of the females had experienced vaginal or anal intercourse. The average age at first vaginal intercourse was 17.2 years for both sexes. Seventeen percent of the sexually experienced males and 18% of the sexually experienced females had engaged in heterosexual anal intercourse; among these respondents, the average age at first anal intercourse was 20.3 for males and 19.1 for females. Although less than four years, on average, had elapsed since the respondents had first had vaginal intercourse, males reported an average of 8.0 lifetime vaginal-sex partners and females reported an average of 6.1. Overall, the findings from this random sample of students are similar to those from a 1988 convenience sample of the same college population.

Modulation of collagen synthesis by transforming growth factor-beta in keloid and hypertrophic scar fibroblasts.

Keloid and hypertrophic scars are fibrous growths characterized by overabundant collagen deposition. We examined the effect of transforming growth factor-beta (TGF-beta), a known stimulant for the production of connective tissue matrices, on the rate of collagen synthesis in keloid fibroblasts (KFs), hypertrophic scar fibroblasts (HSFs), and normal skin fibroblasts (NSFs). Fibroblasts were cultured in three-dimensional fibrin-gel matrices in the presence or absence of TGF-beta (5 ng/ml) or anti-TGF-beta neutralizing antibody (50 micrograms/ml). Secreted collagen levels, labeled with 3H-proline, were measured after 48 hours. KFs produced up to 12 times more collagen than NSFs, and up to 4 times more than HSFs. Although KFs increased their rate of collagen production by up to 2.7 times in response to TGF-beta, HSFs and NSFs did not (p = 0.065). Anti-TGF-beta antibody reduced the rate of collagen synthesis of KFs by 40% (p = 0.003), although it did not suppress collagen production in HSFs (p = 0.06) and NSFs (p = 0.75). We conclude that although KFs and HSFs are similar in that they both overproduce collagen, they are different in that only KFs display a marked sensitivity to TGF-beta, which is abundant during the proliferative phase of wound healing.

The Prenatal Development Project.

The primary aim of the Prenatal Development Project (PDP) is to evaluate the developmental effects of prenatal exposure to steroid hormones and psychoactive drugs, particularly synthetic progestin, corticosteroids and barbiturates. Data collection has taken place at the Psykologisk Institut, now the Institute of Preventive Medicine, since 1981. The PDP database is unique for its breadth and depth as well as its combination of prospective longitudinal and cross-sectional perspectives. This article describes the database, including subject selection, perinatal information, the comprehensive contemporary evaluation and archival information from Danish registers. The unique matching procedures designed specifically for these projects and data analytic strategies are explained. The value of the PDP database is discussed both in relation to specific project aims (evaluating effects of prenatal drug exposure) and in relation to developmental and psychological research in general.