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Biomedical subjects

J C Carter

Publications and source records attributed to J C Carter.

At least 19 recordsLinked to original sources
PubMed2006

Observations in collinear femtosecond-nanosecond dual-pulse laser-induced breakdown spectroscopy.

In the work reported herein, we have combined a short-lived femtosecond laser-induced plasma (LIP) and a longer-lived nanosecond LIP in a collinear pulse configuration to examine the source(s) of atomic emission and signal-to-noise enhancement in dual-pulse laser-induced breakdown spectroscopy (LIBS). Initial studies indicate that the primary source of dual-pulse LIBS enhancement in the collinear configuration may in large part be a matter of pulse focus; focusing on the sample surface, for example, yields atomic emission enhancements whose lifetime correlates reasonably well with the femtosecond LIP emissive lifetime, suggesting that plasma-plasma coupling may play an important role at that pulse focus. At a second "optimal" focal position above the sample surface, alternatively, atomic emission and signal-to-noise enhancements correlate quite well with the nitrogen and oxygen atomic emission reductions previously seen following use of a femtosecond air spark and a nanosecond ablative pulse in the orthogonal dual-pulse configuration, suggesting that pressure or number density reductions due to femtosecond LIP formation in air may be significant at that pulse focus.

Equipment Design↗
PubMed2004

Relapse in anorexia nervosa: a survival analysis.

BACKGROUND: Knowledge about factors that predict relapse in anorexia nervosa (AN) is needed for the development of effective relapse prevention treatments and may also advance understanding of the psychopathology of AN. The aim of the present study was to examine the rate, timing and prediction of relapse in AN following weight restoration in a specialized in-patient treatment programme. METHOD: Fifty-one consecutive first-admission AN patients who were weight-restored following in-patient treatment participated in the study. Follow-up assessments were conducted a median of 15 months post-discharge. Relapse of AN was defined as a body mass index <17.5 for 3 consecutive months. Data were analysed using Kaplan-Meier survival analysis and Cox regression. RESULTS: The overall rate of relapse was 35% and the mean survival time was 18 months. The highest risk period was from 6 to 17 months after discharge. Several significant predictors of relapse were identified: a history of suicide attempt; previous specialized treatment for an eating disorder; severity of obsessive-compulsive symptoms at presentation; excessive exercise immediately after discharge; and residual concern about shape and weight at discharge. CONCLUSIONS: There continues to be a significant risk of relapse among AN patients who remain well for the first year post-discharge. Several variables were shown to be associated with an elevated risk of relapse. These findings have implications for the development of initial treatments and relapse prevention strategies for AN.

Adaptation, Psychological↗
PubMed2001

Modification of eating attitudes and behavior in adolescent girls: A controlled study.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a school-based eating disorder prevention program designed to reduce dietary restraint and concern about shape and weight among adolescent girls. METHOD: A total of 474 girls aged 13-14 years received the program as part of their normal school curriculum. An assessment-only control group included 386 pupils. Measures of eating disorder features, self-esteem, and knowledge were administered before and after the intervention and at 6-month follow-up. RESULTS: Immediately following the intervention, there was a small reduction in dietary restraint and attitudes to shape and weight in the index group, whereas there was no change in the control group. This reduction was not maintained at 6-month follow-up although the dietary restraint scores of the index group remained lower than those of the control group. DISCUSSION: This prevention program achieved change in eating attitudes and behavior, although the change was modest in size and not sustained. Focusing on a high-risk subgroup of dieters might be a more fruitful primary prevention strategy.

Adolescent↗
PubMed2001

Pretreatment motivational enhancement therapy for eating disorders: a pilot study.

UNLABELLED: Eating disorder patients are notoriously ambivalent about treatment and often lack motivation to change. These characteristics may decrease the number of patients entering treatment and increase the number of patients dropping out of treatment prematurely. OBJECTIVE: The aim of this pilot study was to develop and evaluate a motivational enhancement therapy (MET) group program for eating disorder patients. The goal of the MET intervention was to increase participants' motivation to change, which might be expected to increase the success of future treatment of patients with eating disorders. METHOD: Nineteen individuals who were referred for specialized treatment took part in the study. The intervention was based on existing literature in the field of addictions and modified for eating disorders. RESULTS: The motivational measures suggested that the participants' motivation to change increased following the intervention. A decrease in depressive symptoms and an increase in self-esteem were also found. DISCUSSION: The results of this study suggest that MET could be valuable for the treatment of eating disorder patients and provide a rationale to conduct further research in this area.

