Biomedical subjects

I M Evans

Publications and source records attributed to I M Evans.

At least 19 recordsLinked to original sources

PubMed2003

Maternal hypothyroidism in the rat influences placental and liver glycogen stores: fetal growth retardation near term is unrelated to maternal and placental glucose metabolic compromise.

Maternal hypothyroidism impairs fetal growth in the rat, but the mechanisms by which this occurs are unknown. Since the fetus derives its glucose supply from the mother, and maternal thyroidectomy may disturb maternal and placental glucose metabolism, we postulated that maternal and/or placental glucose metabolic compromise may contribute to fetal growth retardation in hypothyroid dams. Feto-placental growth, tissue glycogen stores and glucose levels in sera and amniotic fluid were determined in rat dams partially thyroidectomized (TX) before pregnancy and in euthyroid controls. Fetal body weight at 16, 19 and 21 days gestation (d.g.) was related to pre-mating maternal serum total thyroxine (TT(4)) levels; permanent fetal growth retardation occurred in severely (TX(s); pre-mating maternal serum TT(4)<or=16.19 nM) - but not in moderately (TX(m)) - hypothyroid dams. In TX(s) dams, glycogen concentration was elevated in maternal liver and in the fetal side of the placenta at 16 and 19 d.g., and in the maternal side of the placenta at 19 and 21 d.g., despite maternal euglycemia. In contrast, fetal liver glycogen concentration was deficient in TX(m) dams at 19 d.g. and in TX(s) dams at 19 and 21 d.g., and fetal hypoglycemia occurred in TX(s) dams at 21 d.g. Multiple regression analyses indicate that these fetal deficits are strongly associated with the retardation in fetal growth, while the elevated maternal liver and placental glycogen concentrations have no impact on fetal growth near term. The mechanisms by which severe maternal hypothyroidism permanently retards rat fetal growth remain to be determined.

Amniotic Fluid↗

PubMed2002

Influence of maternal hyperthyroidism in the rat on the expression of neuronal and astrocytic cytoskeletal proteins in fetal brain.

Maternal hypothyroidism during pregnancy impairs brain function in human and rat offspring, but little is known regarding the influence of maternal hyperthyroidism on neurodevelopment. We have previously shown that the expression of neuronal and glial differentiation markers in fetal brain is compromised in hypothyroid rat dam pregnancies and have now therefore extended this investigation to hyperthyroid rat dams. Study groups comprised partially thyroidectomised dams, implanted with osmotic pumps infusing either vehicle (TX dams) or a supraphysiological dose of thyroxine (T4) (HYPER dams), and euthyroid dams infused with vehicle (N dams). Cytoskeletal protein abundance was determined in fetal brain at 21 days of gestation by immunoblot analysis. Relative to N dams, circulating total T4 levels were reduced to around one-third in TX dams but were doubled in HYPER dams. Fetal brain weight was increased in HYPER dams, whereas litter size and fetal body weight were reduced in TX dams. Glial fibrillary acidic protein expression was similar in HYPER and TX dams, being reduced in both cases relative to N dams. alpha-Internexin (INX) abundance was reduced in HYPER dams and increased in TX dams, whereas neurofilament 68 (NF68) exhibited increased abundance in HYPER dams. Furthermore, INX was inversely related to - and NF68 directly related to - maternal serum total T4 levels, independently of fetal brain weight. In conclusion, maternal hyperthyroidism compromises the expression of neuronal cytoskeletal proteins in late fetal brain, suggestive of a pattern of accelerated neuronal differentiation.

Analysis of Variance↗

PubMed2001

Coping and catastrophizing in chronic pain: a psychometric analysis and comparison of two measures.

We analyzed and compared the psychometric properties of two measures of strategiesfor coping with pain:The Coping Strategies Questionnaire (CSQ) and the Cognitive Coping Strategies Inventory (CCSI). The CSQ and CCSI were repeatedly administered to 30 chronic pain patients. Several subscales of both measures showed inadequate internal consistency, and test-retest (one week interval) reliability lower than 0.7. For each inventory, moderate to strong intercorrelations between several subscales were observed. The Catastrophizing subscale was the only subscale for which there was clear evidence of construct validity. Results indicated that both measures showed similar psychometric difficulties, and question the construct validity of subscales other than Catastrophizing. Catastrophizing, however, more closely reflects appraisal processes than a coping strategy per se. We suggest that measures that use more parsimonious and empirically derived coping strategy subscales and that also assess appraisal factors would assist in advancing our understanding of coping with chronic pain.

