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Biomedical subjects

S Bryson

Publications and source records attributed to S Bryson.

At least 19 recordsLinked to original sources
PubMed2001

Piracetam therapy does not enhance cognitive functioning in children with down syndrome.

BACKGROUND: Piracetam is widely used as a purported means of improving cognitive function in children with Down syndrome. Its efficacy, however, has not been rigorously assessed. OBJECTIVE: To determine whether 4 months of piracetam therapy (80-100 mg/kg per day) enhances cognitive function in children with Down syndrome. DESIGN: A randomized, double-blind, placebo-controlled crossover study. PARTICIPANTS AND METHODS: Twenty-five children with Down syndrome (aged 6.5-13 years) and their caregivers participated. After undergoing a baseline cognitive assessment, children were randomly assigned to 1 of 2 treatment groups: piracetam-placebo or placebo-piracetam. MAIN OUTCOME MEASURE: The difference in performance while taking piracetam vs while taking placebo on tests assessing a wide range of cognitive functions, including attention, learning, and memory. RESULTS: Eighteen children completed the study, 4 withdrew, and 3 were excluded at baseline. Piracetam therapy did not significantly improve cognitive performance over placebo use but was associated with central nervous system stimulatory effects in 7 children: aggressiveness (n = 4), agitation or irritability (n = 2), sexual arousal (n = 2), poor sleep (n = 1), and decreased appetite (n = 1). CONCLUSION: Piracetam therapy did not enhance cognition or behavior but was associated with adverse effects.

Adolescent↗
PubMed2001

Early body mass index and other anthropometric relationships between parents and children.

OBJECTIVE: To assess longitudinally the relationship between measures of adiposity in children over the first 8 y of life with that of their parents and to explore the role of parental adiposity in the development of childhood adiposity. DESIGN: Longitudinal study of measures of adiposity in children. SUBJECTS: A community sample from three health service systems including 114 children followed annually from infancy to age 8 and their 228 biological parents. METHODS: Measurements were assessed at baseline for parents (6 months post-partum for mothers) and at regular intervals for children beginning at age 2 months. Measurements included weight, height, triceps skinfold, subscapular skinfold, midarm circumference, waist and hip. RESULTS: The major findings were: (1) significant correlations between parental body mass index (BMI), both maternal and paternal, and their biological offspring first emerged at age 7; (2) children with two overweight parents had consistently elevated BMI compared to children with either no overweight parents or one overweight parent. These differences became significant beginning at age 7. CONCLUSIONS: This study supports the hypothesis that familial factors (biological and/or environmental) affecting the development of adiposity emerge at specific ages and are related to the adiposity of both parents.

Adult↗
PubMed2001

Prolonged bottle feeding in a cohort of children: does it affect caloric intake and dietary composition?

Little is known about the consequences to children of bottle feeding prolonged beyond age 1 year on caloric intake and overall dietary composition. To obtain these data, 165 children, followed up from infancy, were assessed in these respects for a 24-hour period at age 3 1/2 years. Bottle-fed children (n = 14) consumed more milk than their weaned counterparts (p < 0.001), had a higher mean daily calcium intake (p < 0.05), received fewer calories from carbohydrates (p = 0.034), and received a greater percentage of calories from protein (p = 0.033). There were no significant differences between the groups in total caloric intake, total iron intake, total volume ofjuice, or calories from fat. Pediatricians questioned about the effects of continuing to offer children nutritive liquids from bottles as well as cups (versus offering cups alone) may inform parents that this feeding practice is associated with significantly greater milk consumption and daily calcium intake. However, this study could not find evidence that prolonged bottle feeding at age 3 1/2 years is associated with a significantly decreased total daily iron intake or an increased risk for factors associated with adiposity such as a greater daily calorie intake, a higher body mass index, or greater percentage of total calories derived from fat.

Animals↗
PubMed2001

Repeated doses of porcine secretin in the treatment of autism: a randomized, placebo-controlled trial.

