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Biomedical subjects

C Hayward

Publications and source records attributed to C Hayward.

At least 37 records · Page 2Linked to original sources
PubMed1999

Salivary cortisol levels in socially phobic adolescent girls.

Anxiety disorders such as social phobia (SP) often have their onset during adolescence and frequently precede the onset of major depression. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is well-documented in major depression. Consequently, there is considerable interest in HPA function in anxiety disorders. We examined salivary cortisol levels in 27 SP adolescent girls and 21 matched controls during normal daily activities, and immediately before and after a modified Trier Social Stress Test (TSST). Both SP subjects and controls showed significant elevations in cortisol levels prior to the TSST, and prior to attending school. These results suggest that salivary cortisol is a sensitive measure of anticipatory anxiety, but we failed to find significant differences between SP subjects and controls.

Adolescent↗
PubMed1999

Aggregation and species coexistence of ectoparasites of marine fishes.

Interspecific interaction may lead to species exclusion but there are several ways in which species can coexist. One way is by reducing the overall intensity of competition via aggregated utilisation of fragmented resources. Known as the 'aggregation model of coexistence', this system assumes saturation and an equilibrium number of species per community. In this study we tested the effects of interspecific aggregation on the level of intraspecific aggregation among ectoparasites of marine fishes (36 communities of gill and head ectoparasite species). If parasite species are distributed in a way that interspecific aggregation is reduced relative to intraspecific aggregation then species coexistence is facilitated. We found a positive relationship between parasite species richness and fish body size, controlling for host phylogeny. A positive relationship between infracommunity species richness and total parasite species richness was also found, providing no evidence for saturation. This result supports the view that infracommunities of parasites are not saturated by local parasite residents. The observed lack of saturation implies that we are far from a full exploitation of the fish resource by parasites. Ectoparasites were aggregated at both population and species levels. However, only half of the ectoparasite communities were dominated by negative interspecific aggregation. We found that infracommunity parasite species richness was positively correlated with the level of intraspecific aggregation versus interspecific aggregation. This means that intraspecific aggregation increases compared with interspecific aggregation when total parasite species richness increases, controlling fish size and phylogeny. This supports one assumption of the 'aggregation model of coexistence', which predicts that interspecific interactions are reduced relative to intraspecific interactions, facilitating species coexistence.

Animals↗
PubMed1999

Gender differences in correlates of depressive symptoms in adolescents.

PURPOSE: To determine: (a) what demographic and psychosocial factors are associated with elevated levels of depressive symptoms in adolescence; (b) whether girls and boys show different profiles of correlates and probable risk factors for depressive symptoms; and (c) what the implications are of these results for future research directions and policy decisions. METHODS: Using a nationally representative sample of adolescent school students in Grades 5-12, the Commonwealth Fund Adolescent Health Survey assessed depressive symptoms as well as a number of variables posited to be risk factors and correlates of depression. RESULTS: Depressive symptoms were found to differ by gender, age, socioeconomic status, and ethnicity. In addition, life stress, social support, and coping were associated with depressive symptoms. Importantly, stress and social support appear to be particularly salient aspects of depression among girls. Both physical and sexual abuse were strongly linked with depression for both boys and girls, with sexual abuse having a stronger impact among boys. Finally, high levels of depressive symptoms were associated with increased use of both mental and physical health care resources among boys and girls. CONCLUSIONS: The correlates of depression in this adolescent sample closely resemble those seen in adult samples, including demographic and psychosocial variables. Some psychosocial variables, such as stress and social support, may have a greater impact on depressive symptoms for girls than for boys. Results of this study also have important implications for the health care system, given that higher levels of depressive symptoms were found to be associated with greater utilization of physical health care resources.

Adaptation, Psychological↗
PubMed1999

Ethnic differences in the association between pubertal status and symptoms of depression in adolescent girls.

PURPOSE: To examine the importance of chronologic age versus pubertal status in predicting adolescent girls' depressive symptoms in different ethnic groups. METHODS: A national probability sample was used to obtain a representative cohort of 3216 adolescents, 5th through 8th grades. Subjects completed a questionnaire, which included a modified version of the Children's Depression Inventory (CDI) and an assessment of timing of menarche. RESULTS: Among Caucasians, post-menarcheal adolescent girls had higher depression scores than did same-aged pre-menarcheal girls. Boys and pre-menarcheal girls had similar depression scores in most age groups. Among African-Americans and Hispanics, there were no menarche-associated differences in depressive symptoms. CONCLUSION: In early adolescence pubertal status is a better predictor of depressive symptoms than chronological age in Caucasian, but not African-American or Hispanic girls.

