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Biomedical subjects

G W Stuart

Publications and source records attributed to G W Stuart.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1989

Specificity of the salivary cortisol dexamethasone suppression test across psychiatric diagnoses.

One hundred forty-eight psychiatric inpatients, 12 outpatients, and 17 normal controls were given the 1.0-mg overnight Dexamethasone Suppression Test (DST), with salivary cortisol concentrations being measured as the dependent variable. Based on the Structured Clinical Interview for DSM-III, the patients were diagnosed as having major depression with melancholia (n = 21), nonmelancholic major depression (n = 50), mania (n = 15), schizophrenia (n = 32), dementia (n = 6), substance dependence/abuse n = 18), and miscellaneous (n = 18). Neither the melancholic major depressives nor the entire group of major depressives had significantly higher salivary cortisol pre- or postdexamethasone as compared with all the other patients combined, nor did the melancholic patients have significantly higher cortisol than the nonmelancholic depressives. The inpatients as a group had significantly higher pre- and postdexamethasone cortisol values than the normal controls; cortisol values for the outpatients were intermediate between these two groups. Illness severity (in the depressives), length of time in hospital before the DST, and medication regimen were all unrelated to DST outcome. Thus, in this study, the salivary cortisol DST showed little clinical utility in discriminating major depressives with and without melancholia from other patients with a broad range of psychiatric diagnoses. The test did distinguish between hospitalized psychiatric patients and normal control subjects and between depressed inpatients and depressed outpatients, indicating that hospitalization-related variables contributed to DST outcome.

Adult↗
PubMed1989

Behavioral treatment of panic-related disorders: a review.

Behavioral theories and therapy techniques for panic-related disorders are reviewed. A variety of research studies and measurement techniques are discussed, and methodological issues are highlighted, particularly with respect to outcome measures and controversies in the literature regarding treatment assessments. The preponderance of treatments and research to date have examined the effects of various combinations of treatments on panic disorder. More recently, the use of behavioral therapy for panic disorders has received increasing empirical support. This paper describes treatments for panic-related disorders, especially phobic avoidance behavior, from a behavioral therapy context.

Behavior Therapy↗
PubMed1988

Replication, integration and stable germ-line transmission of foreign sequences injected into early zebrafish embryos.

To generate stable lines of transgenic fish, early zebrafish embryos were injected with high concentrations of a linear bacterial plasmid. After injection, the foreign DNA was converted into a high molecular weight form and then amplified approximately tenfold during the initial rapid cleavages characteristic of the early embryo prior to gastrulation. While most of this DNA was subsequently degraded during gastrulation, some of the foreign sequences survived the gastrula stage and could be found in most of the injected fish at 3 weeks of age. Only about 5% of fish analysed 4 months after the injection retained foreign DNA in their fins, usually at less than one copy per cell. One of these fish was also found to contain about 100 copies per cell of foreign DNA in a fraction of its germ cells. Approximately 20% of the F1 offspring from this germ-line-positive parent inherited the foreign DNA, whereas 50% of F2 progeny obtained from an identified F1 individual inherited these sequences. The 50% transmission rate in F2 progeny was as expected for a single, heterozygous genomic insert. These observations indicate that injected DNA can be integrated into the fish genome, that the resulting transgenic fish are mosaic and that some of these mosaic individuals give rise to stable lines of transgenic fish.

Animals↗
PubMed1987

Metal regulatory elements of the mouse metallothionein-I gene.

The promoter of the mouse metallothionein-I (mMT-I) gene contains multiple metal regulatory elements (MREs) which allow transcription of the gene to be induced by heavy metals. Insertion into the promoter of the TK gene of two or more synthetic MREs enables that gene to respond to heavy metals. We tested each of the MREs from the mMT-I promoter in this assay, and found four to be functional. We have commenced a systematic analysis of single nucleotide changes within an MRE, to determine the contribution of each nucleotide. The MRE core sequence in which single nucleotide changes can abolish function is TGCRCNCG; certain changes outside this sequence have lesser effects. MREs can act cooperatively with distal promoter elements of the TK gene, but in the presence of just a TATA-box they function as heavy-metal dependent promoter elements. Experiments to determine the effect of spacing suggest a range of at least 90 bp for interaction of two MREs, but the range for efficient stimulation of transcription from a TATA-box appears to be shorter. Stimulation of MT gene transcription by heavy metals is probably mediated by heavy metal-activated regulatory proteins binding cooperatively to the multiple MREs.

Animals↗
PubMed1985

Building a metal-responsive promoter with synthetic regulatory elements.

A fusion gene consisting of the promoter region from the mouse metallothionein-I gene joined to the coding region of the herpes simplex virus thymidine kinase gene is efficiently regulated by zinc in a transient assay when transfected into baby hamster kidney cells. Analysis of similar plasmids in which the metallothionein-I promoter region was mutated indicated the presence of multiple metal regulatory elements (MREs) between -176 and -44 base pairs from the cap site. To further investigate the function of MREs, we inserted a synthetic DNA fragment containing the sequence of MRE-a (the element between -55 and -44 base pairs) into the nonresponsive promoter of the thymidine kinase gene in various positions and configurations. Little or no induction by zinc was observed with single insertions of the regulatory sequence, whereas many different constructions having two copies of MRE-a were inducible. The precise position of the two MREs relative to each other or to the thymidine kinase promoter elements had a relatively small effect on the efficiency of induction, but the inducibility could be further increased by the introduction of more MRE-a sequences. MRE-a can function synergistically with the thymidine kinase distal promoter elements, but in the presence of the TATA box alone it functions as a positive, zinc-dependent promoter element.

Animals↗
PubMed1984

A 12-base-pair DNA motif that is repeated several times in metallothionein gene promoters confers metal regulation to a heterologous gene.

To define DNA sequences involved in mouse metallothionein-I (MT-I) gene promoter function and metal regulation, we fused the 5' flanking sequences of the MT-I gene to the coding sequences of a viral thymidine kinase (TK) gene. A series of 5' deletion, 3' deletion, linker-scanning, and internal deletion mutants of the MT-I promoter was constructed and assayed by microinjection into mouse eggs. The results indicate that at least two related promoter elements can confer some metal regulation independently. Those mutations that had the most severe effect on regulation impinge on a 12-base-pair conserved sequence that is repeated several times within the mouse MT-I and other MT promoters. To test the regulatory function of this sequence, it was synthesized as a pair of complementary oligonucleotides and inserted into the promoter of the TK gene. A single insertion of this sequence conferred limited metal regulation onto the TK promoter, whereas a construct with two separate inserts was regulated as efficiently as the MT-I promoter.

Animals↗
PubMed1984

Regulation, linkage, and sequence of mouse metallothionein I and II genes.

The mouse metallothionein II (MT-II) gene is located approximately 6 kilobases upstream of the MT-I gene. A comparison of the sequences of mouse MT-I and MT-II genes (as well as those of other mammals) reveals that the coding regions are highly conserved even at "silent" positions but that the noncoding regions and introns are extremely divergent between primates and rodents. There are four blocks of conserved sequences in the promoters of mouse MT-I, mouse MT-II, and human MT-IIA genes; one includes the TATAAA sequence, and another has been implicated in regulation by heavy metals. Mouse MT-I and MT-II mRNAs are induced to approximately the same extent in vivo in response to cadmium, dexamethasone, or lipopolysaccharide. Mouse MT-I and MT-II genes are regulated by metals but not by glucocorticoids after transfection into HeLa cells.

Amino Acid Sequence↗