Adolescent↗
PubMed2001

Assessment of bulimia nervosa: a comparison of interview and self-report questionnaire methods.

OBJECTIVE: The main aim of this study was to assess the level of agreement between the Eating Disorders Examination (EDE) and its self-report version (EDE-Q) on key items in a clinic sample of patients with bulimia nervosa. A second objective was to assess the concordance between self-reported and objective body weight in the sample. METHOD: Sixty females who met DSM-IV criteria for bulimia nervosa (purging type) participated. Fifty-seven of them completed both the EDE and the EDE-Q. Self-reported weight was obtained during a telephone screening interview. Objective weight was subsequently measured at an assessment about a week later. RESULTS: The EDE generated higher scores than the EDE-Q for the frequency of objective binge and vomiting episodes. The two methods produced equivalent results for subjective binge episodes, laxative and diuretic misuse, and concerns about shape and weight. The self-report method underestimated body weight. DISCUSSION: These findings suggest that some core features of eating disorders are more accurately assessed using the EDE interview.

Adult↗
PubMed2001

Eating disorder examination questionnaire: norms for young adolescent girls.

This paper reports young adolescent female norms for the Eating Disorder Examination Questionnaire (EDE-Q). The standardization sample was comprised of 808 girls aged between 12 and 14 years from three single-sex schools (one private and two state schools). Means, standard deviations and percentile ranks for raw EDE-Q subscale scores are presented. Prevalence figures for key eating disorder behaviors over the previous two weeks were as follows: 4% self-induced vomiting; 1% laxative misuse; 0.4% diuretic misuse; and 8% regular binge eating.

Adolescent↗
PubMed2001

Matching patient variables to treatment intensity. The continuum of care.

This article has reviewed what is currently known regarding the relationship between specific patient variables and treatment response in AN, BN, and BED. Matching patient variables to treatment intensity remains an important and fruitful area for future research. There is a need for established guidelines for clinicians regarding the choice of the appropriateness of treatment settings and type of interventions delivered in those settings. These guidelines should be evidence based, with clear clinical indicators for each of the recognized eating disorders and their subclinical variants.

Continuity of Patient Care↗
PubMed2001

The maternal gene spn-4 encodes a predicted RRM protein required for mitotic spindle orientation and cell fate patterning in early C. elegans embryos.

C. elegans embryogenesis begins with a stereotyped sequence of asymmetric cell divisions that are largely responsible for establishing the nematode body plan. These early asymmetries are specified after fertilization by the widely conserved, cortically enriched PAR and PKC-3 proteins, which include three kinases and two PDZ domain proteins. During asymmetric cell divisions in the early embryo, centrosome pairs initially are positioned on transverse axes but then rotate to align with the anteroposterior embryonic axis. We show that rotation of the centrosomal/nuclear complex in an embryonic cell called P(1) requires a maternally expressed gene we name spn-4. The predicted SPN-4 protein contains a single RNA recognition motif (RRM), and belongs to a small subfamily of RRM proteins that includes one Drosophila and two human family members. Remarkably, in mutant embryos lacking spn-4 function the transversely oriented 'P(1)' mitotic spindle appears to re-specify the axis of cell polarity, and the division remains asymmetric. spn-4 also is required for other developmental processes, including the specification of mesendoderm, the restriction of mesectoderm fate to P(1) descendants, and germline quiescence during embryogenesis. We suggest that SPN-4 post-transcriptionally regulates the expression of multiple developmental regulators. Such SPN-4 targets might then act more specifically to generate a subset of the anterior-posterior asymmetries initially specified after fertilization by the more generally required PAR and PKC-3 proteins.

Amino Acid Motifs↗
PubMed2000

The aurora-related kinase AIR-2 recruits ZEN-4/CeMKLP1 to the mitotic spindle at metaphase and is required for cytokinesis.

