Search PubMed⌕ Search

Biomedical subjects

G McCarthy

Publications and source records attributed to G McCarthy.

At least 55 records · Page 3Linked to original sources
PubMed1999

CAG repeat length in the hKCa3 gene and symptom dimensions in schizophrenia.

BACKGROUND: Long CAG repeats in the hKCa3 potassium channel gene have been associated with schizophrenia. We sought evidence for associations between this polymorphism and aspects of the schizophrenia phenotype. METHODS: Associations were investigated between CAG repeat length and gender, age of illness onset, and psychotic symptom dimensions in 203 unrelated individuals with DSM-IIIR schizophrenia. RESULTS: No association was found between CAG repeat length and gender or age of onset. Long CAG repeats were associated with higher negative symptom dimension scores. CONCLUSIONS: This study provides preliminary evidence that genetic liability to negative symptoms in schizophrenia may be partly mediated through the hKCa3 gene.

Adult↗
PubMed1999

ERP evidence of developmental changes in processing of faces.

OBJECTIVES: There is disagreement in the behavioural literature, as to whether face processing undergoes qualitative or quantitative change with age. METHODS: We studied event-related potentials (ERPs) associated with facial processing in 48 children (4-14 years) and 12 adults. Five categories of stimuli were presented: faces, cars, scrambled faces, scrambled cars, butterflies. The butterflies were targets (P = 12%); the other stimulus categories were equally represented and all were non-targets. RESULTS: An N170 was recorded only to the faces at posterior temporal sites and in adults it was largest at T6'. This component was seen across age groups, but at steadily increasing latencies in younger children. Age-related increases in N170 amplitude were found at T6'. In children under 12 years of age, the frontal P170 was not reliably seen. CONCLUSION: This study suggests that the underlying neural basis associated with processing faces matures in a gradual, quantitative manner throughout childhood.

Adolescent↗
PubMed1999

A two-stage genome scan for schizophrenia susceptibility genes in 196 affected sibling pairs.

We undertook a systematic search for linkage in 196 affected sibling pairs (ASPs) with DSMIV schizophrenia. In stage 1 we typed 97 ASPs with 229 microsatellite markers at an average inter-marker distance of 17.26 cM. Multipoint affected sib pair analysis identified seven regions with a maximum lod score (MLS) at or above the level associated with a nominal pointwise significance of 5%, on chromosomes 2q, 4p, 10q, 15q, 18p, 20q and Xcen. In stage 2 we genotyped a further 54 markers in 196 ASPs together with parents and unaffected siblings. This allowed the regions identified in stage 1 to be typed at an average spacing of 5.15 cM, while the region of interest on chromosome 2 was typed to 9.55 cM. Analysis was performed on the whole data set. Simulation studies suggested that we would expect one multipoint MLS of 1.5 per genome scan in the absence of linkage. An MLS of 3 would be expected only once in every 20 genome scans and thus corresponds to a genome-wide significance of 0.05. We obtained three multipoint MLSs >1.5 and, on this basis, the results on chromosomes 4p, 18q and Xcen can be considered suggestive. However, none approached a genome-wide significance of 0. 05. The power of this study was >0.95 to detect a susceptibility locus of lambda(s)= 3 with a genome-wide significance of 0.05, but only 0.70 to detect a locus of lambda(s)= 2. Our results suggest that common genes of major effect (lambda(s)> 3) are unlikely to exist for schizophrenia.

Chromosome Mapping↗
PubMed1999

Functional magnetic resonance imaging identifies abnormal visual cortical function in patients with occipital lobe epilepsy.