Adaptation, Psychological↗

PubMed2001

The underlying psychopathology of eating disorders and social phobia: a structural equation analysis.

This study investigates the underlying psychopathology of disordered eating and social phobia behaviours by examining the interrelationships between variables thought to be common to both. The participants were 252 female tertiary students. Each completed measures of eating behaviours, social phobia, body esteem, fear of negative evaluation, social support, self-acceptance, and general psychopathology. Structural equation modelling was used to determine if fear of negative evaluation and social support had a direct or indirect effect on the behaviours of disordered eating, social phobia, and body esteem. Findings indicated that fear of negative evaluation had a direct and indirect effect on the behaviours associated with eating disorders and social phobia, and only an indirect effect on body esteem. Social support indirectly affected eating disorders, social phobia, and body esteem. Implications from this study are that social support, fears of being criticised or rejected by others, and low self-acceptance are important variables in the assessment of eating disorders and social phobia.

Journal Article↗

PubMed2001

Thyroid hormone receptor expression in rat placenta.

The expression of c- erbAalpha and -beta encoded thyroid hormone receptors (TR) was investigated in rat placenta between 16 and 21 days of gestation (dg), and in fetal liver and brain at 16 dg, using semi-quantitative RT-PCR and nuclear 3,5,3'-triiodothyronine (T(3)) binding. TRalpha1, TRbeta1, c- erbAalpha 2 and c- erbAalpha 3 mRNA abundance was unchanged in placenta between 16 and 21 dg, as was the dissociation constant (K(d)) of T(3) binding. The maximal T(3) binding capacity (B(max)) in placenta doubled over this period, suggesting placental TR binding activity is post-transcriptionally regulated. Transcript abundance in tissues at 16 dg can be summarized: TRalpha1, placenta=fetal liver fetal brain; c- erbAalpha 2 and alpha3, placenta=fetal liver<fetal brain; TRbeta2; none detected. T(3)binding in fetal liver and brain exhibited equivalent K(d) and B(max), the K(d) being less than 50 per cent of that in placenta, though B(max) was unchanged. The higher K(d)in placenta may reflect tissue-specific patterns of TR modification. In conclusion, rat placenta expresses significant levels of c- erbAalpha and -beta transcripts and protein, providing a possible mechanism of action for T(3) of maternal and fetal origin in this tissue.

Animals↗

PubMed2001

Children's perceptions of unfair reward and punishment.

Being able to judge the fairness of a personal encounter and having an appreciation of the associated feelings are important components of prosocial development. This study explored a common feature of everyday experience: unfair reward and unfair punishment. Scenarios depicting 4 possible variants of unfairness were read to children aged 9 to 11 years, who then made judgments regarding the degree of unfairness and the nature and strength of the feelings experienced by the characters. Our hypothesis that children with classroom conduct problems would judge the non-receipt of a deserved reward as worse than the receipt of an undeserved punishment was not confirmed. This differentiation, however, did prove to be characteristic of boys in general, but not girls. Being asked to think of unfair things that had actually happened did not appear to influence the children's responses to hypothetical unfair situations, but did reveal that children experience and remember a variety of unfair events in everyday family contexts. This study provides evidence that children actively monitor the receipt of social reward and punishment according to their perception of fairness.

Awards and Prizes↗

PubMed2000

Risk factors for a New Zealand sample of sexually abusive children and adolescents.

OBJECTIVE: The aim was to understand variables contributing to the occurrence of sexual offending in children and adolescents. METHOD: Twenty youngsters who had engaged in coercive sexual behavior involving other children were compared to a matched group of clinic-referred youngsters with conduct disorders. Assessments included family histories, interviews, and psychometric measures. RESULTS: There was no group difference in the frequency of experiencing sexual abuse. However, sexually abusive youngsters were more often exposed to adult caregivers with known histories of being sexually abusive. These children had been subjected to multiple distortions of adult attachment, tended to internalize distress, and failed to use available social supports. They were likely to have experienced physical and verbal abuse; children with behavior disorders were more likely to have a parent with a psychiatric illness and to have experienced parental conflict. CONCLUSION: Severely disrupted attachment, in conjunction with family experiences of inappropriate sexual expression, place children and adolescents at risk for sexual offending. Sexually abusive youngsters had less social supports and their offending occurred after a negative emotional experience, when there was opportunity in the form of younger victims. The study suggests an interaction among developmental pathways, coping skills, and immediate proximal variables for the perpetration of sexual abuse by young people.