BACKGROUND: The Aurora/Ipl1p-related kinase AIR-2 is required for mitotic chromosome segregation and cytokinesis in early Caenorhabditis elegans embryos. Previous studies have relied on non-conditional mutations or RNA-mediated interference (RNAi) to inactivate AIR-2. It has therefore not been possible to determine whether AIR-2 functions directly in cytokinesis or if the cleavage defect results indirectly from the failure to segregate DNA. One intriguing hypothesis is that AIR-2 acts to localize the mitotic kinesin-like protein ZEN-4 (also known as CeMKLP1), which later functions in cytokinesis. RESULTS: Using conditional alleles, we established that AIR-2 is required at metaphase or early anaphase for normal segregation of chromosomes, localization of ZEN-4, and cytokinesis. ZEN-4 is first required late in cytokinesis, and also functions to maintain cell separation through much of the subsequent interphase. DNA segregation defects alone were not sufficient to disrupt cytokinesis in other mutants, suggesting that AIR-2 acts specifically during cytokinesis through ZEN-4. AIR-2 and ZEN-4 shared similar genetic interactions with the formin homology (FH) protein CYK-1, suggesting that AIR-2 and ZEN-4 function in a single pathway, in parallel to a contractile ring pathway that includes CYK-1. Using in vitro co-immunoprecipitation experiments, we found that AIR-2 and ZEN-4 interact directly. CONCLUSIONS: AIR-2 has two functions during mitosis: one in chromosome segregation, and a second, independent function in cytokinesis through ZEN-4. AIR-2 and ZEN-4 may act in parallel to a second pathway that includes CYK-1.

Animals↗
PubMed1999

The nonmuscle myosin regulatory light chain gene mlc-4 is required for cytokinesis, anterior-posterior polarity, and body morphology during Caenorhabditis elegans embryogenesis.

Using RNA-mediated genetic interference in a phenotypic screen, we identified a conserved nonmuscle myosin II regulatory light chain gene in Caenorhabditis elegans, which we name mlc-4. Maternally supplied mlc-4 function is required for cytokinesis during both meiosis and mitosis and for establishment of anterior-posterior (a-p) asymmetries after fertilization. Reducing the function of mlc-4 or nmy-2, a nonmuscle myosin II gene, also leads to a loss of polarized cytoplasmic flow in the C. elegans zygote, supporting models in which cytoplasmic flow may be required to establish a-p differences. Germline P granule localization at the time of cytoplasmic flow is also lost in these embryos, although P granules do become localized to the posterior pole after the first mitosis. This result suggests that a mechanism other than cytoplasmic flow or mlc-4/nmy-2 activity can generate some a-p asymmetries in the C. elegans zygote. By isolating a deletion allele, we show that removing zygotic mlc-4 function results in an elongation phenotype during embryogenesis. An mlc-4/green fluorescent protein transgene is expressed in lateral rows of hypodermal cells and these cells fail to properly change shape in mlc-4 mutant animals during elongation.

Animals↗
PubMed1999

MAP kinase and Wnt pathways converge to downregulate an HMG-domain repressor in Caenorhabditis elegans.

The signalling protein Wnt regulates transcription factors containing high-mobility-group (HMG) domains to direct decisions on cell fate during animal development. In Caenorhabditis elegans, the HMG-domain-containing repressor POP-1 distinguishes the fates of anterior daughter cells from their posterior sisters throughout development, and Wnt signalling downregulates POP-1 activity in one posterior daughter cell called E. Here we show that the genes mom-4 and lit-1 are also required to downregulate POP-1, not only in E but also in other posterior daughter cells. Consistent with action in a common pathway, mom-4 and lit-1 exhibit similar mutant phenotypes and encode components of the mitogen-activated protein kinase (MAPK) pathway that are homologous to vertebrate transforming-growth-factor-beta-activated kinase (TAK1) and NEMO-like kinase (NLK), respectively. Furthermore, MOM-4 and TAK1 bind related proteins that promote their kinase activities. We conclude that a MAPK-related pathway cooperates with Wnt signal transduction to downregulate POP-1 activity. These functions are likely to be conserved in vertebrates, as TAK1 and NLK can downregulate HMG-domain-containing proteins related to POP-1.

Adaptor Proteins, Signal Transducing↗
PubMed1998

cyk-1: a C. elegans FH gene required for a late step in embryonic cytokinesis.