PURPOSE: To determine whether functional magnetic resonance imaging (fMRI) can reliably identify lateralized cortical dysfunction in patients with suspected occipital lobe epilepsy. METHODS: We compared visual cortical function of 10 patients with intractable occipital lobe epilepsy with nine control subjects' fMRI. Visual stimulation by using an alternating checkerboard pattern results in transient increases in the intensity of the proton magnetic resonance signal of water in the occipital lobes during echo-planar imaging. We used these stimulus-dependent changes in signal intensity to construct functional activation maps, which we registered onto anatomic images. RESULTS: After full-field stimulation, none of the patients with occipital lobe epilepsy had normal activation patterns, whereas eight of the nine control subjects had normal patterns (p = 0.001). Abnormalities consisted of either a markedly asymmetric activation pattern in six of 10 patients (p = 0.04), or a complete absence of activation in four of 10 patients (p = 0.05). The abnormal side of activation was concordant with the side of seizure onset in all six patients with asymmetric activation maps. Half-field stimulation produced less reliable results. Although more patients had abnormal activation maps than did controls with half-field stimulation (p = 0.04), the abnormal side was discordant with the side of seizure onset in three of the five patients who had markedly asymmetric activation patterns. CONCLUSIONS: These results suggest that fMRI with full-field stimulation is a reliable, noninvasive method for identifying areas of abnormal visual cortical function ipsilateral to the epileptogenic region in patients with occipital lobe epilepsy.

Adolescent↗
PubMed1999

Rate of psychiatric illness 1 year after traumatic brain injury.

OBJECTIVE: Neurobehavioral symptoms are not uncommon after a traumatic brain injury. However, psychiatric syndromes per se have rarely been studied in patients with such an injury. The purpose of this study was to evaluate the type and extent of psychiatric syndromes in patients with traumatic brain injury. METHOD: One hundred ninety-six hospitalized adults were studied 1 year after a traumatic brain injury with the use of a two-stage psychiatric diagnostic procedure. Psychiatric diagnoses were made according to ICD-10 criteria on the basis of data from the Schedules for Clinical Assessment in Neuropsychiatry interview. RESULTS: Of 164 patients interviewed, 30 (18.3%) had an ICD-10 diagnosis of a psychiatric illness. Among the 120 patients who were 18-64 years old, 21.7% had a psychiatric illness, compared with 16.4% in a study of the general population. A depressive illness was present in 13.9% of the traumatic brain injury patients, compared with 2.1% of the general population, and panic disorder was present in 9.0%, compared with 0.8% of the general population. CONCLUSIONS: In comparison with the general population, a higher proportion of adult patients had developed psychiatric illnesses 1 year after a traumatic brain injury; the rates of depressive episode and panic disorder were significantly higher in the study group. A history of psychiatric illness, an unfavorable global outcome according to the Glasgow Outcome Scale, a lower score on the Mini-Mental State examination, and fewer years of formal education seemed to be important risk factors in the development of a psychiatric illness. Compensation claims, however, were not associated with the rate of psychiatric illness.

Adolescent↗
PubMed1999

Attachment style and adult love relationships and friendships: a study of a group of women at risk of experiencing relationship difficulties.

This study examines the relationship between attachment style and love relationships and friendships in a group of women (N = 40) known to be at risk of experiencing relationship problems. The association between attachment style and measures of self-esteem and depression were also investigated. Women with a secure attachment style had more positive ratings in the domain of adult love relationships than women with insecure attachment style (avoidant and ambivalent) and difficulties in adult love relationships were found to be particularly related to an avoidant attachment style. Insecure attachment style was also related to having cohabited with a deviant partner. Adult attachment style was not found to be related to ratings of current mood but was significantly related to self-esteem and to ratings of functioning in the domain of adult friendships. In particular, participants with an anxious-ambivalent attachment style had more negative self-esteem than secure participants. Secure participants had more positive ratings in the domain of adult friendships than insecure participants and a moderately significant association was also found between difficulties in the domain of adult friendships and an anxious-ambivalent attachment style. In addition, 20% (N = 8) of the women also reported attachment styles characterized by high levels of avoidance and ambivalence: this group was found to have more pervasive difficulties in their close relationships than women who endorsed a single dominant attachment style.

Adult↗
PubMed1999

Comparative localization of auditory comprehension by using functional magnetic resonance imaging and cortical stimulation.