Adolescent↗

PubMed2000

Defining effective community support for long-term psychiatric patients according to behavioural principles.

OBJECTIVE: The purpose of this article is to define the characteristics of effective support in community mental health settings for patients with serious and persistent mental illness. METHOD: A broad literature providing empirical evidence on competent caregiver behaviours and styles is selectively reviewed. Relevant findings from family caregiver research and studies of social environments that enhance skill development in people with intellectual disabilities are incorporated, within a cognitive-behavioural framework. RESULTS: Six important domains are identified which represent positive caregiver styles: acceptance, creating a positive atmosphere, expectations of change, responsiveness, normalisation and educativeness. CONCLUSION: The characteristics hypothesised to be critical for caregivers and support workers are defined in a general way that can allow for individualisation according to the goals of the programs and the cultural priorities of staff and patients. Further empirical validation of these characteristics would enable community mental health services to provide more specialised clinical treatments.

Cognitive Behavioral Therapy↗

PubMed2000

Maternal thyroid status regulates the expression of neuronal and astrocytic cytoskeletal proteins in the fetal brain.

Maternal thyroid hormone (TH) crosses the placenta and is postulated to regulate fetal brain development. However, TH-dependent stages of fetal brain development remain to be characterised. We have therefore compared the levels of several neuronal and glial cytoskeletal proteins in fetal brains from normal (N) and partially thyroidectomised (TX) rat dams by immunoblotting. Pregnancies were studied both before and after the onset of fetal TH secretion, which occurs at 17.5 days gestation (dg) in the rat. Maternal hypothyroidism disrupted fetal growth, so that fetal body and brain weights were reduced near term. Vimentin expression was unaffected, however, indicating normal acquisition of neuronal and glial precursor cells. Fetal brain levels of glial fibrillary acidic protein (GFAP) were reduced at 21 dg, suggesting delayed astrocytic differentiation, although regression analysis demonstrated appropriate GFAP levels for brain weight. Levels of alpha-internexin, the earliest neurofilament protein expressed in fetal brain were reduced at 16 dg in TX dams, but increased at 21 dg. The ontogeny of neurofilament-L was also perturbed in these pregnancies, with deficient levels apparent at both 16 and 21 dg. These effects on neuronal cytoskeletal proteins were unrelated to fetal brain growth retardation. These findings confirm that maternal hypothyroidism disrupts early fetal brain development. Early disturbances in neuronal differentiation are not corrected by the onset of fetal TH secretion. Such disturbances may contribute to the neurological damage observed in children born to hypothyroxinaemic mothers.

Analysis of Variance↗

PubMed1999

SHORT COMMUNICATION maternal thyroid dysfunction and c- fos and c- jun expression in rat placenta.

Maternal thyroid dysfunction is associated with perturbed fetal brain development and neurological deficits in adulthood in rat and human. To investigate whether these effects occur secondary to placental dysfunction, c- fos and c- jun expression in placenta from normal (euthyroid) and moderately hypothyroid rat dams were investigated by Northern hybridization analysis. In normal placenta, c- fos expression increased by 74 per cent between 16 and 21 days of gestation (dg) whereas c- jun expression declined by 46 per cent. Moderate maternal hypothyroidism depressed placental c- fos expression by 32 per cent at 19 dg, but elevated c- fos and c- jun expression by 139 and 86 per cent, respectively, at 21 dg. Maternal hypothyroidism may therefore induce c- fos/c- jun -related placental dysfunction, but only relatively late in gestation when fetal thyroid function is already established.

Animals↗

PubMed1999

Child-focused behavioral assessment and modification.