BACKGROUND AND OBJECTIVES: Anecdotal reports on the efficacy of secretin in autism raised great hopes for the treatment of children with this disorder. Initial single-dose, randomized, controlled trials failed to demonstrate any therapeutic effects of secretin. The present study is the first to test the outcome of repeated doses and to examine whether there is a subgroup of children who are more likely to achieve positive effects. METHOD: Sixty-four children with autism (ages 2-7 years; 55 boys and 9 girls) with a range of intelligence quotient and verbal ability were randomly assigned, in a double-blind manner, to secretin or placebo groups. Children received 2 doses of placebo or porcine secretin, 6 weeks apart. Assessments were performed at baseline and 3 weeks after each injection using several outcome measures. RESULTS: There were no group differences on formal measures of language, cognition, or autistic symptomatology. Subgroupings based on cognitive level, the presence or absence of diarrhea, or a history of regression failed to show any significant therapeutic effects of secretin. CONCLUSION: No evidence is provided for the efficacy of repeated doses of porcine secretin in the treatment of children with autism. The possible relationship between relief of biological symptoms and enhanced skill performance is discussed.

Analysis of Variance↗
PubMed2000

High functioning autism and Childhood Disintegrative Disorder in half brothers.

Childhood Disintegrative Disorder (CDD) is grouped with autism as a subtype of Pervasive Developmental Disorder (PDD) in ICD-10 and DSM-IV. This is the first report of autism and CDD cosegregating within a sibship. J. P. and M. P. are half-brothers with the same mother. J. P. is an 18-year-old with impairments in communication, social reciprocity, and stereotypies and was diagnosed with autism. M. P. is a 7-year-old who developed normally to 2 years 4 months. He then underwent a profound regression, becoming nonverbal and socially withdrawn, and lost adaptive skills. Investigations did not reveal any neurodegenerative process. M. P. was diagnosed with CDD. The rarity of the two conditions suggests a shared transmissible mechanism. The implications for autism/PDD genetic studies are discussed.

Adolescent↗
PubMed2000

The role of police dogs as companions and working partners.

Written responses to a questionnaire by 255 officers who used canines in police work were assessed. Almost all officers frequently played with, talked to, petted, and brushed their dogs and believed the dogs benefitted their health and well-being. Officers whose dogs slept indoors, often in the same bedroom, generally said they loved their dogs and they described their dogs as calm rather than active, as indicated by a multiple correspondence analysis. These 96 officers more than the 154 officers whose dogs slept outdoors or in kennels also planned to remain in canine work. Although departments often assumed responsibility for purchasing the dogs, the more experienced officers usually were involved in the final selection of dogs (logistic regression: p < .0001). Compared with 94 officers not involved in selecting their dogs, 106 officers with a specific role in selecting their dogs planned to stay in canine work, as shown by a multiple correspondence analysis. They believed the dogs had saved their lives (p < .01). Over-all, officers reported spending 4.1 hr. on-duty and 2.9 hr. off-duty per week training their dogs, and also played with them for 6.5 hr. per week, assuring a regular pattern of exercise for the officers. Virtually all officers valued canine service and believed the dogs enhanced the department's effectiveness. This study showed that both close companionship with the dog and involvement in selecting the dog were associated both with satisfaction with the dog and with working as a canine officer.

Adult↗
PubMed1999

Development of feeding practices during the first 5 years of life.