OBJECT: The authors previously described a functional magnetic resonance (fMR) imaging task for the localization of auditory comprehension in which focal activation of posterior temporal and inferior frontal regions of the left hemisphere was reliably demonstrated. Because this study was conducted in neurologically normal volunteers, it was not possible to determine whether the activated regions were critical to the performance of language tasks; that is, whether the fMR imaging activations provided a valid measure of language processing. A direct comparison of fMR imaging language activation with cortical stimulation must be completed before it can be used with confidence in presurgical planning, and this comparison is performed in the present study. METHODS: The authors report on a series of 33 consecutive patients who underwent dominant hemisphere resection and in whom fMR imaging mapping of auditory comprehension was performed at the Yale neurosurgical program. In 23 of the 33 patients fMR imaging activation was consistent with the typical results obtained in normal participants in the earlier study. In 16 of these 23 patients language mapping was performed using either intra- or extraoperative cortical stimulation. Cortical stimulation failed to localize language areas in two of the 16 patients. Electrical stimulation that was performed in proximity to the fMR image activations interfered with auditory comprehension, object naming, or speech production in 12 of the remaining 14 patients. Five of the 10 cases in which evocation of reliable fMR imaging activation failed were attributable to technical problems and/or patient head movement. CONCLUSIONS: Cortical stimulation results and fMR imaging findings were consistent in all but two patients. However, the spatial extent of the activation produced by fMR imaging and the spatial extent of stimulation-induced language disruption that was caused by direct cortical stimulation did not always correspond. Problems in defining the extent of activation by both methods are discussed.

Adolescent↗
PubMed1999

Avoidant/ambivalent attachment style as a mediator between abusive childhood experiences and adult relationship difficulties.

The role of attachment style, self-esteem, and relationship attributions as possible mediators between abusive childhood experiences and difficulties in establishing supportive love relationships in adulthood were investigated in a sample of women known to be at risk of experiencing relationship problems. Measures of child abuse, the quality of love relationships, and the three potential mediators were made concurrently in adulthood. Participants who had experienced child abuse were found to be six times more likely to be experiencing difficulties in the domain of adult love relationships than those who had not. Self-esteem and relationship attributions were not found to be related to child abuse. When both child abuse and avoidant/ambivalent attachment style were considered together avoidant/ambivalent attachment style, but not child abuse, was found to be related to relationship difficulties. These findings indicate that avoidant/ambivalent attachment style, but not self-esteem and relationship attributions, is a mediating factor in the route from child abuse to adult relationship abilities.

Adult↗
PubMed1999

Event-related potentials and functional MRI: a comparison of localization in sensory, perceptual and cognitive tasks.

Combining ERP and fMRI methods to elucidate the time course and anatomical basis of information processing may provide a powerful new tool for understanding human brain function. Attempts to model the time course of fMRI activations by recording surface electromagnetic fields require a better understanding of the relationship between ERPs and fMRI activations. The results presented here show that good correspondence can be obtained between the location of ERP generators and fMRI activations in sensorimotor cortex, and in face perception and target detection tasks. However, difficulties in obtaining somatosensory fMRI activations with stimuli known to evoke robust SEPs, and the lack of fMRI activations within the hippocampus in tasks that elicit large hippocampal field potentials suggest that not all stimuli or tasks that evoke focal ERPs will evoke fMRI activations. This may be related to differences in the sensitivity of the fMRI that will be overcome with better technique and with more sensitive instruments. However, caution must be exercised in developing models that assume a one-to-one correspondence between ERP generators and fMRI activations.

Cognition↗
PubMed1998

Temporal cortex activation in humans viewing eye and mouth movements.

We sought to determine whether regions of extrastriate visual cortex could be activated in subjects viewing eye and mouth movements that occurred within a stationary face. Eleven subjects participated in three to five functional magnetic resonance imaging sessions in which they viewed moving eyes, moving mouths, or movements of check patterns that occurred in the same spatial location as the eyes or mouth. In each task, the stimuli were superimposed on a radial background pattern that continually moved inward to control for the effect of movement per se. Activation evoked by the radial background was assessed in a separate control task. Moving eyes and mouths activated a bilateral region centered in the posterior superior temporal sulcus (STS). The moving check patterns did not appreciably activate the STS or surrounding regions. The activation by moving eyes and mouths was distinct from that elicited by the moving radial background, which primarily activated the posterior-temporal-occipital fossa and the lateral occipital sulcus-a region corresponding to area MT/V5. Area MT/V5 was also strongly activated by moving eyes and to a lesser extent by other moving stimuli. These results suggest that a superior temporal region centered in the STS is preferentially involved in the perception of gaze direction and mouth movements. This region of the STS may be functionally related to nearby superior temporal regions thought to be involved in lip-reading and in the perception of hand and body movement.