Argues that behavioral principles have been translated into practice with children too literally and that a more integrative framework is required to guide assessment and treatment. The framework advocated is Staats's (1996) psychological behaviorism. This is a consistently behavioristic, positivist paradigm, using multilevel theory to emphasize the integration of social learning, developmental, and personality principles. Psychological behaviorism thus allows for a much more expansive approach than has typically been the case within child behavior therapy. Given the complexity of this perspective, I selected four broad tenets of the theory and suggested their implications for clinical contexts. The further translation from clinical models to specific clinical practices is quite difficult but may yield more flexible and substitutable practices than do unidimensional treatment outcome studies. Of special importance, the principles demonstrate how children themselves can retain the central focus of child behavioral assessment and modification. Specific practices still need to be constructed according to an understanding of the multiple sources of influence on children as well as the culture of childhood itself.

Behavior Therapy↗

PubMed1999

Maternal hypothyroxinemia disrupts neurotransmitter metabolic enzymes in developing brain.

Maternal thyroid status influences early brain development and, consequently, cognitive and motor function in humans and rats. The biochemical targets of maternal thyroid hormone (TH) action in fetal brain remain poorly defined. A partially thyroidectomized rat dam model was therefore used to investigate the influence of maternal hypothyroxinemia on the specific activities of cholinergic and monoaminergic neurotransmitter metabolic enzymes in the developing brain. Maternal hypothyroxinemia was associated with reduced monoamine oxidase (MAO) activity in fetal whole brain at 16 and 19 days gestation (dg). A similar trend was observed for choline acetyltransferase (ChAT) activity. In contrast, DOPA decarboxylase (DDC) activity was markedly elevated at 21 dg. Further study of these enzymes at 14 dg showed no differences between normal and experimental progeny - suggesting they become TH sensitive after this age. Tyrosine hydroxylase (TyrH) and acetylcholinesterase (AChE) activities were unaffected prenatally. During postnatal development, the activities of TyrH, MAO, DDC and, to a lesser extent, AChE were increased in a brain region- and age-specific manner in experimental progeny. The prenatal disturbances noted in this study may have wide-ranging consequences since they occur when neurotransmitters have putative neurotropic roles in brain development. Furthermore, the chronic disturbances in enzyme activity observed during postnatal life may affect neurotransmission, thereby contributing to the behavioural dysfunction seen in adult progeny of hypothyroxinemic dams.

Aging↗

PubMed1996

Individualizing therapy, customizing clinical science.

The focus of this paper is to propose that the question of standardized versus individualized therapy is part of a more general debate regarding the nature of inquiry, the use of empirical knowledge in practice, and the evaluation of professional activities-what collectively might be called clinical science. Exclusive reliance on traditional experimental research design, with its demand for procedural standardization, promotes a model of clinical behavior therapy as a technology. Such a perspective runs counter to the development of the special relationship between theory (generality) and practice (specificity) that represents one of behavior therapy's unique contributions and long term legacies. If behavior therapists treating individual clients are to adapt general principles to individual need, there must be a broader view of relevant sources of individual differences.

Behavior Therapy↗

PubMed1994

A homologue of the 65 kDa regulatory subunit of protein phosphatase 2A in early pea (Pisum sativum L.) embryos.

A partial cDNA, isolated from an early developing pea (Pisum sativum L.) embryo library, was found to encode a plant homologue of the regulatory subunit (PR65) of protein phosphatase 2A (PP2A). Comparison of the deduced amino acid sequence with a human PR65 sequence showed that the regulatory subunit of PP2A has been highly conserved during evolution. Southern analysis demonstrated that in pea and rape the catalytic and regulatory subunits of PP2A are encoded by multigene families. The levels of the transcripts encoding each subunit are developmentally regulated during pea embryogenesis and expression of the regulatory subunit is not solely restricted to the embryo.

Amino Acid Sequence↗

PubMed1994

Characterisation of cDNA and genomic clones encoding homologues of the 65 kDa regulatory subunit of protein phosphatase 2A in Arabidopsis thaliana.

