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Biomedical subjects

G W Stuart

Publications and source records attributed to G W Stuart.

At least 19 recordsLinked to original sources
PubMed1992

Positive and negative symptoms in the psychoses: multidimensional scaling of SAPS and SANS items.

Recently, the validity of the simple dichotomy between positive and negative symptoms in psychosis has been questioned. A newly admitted group of 114 DSM-III patients with psychotic disorder were assessed using Andreason's positive and negative symptoms scales. Multidimensional scaling, augmented by cluster analysis, was applied to the full item set of these scales and showed clearly that there are three major, independent groups of symptoms: Hallucinations/Delusions, Positive Thought Disorder and Negative Symptoms. Within the Hallucinations/Delusions and Negative Symptoms groups there was some additional structure which does not conform to the SAPS and SANS sub-scales. In particular there was considerable heterogeneity within the Hallucinations/Delusions group, and delusions of persecution may represent a fourth independent dimension of psychopathology which is under-represented in these scales.

Adult↗
PubMed1992

Cooperative representation of visual borders.

Recently it has been reported that the visual cortical cells which are engaged in cooperative coding of global stimulus features, display synchrony in their firing rates when both are stimulated. Alternative models identify global stimulus features with the course spatial scales of the image. Versions of the Munsterberg or Café Wall illusions which differ in their low spatial frequency content were used to show that in all cases it was the high spatial frequencies in the image which determined the strength and direction of these illusions. Since cells responsive to high spatial frequencies have small receptive fields, cooperative coding must be involved in the representation of long borders in the image.

Attention↗
PubMed1992

Colour inputs to random-dot stereopsis.

Recently it has been claimed by Livingstone and Hubel that, of three anatomically and functionally distinct visual channels (the magnocellular, parvocellular interblob, and blob channels), only the magnocellular channel is involved in the processing of stereoscopic depth. Since the magnocellular system shows little overt colour opponency, the reported loss of the ability to resolve random-dot stereograms defined only by colour contrast seems consistent with this view. However, Julesz observed that reversed-contrast stereograms could be fused if correlated colour information was added. In the present study, 'noise' (non-corresponding) pixels were injected into random-dot stereograms in order to increase fusion time. All six subjects tested were able to achieve stereopsis in less than three minutes when there was only correspondence in colour and not in luminance, and three when luminance contrast was completely reversed. This ability depends on information about the direction of colour contrast, not just the presence of chromatic borders. When luminance and chromatic contrast are defined in terms of signal-to-noise ratios at the photoreceptor mosaic, chromatic information plays at least as important a role in stereopsis as does luminance information, suggesting that the magnocellular channel is not uniquely involved.

Color Perception↗
PubMed1992

Visual processing deficits in dyslexia: receptors or neural mechanisms?

In 1989 and 1990 Grosser and Spafford attributed abnormalities in the peripheral vision of dyslexic subjects to an anomalous distribution of rods and cones. We argue that at the light levels used in these experiments cone responses should dominate both central and peripheral vision. A more likely explanation of their findings is that there is a postreceptoral deficit in the transient visual channel. This hypothesis is supported by independent anatomical, physiological, and psychophysical evidence.

Attention↗
PubMed1992

The effects of pregnancy on preexisting panic disorder.

BACKGROUND: Limited evidence suggests that pregnancy may be associated with a reduction of panic and related symptoms. The authors investigate reported changes in panic symptoms during pregnancy. METHOD: Questionnaires asking about changes in panic and phobic avoidance symptoms during pregnancy were mailed to 129 women who had previously participated in our Anxiety Disorders Program over a 5-year period; all had diagnoses of panic disorder by DSM-III-R criteria. Reported here are responses from 22 of the women who experienced pregnancy after the onset of panic disorder. RESULTS: A majority of women (14 of 22) reported a decrease in panic symptoms during pregnancy, but significant variability in this phenomenon occurs between and within individuals. CONCLUSION: A subpopulation of women may experience improvement in panic symptoms during pregnancy, which has implications for management of these patients. Further research is needed to verify the existence of such a subpopulation and to determine an etiology.

Agoraphobia↗
PubMed1991

Concordance with recommendations in a consultation-liaison psychiatry service.