OBJECTIVE: To understand the transition from breast-and bottle-feeding to solid-feeding and factors that might affect the duration of breast- and bottle-feeding. DESIGN: Cohort followed up from birth with relatively well-educated, middle-class parents. SETTING: Community sample recruited from 3 suburban newborn nurseries (a teaching hospital, community hospital, and large health maintenance organization). PARTICIPANTS: One hundred ninety-one healthy full-term infants. MEASURES: Assessment of feeding practices through the ages of complete weaning from breast- and bottle-feeding. RESULTS: More than 90% of participants breast-fed for at least 2 weeks. Infants of older mothers were weaned from the breast later than infants of younger mothers. First-born infants were weaned from the breast earlier than later-born infants. Eighty-four percent of infants bottle-fed at some time during the first year of life. More than 40% of the cohort was still receiving bottles at 24 months of age, 16% at 36 months, and 8% at 48 months. The duration of breast- and bottle-feeding was related to maternal work status; mothers who returned to work during the first 3 months postpartum weaned sooner from the breast and later from the bottle than women who returned to work after 3 months postpartum. CONCLUSIONS: The frequency of late bottle-weaning in this well-educated, middle-class cohort was unexpected and was related to the timing of the mother's return to work. The impact of prolonged bottle-feeding on later growth and adiposity deserves further investigation.

Adult↗
PubMed1999

Development and evaluation of the McKnight Risk Factor Survey for assessing potential risk and protective factors for disordered eating in preadolescent and adolescent girls.

OBJECTIVE: To describe the development, test-retest reliability, internal consistency, and convergent validity of the McKnight Risk Factor Survey-III (MRFS-III). The MRFS-III was designed to assess a number of potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls. METHOD: Several versions of the MRFS were pilot tested before the MRFS-III was administered to a sample of 651 4th through 12th- grade girls to establish its psychometric properties. RESULTS: Most of the test-retest reliability coefficients of individual items on the MRFS-III were r > .40. Alpha coefficients for each risk and protective factor domain on the MRFS-III were also computed. The majority of these coefficients were r > .60. High convergent validity coefficients were obtained for specific items on the MRFS-III and measures of self-esteem (Rosenberg Self-Esteem Scale) and weight concerns (Weight Concerns Scale). CONCLUSIONS: The test-retest reliability, internal consistency, and convergent validity of the MRFS-III suggest that it is a useful new instrument to assess potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls.

Adolescent↗
PubMed1999

Can mothers influence their child's eating behavior?

This study examined the relationship between general maternal parenting style, maternal eating cues, and a child's eating behavior during mealtime. We expected that the general style would relate to the number of specific eating cues and that mothers who used more eating prompts would have children that ate more and at a faster rate. Seventy-seven children (39 girls, 38 boys), aged 3.5 years, visited the laboratory with their mothers for a videotaped lunch. Videotapes of each laboratory visit were coded for the child's eating rate and maternal parenting style, which was measured as the level of maternal control and support and the number and type of eating prompts given during a meal. Caloric intake was also calculated. The number and rate of verbal and physical encouragements and discouragements were significantly related to measures of general maternal parenting style and meal duration. The rates of food offers, food presentations, and total prompts were all significantly related to the child's rate of calorie intake. However, a mother's level of support or control was not related to the child's eating behavior. Although general maternal parenting style did not predict the child's eating behavior, these behaviors were related to the frequency of maternal eating prompts, which in turn were significantly related to the number of calories eaten and the time spent eating by the child. Children who ate the fastest had mothers who delivered eating prompts at a higher frequency. These findings may have implications for the development of obesity later in childhood, as a function of rapid eating or of poor self-regulation.

Child Behavior↗
PubMed1998

The malignant capacity of skin tumours induced by expression of a mutant H-ras transgene depends on the cell type targeted.

BACKGROUND: . Pinpointing the cells from which tumours arise is a major challenge n tumour biology. Previous work has shown that the targeted expression of a mutant ras gene within the interfollicular cell compartment of mouse skin induces the formation of benign papillomas, but these do not spontaneously progress to malignancy. We have investigated the carcinogenic effects of expressing the same oncogene in a different population of epidermal cells. RESULTS: Expression of mutant ras from a truncated keratin 5 gene promoter, which directs expression to the follicular and interfollicular cells of newborn mice and the hair follicle cells of adults, stimulated the development of acanthotic areas in newborn mice. Within one week of birth, the acanthotic skin developed areas of carcinoma in situ and adult mice developed papillomas and keratoacanthomas, the latter having a high frequency of spontaneous malignant transformation to squamous and occasionally spindle carcinomas. The benign tumours that arose had several hallmarks of tumours at a high risk of malignant progression, including suprabasal cell proliferation and heterogeneous expression of keratin 13. In contrast to tumours induced by expressing mutant ras under the control of the keratin 10 or keratin 1 gene promoters, the formation of these lesions was not dependent on wounding or a tumour promoter. CONCLUSIONS: Benign tumours that are at a risk of malignant conversion are primarily derived from cells located within the hair follicle, and the nature of the cell in which tumour initiation occurs is a major determinant of malignant potential.