Adolescent↗
PubMed1999

Naturalistic weight-reduction efforts prospectively predict growth in relative weight and onset of obesity among female adolescents.

This study examined the prospective relations of naturalistic weight-reduction efforts to growth in relative weight and onset of obesity with data from a community study of female adolescents (N = 692). Initial self-labeled dieting, appetite suppressant/laxative use, incidental exercise, vomiting for weight-control purposes, and binge eating predicted elevated growth in relative weight over the 4-year period. Dietary restraint, self-labeled dieting, exercise for weight-control purposes, and appetite suppressant/laxative use predicted an increased risk for obesity onset. Data imply that the weight-reduction efforts reported by adolescents are more likely to result in weight gain than in weight loss and suggest the need to educate youth on more effective weight-control strategies.

Adolescent↗
PubMed1999

Phylogenetic relationships among members of the Comamonadaceae, and description of Delftia acidovorans (den Dooren de Jong 1926 and Tamaoka et al. 1987) gen. nov., comb. nov.

The phylogenetic relationships among members of the family Comamonadaceae and several unclassified strains were studied by direct sequencing of their PCR-amplified 16S rRNA genes. Based on the 16S rRNA gene sequence analysis, members of the family formed a coherent group. The closest relatives are species of the Rubrivivax sub-group: Leptothrix discophora, Ideonella dechloratans and Rubrivivax gelatinosus. The genus Hydrogenophaga formed two subclusters, as did the species of Acidovorax, whereas the five species of the genus [Aquaspirillum] were polyphyletic. Comamonas acidovorans was phylogenetically distant from the type species of Comamonas, Comamonas terrigena. On the basis of this work and previous studies, Comamonas acidovorans is removed from the genus Comamonas and renamed as Delftia acidovorans gen. nov., comb. nov. Descriptions of the new genus Delftia and of the type species Delftia acidovorans, for which the type strain is ATCC 15668T, are presented.

DNA, Bacterial↗
PubMed1999

Description of Gluconacetobacter sacchari sp. nov., a new species of acetic acid bacterium isolated from the leaf sheath of sugar cane and from the pink sugar-cane mealy bug.

A new species of the genus Gluconacetobacter, for which the name Gluconacetobacter sacchari sp. nov. is proposed, was isolated from the leaf sheath of sugar cane and from the pink sugar-cane mealy bug, Saccharicoccus sacchari, found on sugar cane growing in Queensland and northern New South Wales, Australia. The nearest phylogenetic relatives in the alpha-subclass of the Proteobacteria are Gluconacetobacter liquefaciens and Gluconacetobacter diazotrophicus, which have 98.8-99.3% and 97.9-98.5% 16S rDNA sequence similarity, respectively, to members of Gluconacetobacter sacchari. On the basis of the phylogenetic positioning of the strains, DNA reassociation studies, phenotypic tests and the presence of the Q10 ubiquinone, this new species was assigned to the genus Gluconacetobacter. No single phenotypic characteristic is unique to the species, but the species can be differentiated phenotypically from closely related members of the acetic acid bacteria by growth in the presence of 0.01% malachite green, growth on 30% glucose, an inability to fix nitrogen and an inability to grow with the L-amino acids asparagine, glycine, glutamine, threonine and tryptophan when D-mannitol was supplied as the sole carbon and energy source. The type strain of this species is strain SRI 1794T (= DSM 12717T).

Acetobacteraceae↗
PubMed1998

Antibody repertoire development in fetal and neonatal piglets. I. Four VH genes account for 80 percent of VH usage during 84 days of fetal life.

VDJ rearrangement and VH gene usage during fetal development in 35 outbred piglets was examined by PCR amplification of VDJs; VDJs were subsequently characterized by hybridization with VH-specific gene probes and by sequencing. VDJ rearrangement was first seen in the fetal liver on day 30 of a 114-day gestation. Four VH genes (V(H)A, V(H)B, V(H)C, and V(H)E) accounted for approximately 80% of all VH gene usage regardless of gestational age, choice of piglet, or lymphoid tissue tested; D(H)A and D(H)B were used in >90% of the fetal VDJs examined. Evidence of somatic hypermutation during fetal development was not found. The proportion of the four prominent fetal VH genes did not differ significantly between cDNA and DNA, suggesting the absence of selective B cell differentiation. A comparison of recombination signal sequences, flanking sequences, and framework sequences of these fetal genes with other germline VH genes of swine offered no clue as to their selective usage. N-region additions were prominent on day 40 but not on day 30, suggesting that the onset of terminal deoxynucleotidyltransferase activity occurs after 30 days of fetal development. These collective findings indicate that the preimmune, "natural Ab" repertoire of the fetal piglet is largely restricted to the use of four nonpolymorphic and nonmutated VH genes and two nonmutated DH segments. This suggests that the preimmune repertoire of swine is either highly restricted or almost entirely determined by junctional diversity in complementarity-determining region-3.