We studied the concordance of physicians with the recommendations of psychiatric consultants in a sample of 270 consultations in a 400-bed general hospital. Of the patients about whom a consultation was sought, 37% had a past psychiatric history, and 67% were on psychotropic drugs. Twelve percent had Organic Mental Disorder, 35% Affective Disorder, and for 24% no DSM-III diagnosis could be made. The psychiatrist made psychotropic drug recommendations in 62%, and the physicians' concordance with this recommendation was 86%. The physician's discharge summary included a diagnosis which concorded with the psychiatrist's diagnosis in 53% of files. The psychiatrist recommended further investigations in only 5.2% of files.

Adolescent↗
PubMed1991

Comparison of participants and nonparticipants in a neuroendocrine investigation of psychosis.

Of all neuroleptic-naive, acutely psychotic subjects admitted to hospital over a 2-year period (n = 62), 27 participated in a neuroendocrine study and 35 did not participate (51% refused consent, 19% were incapable of consent and 31% started neuroleptics immediately). However, all nonparticipants agreed to psychopathological evaluation, thus allowing comparison between participants and nonparticipants. The 2 groups were similar in most respects, except that more nonparticipants were hostile. Among subjects with schizophrenia, 47% of nonparticipants had the paranoid subtype vs 8% of participants. There was also a trend towards longer illness duration in nonparticipants. These results underline the need for neurobiological studies of psychosis to consider sample bias as a confounding variable.

Adult↗
PubMed1991

The prevalence of psychiatric morbidity in general hospital inpatients.

The aim of this study was to examine the prevalence of psychiatric morbidity in a sample of medical and surgical inpatients in an Australian general hospital. Using the 60-item General Health Questionnaire, the estimated prevalence was 30% (previous studies have yielded estimates generally between 20 and 50%). The prevalence of morbidity was significantly higher in medical (45%) than in surgical (23%) inpatients. Twelve percent of patients (20% of medical patients and 8% of surgical patients) satisfied DSM-III criteria for a current Major Depressive Episode. Anxiety scores on the State-Trait Anxiety Inventory were higher than those reported in general population samples. There were no significant differences between males and females on any scores. The problems associated with the definition and identification of depressive and anxiety syndromes in medical and surgical inpatients are discussed, whilst the importance of this task is emphasized.

Anxiety Disorders↗
PubMed1991

The Fraser illusion: complex figures.

The cause of the Fraser illusion, which occurs when a line made up of tilted segments itself appears tilted, is examined further. In this series of experiments, we used figures that resembled the original Fraser illusion; they were more complex than those reported on in our previous paper (Stuart & Day, 1988). The figures were used to explore two theories of the Fraser illusion further: that it is the result of interactions between orientation selective units, and that it is a consequence of the local, distributed processing of orientation. The presence of background elements like those used in the original illusion led to an increase in the strength of the illusion, but the shape of these elements had no differential effect on illusion strength. There was a differential effect of the background on the assimilative and contrast illusions, owing respectively to small and large tilts of the inducing elements. The illusion was markedly reduced at small visual angles when the background was absent, but it was only slightly affected when the background was present. All these findings are difficult to explain in terms of interactions between single units, either at the same or at different scales in the image. The effects of luminance contrast and isoluminance on the illusion were not consistent with either theory, but they indicated that researchers need to consider the role of figure-ground organization in this illusion.

Adolescent↗
PubMed1991

Nursing care in electroconvulsive therapy.

Psychiatric nursing care for the electroconvulsive therapy (ECT) patient has evolved from a traditional supportive and adjunctive practice to the current practice of independent and collaborative nursing actions. The nurse's multifaceted role is enacted by providing education and support, performing pretreatment assessments, monitoring the procedure, and observing and interpreting posttreatment patient responses. Areas of future nursing education and research should include the expansion of nursing practice with the ECT patient in the provision of quality nursing care.

Electroconvulsive Therapy↗
PubMed1990

Dilemmas and directions for psychiatric nursing in the 1990s.

Problems with the recruitment of nurses to the specialty area of psychiatric nursing have stimulated much debate and discussion in the field. This article explores dimensions of psychiatric nursing education, science, and practice and their impact on the future of this specialty area of nursing. It proposes that the present task is to define more precisely the continuum of psychiatric mental health nursing both to differentiate between psychosocial (mental health) and psychiatric (mental illness) components of the role and balance the priority that psychiatric nurses give to each in educational curricula, research agendas, and practice settings.