Animals↗
PubMed1998

Factors associated with weight concerns in adolescent girls.

OBJECTIVE: This study examined the association of weight concerns with potential risk factors for the development of eating disorders. METHOD: A self-report survey was given to 103 elementary (Grades 4 and 5) and 420 middle (Grades 6-8) school students in Arizona and California. Of these, 78 elementary and 333 middle school students provided complete data and were used in the analyses. RESULTS: In a multivariate stepwise regression analysis, the importance that peers put on weight and eating was most strongly related to weight concerns in the elementary school girls, accounting for 34% of the variance after adjusting for site differences. Trying to look like girls/women on TV and in magazines as well as body mass index (BMI) entered the final model that accounted for 57% of the variance in weight concerns. In middle school, the importance that peers place on weight and eating was also the strongest predictor accounting for 33% of the variance followed by confidence, BMI, trying to look like girls/women on TV and in magazines, and being teased about weight. Together these variables accounted for 55% of the variance. DISCUSSION: Prevention programs aimed at reducing weight concerns need to address these factors.

Adolescent↗
PubMed1996

TGFbeta1 inhibits the formation of benign skin tumors, but enhances progression to invasive spindle carcinomas in transgenic mice.

TGFbeta1 has been implicated in cell cycle control and carcinogenesis. To address the exact function of TGFbeta1 in skin carcinogenesis in vivo, mice with TGFbeta1 expression targeted to keratinocytes were subjected to long-term chemical carcinogenesis treatment. TGFbeta1 showed biphasic action during multistage skin carcinogenesis, acting early as a tumor suppressor but later enhancing the malignant phenotype. The transgenics were more resistant to induction of benign skin tumors than controls, but the malignant conversion rate was vastly increased. There was also a higher incidence of spindle cell carcinomas, which expressed high levels of endogenous TGFbeta3, suggesting that TGFbeta1 elicits an epithelial-mesenchymal transition in vivo and that TGFbeta3 might be involved in maintenance of the spindle cell phenotype. The action of TGFbeta1 in enhancing malignant progression may mimic its proposed function in modulating epithelial cell plasticity during embryonic development.

Animals↗
PubMed1996

High phenotypic correlations among siblings with autism and pervasive developmental disorders.

The objective of this study was to examine familial factors influencing clinical variation in sibships that contained at least 2 children affected with autism or another form of pervasive developmental disorder (PDD). The sample included a total of 60 families, 23 with multiple cases of PDD and 37 with a single affected child. Measurements of IQ, adaptive behaviors in socialization and communication, and autistic symptoms were taken on all affected children. A high intraclass correlation, especially on IQ and an index of social behaviors, was observed between affected children from the same family. In contrast, low correlations were observed on measurements of IQ and adaptive behavior between affected and unaffected children from the same family. These data indicate that variation in severity of PDD is influenced by familial, and probably genetic, mechanisms. The results are discussed in relation to current theories on the genetics of autism and the heritable mechanisms underlying variations in clinical severity.

Autistic Disorder↗
PubMed1996

Multigenic control of skin tumour development in mice.