Two cDNA species encoding sequences homologous to the 65 kDa regulatory subunit (PR 65) of protein phosphatase 2A (PP2A) have been isolated from an Arabidopsis thaliana cDNA library. These were designated pDF1 and pDF2. pDF1 is 1795 bp long and by comparison with the human and porcine PP2A regulatory subunit sequences represents a full-length clone. It encodes a predicted polypeptide of 587 amino acid residues. pDF2 is truncated at the 5' end by 237 bp. The complete nucleotide sequences have been determined for both cDNA species. Comparison of the nucleotide and the deduced amino acid sequences showed that the two sequences were homologous but not identical and therefore must be derived from two different genes. Northern blot analysis was performed on total RNA and poly(A)+ RNA isolated from seed at various stages of development and from young leaf material of Brassica napus L. (oilseed rape). Both cDNA probes hybridised to a single major mRNA species of ca. 2.2 kb. The highest level of expression was observed in the total RNA from developing rape seed at about 33 days after flowering, and the transcript level in the poly(A)+ RNA of the seed was higher than in young leaf of oilseed rape. Southern blot analysis was performed on two varieties of A. thaliana and B. napus genomic DNA; this identified a small family of genes in A. thaliana consisting of at least 2 or 3 members and a larger multigene family in B. napus of at least 5 or 6 members. Two independent genomic clones were isolated from an A. thaliana genomic library. Sequencing of a fragment common to both revealed that the sequence was identical in both clones and, therefore, they were assumed to contain the same genomic sequence. The genomic sequence selected, designated regA, is 3639 bp long and the coding sequence contains eleven introns. The gene encodes a predicted polypeptide of 590 amino acid residues. The sequence comparison with both cDNA sequences showed that it is homologous but not identical to the two, confirming that at least three different genes exist in A. thaliana which encode PR65 of PP2A.

Amino Acid Sequence↗

PubMed1994

The effects of training in nonaversive behavior management on the attitudes and understanding of direct care staff.

Recent developments in behavior therapy for persons with developmental disabilities and behavior disorders emphasize positive treatment designs that focus on understanding the causes of behavior, teaching functional alternatives, and enhancing the quality of daily experiences, rather than simple contingency management. There is little information on how well direct care staff can support these nonaversive strategies. This study examined the effects of training in traditional (positive) behavior management versus nonaversive principles on the understanding and attitudes of direct care staff. Overall, nonprofessional level staff receiving the nonaversive training showed increased sophistication in understanding the range of possible causes of behavior and were able to generate treatment suggestions based on skill development and environmental change. The effectiveness of staff in implementing state-of-the-art behavior therapy procedures is likely to be an important component of the continued success of behavior therapy, especially in residential settings, both institutional and community-based.

Adult↗

PubMed1994

Affective reactivity of language in schizophrenia.

Thirty acutely schizophrenic inpatients each provided two speech samples: one on affectively negative, "high-stress" topics and one on affectively positive, "low-stress" topics. We analyzed these using two different, established methods for assessment of deviance in natural language, including clinical measures of thought disorder and linguistic measures of reference performance. For the group as a whole, the speech on negative topics contained more disorder than did the speech on positive topics, as rated both clinically and linguistically, and these differences were sizeable and highly significant. Level of language disturbance and degree of affective reactivity of language symptoms correlated positively with severity of the positive syndrome but were not associated in either direction with negative syndrome severity. Affective reactivity of symptoms is discussed as a variable potentially relevant to studies of psychophysiology and subtyping in schizophrenia.

Adult↗

PubMed1994

Transport of thyroid hormones to target tissues.

Endemic iodine deficiency is associated with maternal hypothyroxinemia and a relatively high incidence of neurological disorders in the offspring. The previous assumption that the placenta is impermeable to maternal thyroid hormone, has resulted in the erroneous suggestion that iodine per se has an essential role in brain development. Furthermore, the observed factorial rise in thyroxine-binding globulin (TBG) in pregnancy has often been misinterpreted as preventing thyroid hormone loss to either the fetal compartment or excretory systems. However, physiochemical analysis of the role of specific binding proteins in hormone delivery, combined with epidemiological evidence and evolutionary considerations has led us to postulate that a) maternal thyroxine (T4) is transported to the fetus, and is of crucial importance in early fetal development, and b) TBG forms part of a control system specifically designed to maintain at an optimal level the T4 environment to which the developing fetus is exposed. Placental transfer of maternal T4 in a variety of mammalian species (including humans) is now well established. Further experimental studies in rats have shown that perturbation of the intrauterine thyroid hormone environment during critical phases of brain development results in a spectrum of biochemical dysgenesis. For example, in fetal brains deriving from hypothyroxinemic (Tx) rat dams, severe disruption of phosphate metabolism is observed and the ontogenesis of two enzyme activities associated with growth control, protein kinase C and ornithine decarboxylase, are compromised. Development of brain function is also impaired, as evidenced by the dysgenesis of certain neurotransmitter metabolic activities (choline acetyltransferase and DOPA decarboxylase).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