Curriculum↗
PubMed1990

Early family experiences of women with bulimia and depression.

This study characterizes the early family experiences of 30 women with bulimia nervosa and 15 women with major depression, and compares them with 100 women controls, with particular emphasis placed on parental rearing practices, family conflict resolution, sexual mistreatment, problematic childhood indicators, and childhood separation experiences. There is little research on these patient populations in relation to their childhood experiences, and thus, it is difficult to identify markers for women at risk for these disorders. The findings show that there are significant differences between the experiences these women had growing up and those of the control group, and a profile of children at risk based upon the study indicators is presented.

Bulimia↗
PubMed1990

CSF monoamine levels in normal-weight bulimia: evidence for abnormal noradrenergic activity.

Normal-weight bulimic patients have disturbed appetite, mood, and neuroendocrine function and often respond to antidepressants. Since these findings suggest abnormalities in brain monoaminergic pathways, the authors measured CSF monoamine concentrations in 27 normal-weight bulimic patients and 14 volunteers. Bulimic patients had a significantly lower mean CSF norepinephrine concentration. Levels of CSF 5-HIAA, the major serotonin metabolite, and CSF HVA, the major dopamine metabolite, were normal, although more frequent binge-eating in bulimic subjects was associated with a significantly lower CSF HVA level. Whether trait- or state-related, monoaminergic disturbances are part of this disorder's neurobiological syndrome. The lower CSF norepinephrine concentration suggests bulimia is not simply a variant of affective disorders.

Adult↗
PubMed1990

Stable lines of transgenic zebrafish exhibit reproducible patterns of transgene expression.

To study the frequency of germ-line transformation and to examine the reproducibility of tissue-specific transgene expression, we produced several lines of transgenic zebrafish expressing a recombinant chloramphenicol acetyltransferase (CAT) gene. Supercoiled plasmids containing both Rous sarcoma virus and SV-40 promoter sequences upstream of the CAT coding region were injected into zebrafish embryos prior to first cleavage. CAT activity could be detected in batches of injected embryos as early as 8 h and up to at least 12 days post-fertilization. Approximately 18% of injected fish raised to maturity exhibited CAT activity in their fins, and approximately 5% of injected fish became stable germ-line transformants. Breeding studies indicated that although transgenic founder fish were frequently germ-line mosaics, transgenic individuals of subsequent generations were fully hemizygous for the transgene marker. The transgenes present in the F1 progeny of four independent lines were relatively well expressed in fin and skin, while lower levels of expression were observed in heart, gill and muscle. Little or no CAT expression was observed in the brain, liver and gonad. A monoclonal antibody directed against the CAT gene product consistently revealed variegated patterns of CAT expression in ectodermally derived fin epidermal cells in three of these lines. These results show that it is possible to efficiently produce stable germ-line transformants of the zebrafish and to observe reproducible tissue-specific patterns of transgene expression in this organism. Possible mechanisms for the variegated expression observed within tissues are also considered.

Animals↗
PubMedDate not supplied

Construct validation in adolescents of the brief current form of the Parental Bonding Instrument.

We have reported elsewhere the development of a brief version of the Parental Bonding Instrument (PBI), which we have called the Parental Bonding Instrument-Brief Current form (PBI-BC), for use in survey research in adolescent samples. It was shown in that report that PBI-BC retained the factor structure of the original instrument. The structure remained stable in adolescents' ratings of their mothers and their fathers. Given the evidence of a relationship between the dimensions from the original scale and psychopathology, it was expected that the PBI-BC would be similarly related to measures of psychopathology, namely, that there would be a set of positive correlations between the perceived parental bonding styles of high control and low autonomy-giving and measures of pathology, with a negative relationship between pathology and perceived parental styles of high care and low rejection. In addition, the present study explored the relationships between perceived parental styles and bipolar positive and negative self-concept measures, with the expectations that high control and low autonomy would be associated with more negative self-concept and that high care and low rejection would be associated with more positive self-concept. The results generally confirmed these expectations, suggesting that the brief instrument has adequate construct validity and would be particularly useful as a brief index in studies of adolescents.

Acculturation↗