A maternally expressed Caenorhabditis elegans gene called cyk-1 is required for polar body extrusion during meiosis and for a late step in cytokinesis during embryonic mitosis. Other microfilament- and microtubule-dependent processes appear normal in cyk-1 mutant embryos, indicating that cyk-1 regulates a specific subset of cytoskeletal functions. Because cytokinesis initiates normally and cleavage furrows ingress extensively in cyk-1 mutant embryos, we propose that the wild-type cyk-1 gene is required for a late step in cytokinesis. Cleavage furrows regress after completion of mitosis in cyk-1 mutants, leaving multiple nuclei in a single cell. Positional cloning and sequence analysis of the cyk-1 gene reveal that it encodes an FH protein, a newly defined family of proteins that appear to interact with the cytoskeleton during cytokinesis and in the regulation of cell polarity. Consistent with cyk-1 function being required for a late step in embryonic cytokinesis, we show that the CYK-1 protein co-localizes with actin microfilaments as a ring at the leading edge of the cleavage furrow, but only after extensive furrow ingression. We discuss our findings in the context of other studies suggesting that FH genes in yeast and insects function early in cytokinesis to assemble a cleavage furrow.

Actin Cytoskeleton↗
PubMed1998

Cognitive-behavioral self-help for binge eating disorder: a controlled effectiveness study.

The aim of this study was to evaluate the effectiveness of 2 methods of administering a cognitive-behavioral self-help program for binge eating disorder. The study was designed to reproduce many of the conditions that apply in settings in which self-help interventions are most relevant. Seventy-two women with binge eating disorder were randomly assigned to 1 of 3 conditions for 12 weeks: pure self-help (PSH), guided self-help (GSH), or a waiting list (WL) control condition (followed by PSH or GSH). They were then followed up for 6 months. Both PSH and GSH had a substantial and sustained impact with almost half the participants ceasing to binge eat. There was little change in the WL condition. Cognitive-behavioral self-help may be of value both as an initial treatment for binge eating disorder and as a form of secondary prevention.

Adult↗
PubMed1997

Wnt signaling polarizes an early C. elegans blastomere to distinguish endoderm from mesoderm.

A polarizing signal induces endoderm production by a 4-cell stage blastomere in C. elegans called EMS. We identified 16 mutations in five genes, mom-1 through mom-5, required for EMS to produce endoderm. mom-1, mom-2, and mom-3 are required in the signaling cell, P2, while mom-4 is required in EMS. P2 signaling downregulates an HMG domain protein, POP-1, in one EMS daughter. The sequence of mom-2 predicts that it encodes a member of the Wnt family of secreted glycoproteins, which in other systems activate HMG domain proteins. Defective mitotic spindle orientations in mom mutant embryos indicate that Wnt signaling influences cytoskeletal polarity in blastomeres throughout the early embryo.

Alleles↗
PubMed1997

Primary prevention of eating disorders: might it do more harm than good?

OBJECTIVE: The aim of this pilot study was to evaluate a new school-based eating disorder prevention program designed to reduce dietary restraint. METHOD: Forty-six school-girls, aged 13-14 years, took part. The intervention consisted of eight weekly sessions of 45 min duration. A battery of self-report questionnaires was administered before and after the intervention and 6 months later. RESULTS: Unlike previous prevention studies, there was not only an increase in knowledge at postintervention but there was also a decrease in target behavior and attitudes. However, these effects were short-lived since they had disappeared 6 months later: indeed, at 6-month follow-up there was an increase in dietary restraint compared with baseline. DISCUSSION: These findings suggest that the intervention had been counterproductive since it led to an increase in dietary restraint. They imply that school-based prevention programs may do more harm than good.

Adolescent↗
PubMed1984

Hemispheric asymmetry of EEG alpha activation: effects of gender and familial handedness.

Twenty-four male and twenty-four female undergraduates took part in an experiment to investigate the effects of gender and familial handedness on hemispheric activation during numeric and visuospatial thinking. Each gender group was divided into twelve subjects with close left handed relatives and twelve subjects without. All subjects were overtly right handed. EEG alpha activity was recorded from left and right occipital and parietal regions with respect to mastoid references while the subjects performed numeric tasks with eyes open and with eyes closed, a face-recognition and a tactile-discrimination (figural-unification) task. EEG alpha power was quantified during these conditions and during relaxed wakefulness with eyes open and eyes closed. Relative activation, (suppression of alpha activity from rest) of left and right parietal regions during numeric and spatial tasks was found to depend upon gender and familial handedness. Males, not females, tended to switch from left hemisphere activation during face recognition. Irrespective of gender and to some extent of task, a tendency towards greater activation of the right hemisphere was associated with the possession of left handers among close relatives.

Adolescent↗