Different inbred mouse strains vary greatly in their susceptibility to tumour development in a variety of tissues. Intraspecific and interspecific crosses can, therefore, be used to map the loci that control this predisposition. Crosses of Mus musculus with Mus spretus are highly resistant to tumour development in the skin, liver, lung and lymphoid system. M. spretus, therefore, has dominantly acting resistance loci, which we have attempted to map. More than 350 interspecific backcross mice were followed for 18 months to assess susceptibility to development of chemically induced papillomas and carcinomas. The results were analysed using a combination of MAPMAKER/QTL analysis and multiple regression analysis for the determination of linkage in multigenic quantitative traits. The results showed clearly that at least three genes on chromosomes 5 and 7 control resistance to tumour development. Importantly, some genes confer resistance to benign tumours but they have relatively little effect on malignant progression. This suggests the existence of different classes of benign tumours: those that are capable of tumour progression and those that have only a very low probability of becoming malignant. Identification of these genes will improve our understanding of mechanisms of carcinogenesis and may provide a novel route to the identification of "low-penetrance' human tumour susceptibility genes.

Animals↗
PubMed1996

Multiple method validation study of facilitated communication: II. Individual differences and subgroup results.

Potential individual variations in the effectiveness of a shared communication method, facilitated communication (FC), were examined among 20 students with autism and related disorders. To minimize the limits or disadvantages of a single method, we used multiple methods, including auditory or visual input, and simple pointing responses to pictures or words, as well as typing. Data were collected after 6 weeks of FC, and follow-up data up to 7 months later. Findings differed across methods, but there was little clear support for the validity of FC in enhancing communication over communication that students produced independently. Significant facilitator influence of responses was found, but was far less extensive than in other studies. However, an "abdication" pattern of responding was found for some students, in which high performance observed with independent responding was lessened on trials when FC was introduced. That is, these students may become more passive communicators when FC is used. The complex detected and undetected influences in the process of communication through facilitation are discussed, as well as risk factors in the use of FC.

Adolescent↗
PubMed1995

Concerted action of TGF-beta 1 and its type II receptor in control of epidermal homeostasis in transgenic mice.

Transforming growth factor-beta 1 (TGF-beta 1) is a modulator of cellular proliferation, differentiation, and extracellular matrix deposition. It is a potent epithelial growth inhibitor and can alter the differentiative properties of keratinocytes, in vitro, but little is known about its normal physiological function in the epidermis in vivo. Transgenic mice were generated using a keratin 10 (K10) gene promoter to drive constitutive expression of TGF-beta 1 in the suprabasal keratinocyte compartment. Surprisingly, these mice showed a two- to threefold increase in epidermal DNA labeling index over control mice, in the absence of hyperplasia. The transgene, however, acted in the expected fashion, as a negative regulator of cell growth, when hyperplasia was induced by treatment by 12-tetradecanoyl-phorbol-13-acetate (TPA). Epidermal TGF-beta type I and II receptor (T beta RI and T beta RII) levels were examined in control and transgenic mice during induction of hyperplasia by TPA. Whereas T beta RI levels remained relatively constant, T beta RII expression was strongly induced in TPA-treated skins, prior to the induction of the growth inhibitory response to TGF-beta 1, and its level of expression correlated with growth sensitivity to TGF-beta 1 in vivo and in vitro. These results suggest that TGF-beta 1 and its type II receptor are part of the endogenous homeostatic regulatory machinery of the epidermis.

Activin Receptors, Type I↗
PubMed1995

Distinct genetic loci control development of benign and malignant skin tumours in mice.

Genetic susceptibility to chemically induced skin cancer in mice is controlled by multiple unlinked genetic loci. Mus spretus mice have dominant resistance genes which confer resistance to interspecific F1 hybrids with susceptible Mus musculus strains. We have mapped three major resistance loci using a combination of Mapmaker/QTL analysis and multiple regression analysis to mouse chromosomes 5 and 7. At least two independent loci on chromosome 7 exert their effects primarily during benign tumour development and have very little influence on tumour progression. On the other hand, probably a single locus on chromosome 5 affects both early and late stages of malignancy. The results indicate that benign and malignant tumours are largely under independent genetic control.

Animals↗