Animals↗
PubMed1998

Marfan Database (third edition): new mutations and new routines for the software.

The Marfan database is a software that contains routines for the analysis of mutations identified in the FBN1 gene that encodes fibrillin-1. Mutations in this gene are associated not only with Marfan syndrome but also with a spectrum of overlapping disorders. The third version of the Marfan database contains 137 entries. The software has been modified to accommodate four new routines and is now accessible on the World Wide Web at http://www.umd.necker.fr

Computer Communication Networks↗
PubMed1998

Age of onset for binge eating and purging during late adolescence: a 4-year survival analysis.

This prospective study examined age of onset for binge eating and purging among girls during late adolescence and tested whether dieting and negative affectivity predicted these outcomes. Of initially asymptomatic adolescents, 5% reported onset of objective binge eating, 4% reported onset of subjective binge eating, and 4% reported onset of purging. Peak risk for onset of binge eating occurred at age 16, whereas peak risk for onset of purging occurred at age 18. Adolescents more often reported onset of a single symptom rather than multiple symptoms, and symptoms were episodic. Dieting and negative affectivity predicted onset of binge eating and purging. Findings suggest that late adolescence is a high-risk period for onset of bulimic behaviors and identify modifiable risk factors for these outcomes.

Adolescent↗
PubMed1998

Linking self-reported childhood behavioral inhibition to adolescent social phobia.

OBJECTIVE: Behavioral inhibition in children has been hypothesized to be a risk factor for the later development of social phobia. However, this hypothesis has yet to be demonstrated in a prospective study. The purpose of the study presented here is to test whether behavioral inhibition in childhood constitutes a risk factor for social phobia during adolescence. METHOD: The sample consisted of 2,242 high school students assessed over a 4-year period. Assessments included self-report questionnaires, structured clinical interviews, and measurements of heart rate. Cox proportional hazards models were used to evaluate risk. RESULTS: Social avoidance, a component of behavioral inhibition, predicted onset of social phobia during high school. However, social avoidance was not related to depression in adolescence. Another component of behavioral inhibition, fearfulness, increased the risk for both social phobia and depression. Among subjects who were both socially avoidant and fearful, 22.3% developed social phobia--a risk more than four times greater than that for subjects with neither feature of behavioral inhibition. CONCLUSION: This prospective study demonstrates that behavioral inhibition in childhood increases the risk of social phobia in adolescence.

Adolescent↗
PubMed1998

Beckwith-Wiedemann syndrome in a child with chromosome 18q deletion.

Molecular genetic investigation of a female infant with Beckwith-Wiedemann syndrome (BWS) showed loss of IGF2 imprinting but no evidence of uniparental disomy. In addition, a deletion of chromosome 18q22.1 was identified in this infant without clinical features of 18q-syndrome (microcephaly, short stature, hypotonia). The association of a chromosome 18 deletion and BWS may be coincidental or may indicate the location of a trans activating regulator element for maintenance of IGF2 imprinting.

Beckwith-Wiedemann Syndrome↗
PubMed1998

Support for the continuity hypothesis of bulimic pathology.

There has been debate as to whether bulimia represents the endpoint of an eating disorder continuum (the continuity hypothesis) or is categorically different from subthreshold bulimia or an absence of eating disorders (the discontinuity hypothesis). The present study tested whether differences among bulimic, subthreshold bulimic, and control women on weight-concern and psychopathology variables better accord with the continuity or discontinuity hypothesis. These 3 groups were compared on body mass, thin-ideal internalization, body dissatisfaction, dietary restraint, depressive symptoms, anxiety symptoms, and temperamental emotionality. Discriminant function analysis and follow-up pairwise contrasts indicated that the continuity hypothesis was supported for measures of both weight concern and psychopathology. Research and treatment implications of the continuity perspective are discussed.

Adolescent↗