Adult↗
PubMed1998

Functional MRI studies of auditory comprehension.

The location of brain regions essential for auditory language comprehension is an important consideration in the planning of neurosurgical procedures that involve resections within the dominant temporal lobe. Language testing during intraoperative and extraoperative cortical stimulation has been the primary method for localizing these regions; however, noninvasive alternatives using functional neuroimaging have been sought. Here we report on a study of 14 subjects who listened passively to alternating sentences spoken in their native English language and in unfamiliar Turkish while functional magnetic resonance images were acquired. The English sentences produced strong activation within the left superior temporal sulcus in all subjects. Lesser activation was seen in homotopic right hemisphere locations in several subjects. In addition to these posterior temporal activations, 8 subjects also showed activation to English sentences in the left inferior frontal gyrus. Turkish sentences evoked no coherent region of activation in any subject. As both the Turkish and English sentences were read by the same speaker, and were matched for length, volume, and intonation, we conclude that the activation pattern evoked by the English sentences reflects auditory comprehension. This conclusion is further supported by additional control studies that have shown a markedly different pattern of activation by pure tone frequency glides.

Acoustic Stimulation↗
PubMed1998

A comparison of bone scintigraphy and MRI in the early diagnosis of the occult scaphoid waist fracture.

OBJECTIVE: To determine the accuracy of MRI in the assessment of the radiographically occult scaphoid fracture. DESIGN: This prospective study compared the sensitivity and specificity of MRI for detection of radiographically occult scaphoid fractures with bone scintigraphy (BS), the currently accepted imaging modality of choice. Consecutive patients with clinical signs of a scaphoid injury but no evidence of fracture on plain radiographs at presentation and after 7-10 days were evaluated by MRI and BS. All images were reported in masked fashion and the sensitivities and specificities of the imaging modalities determined. All patients with a scaphoid fracture demonstrated by MRI or BS were followed for at least a year after injury. PATIENTS: Forty-three subjects (aged 12-74 years) had both MRI and BS carried out on average 19 days from the injury date. RESULTS AND CONCLUSIONS: Six patients (14%) had scaphoid waist fractures. There were other bony injuries in a further six. In 40 patients there was agreement between the BS and MRI findings. In three cases there was discrepancy between the imaging modalities; in all three MRI was found to be the more sensitive and specific. MRI could become the investigation of choice for this injury.

Adolescent↗
PubMed1998

Further support for an association between a polymorphic CAG repeat in the hKCa3 gene and schizophrenia.

A recent study has suggested that a polymorphism in the hKCa3 potassium channel may be associated with raised susceptibility to schizophrenia. Despite its modest statistical significance, the study is intriguing for two reasons. First, hKCa3 contains a polymorphic CAG repeat in its coding sequence, with large repeats more common in schizophrenics compared with controls. This is interesting in view of several repeat expansion detection (RED) studies that have reported an excess of large CAG repeats in psychotic probands. Second, the hKCa3 gene is a functional candidate gene because studies of antipsychotic and psychotogenic compounds suggest that glutamatergic systems modulated by SKCa channels may be important in schizophrenia pathogenesis. In the light of the above, we have tested the hypothesis of an association between schizophrenia and the hKCa3 CAG repeat polymorphism using a case control study design. Under the same model of analysis as the earlier study, schizophrenic probands had a higher frequency of alleles with greater than 19 repeats than controls (chi 2 = 2.820, P = 0.047, 1-tail). Our data therefore provide modest support for the hypothesis that polymorphism in the hKCa3 gene may contribute to susceptibility to schizophrenia.

Alleles↗
PubMed1998

Modulation of human extrastriate visual processing by selective attention to colours and words.

The present study investigated the effect of visual selective attention upon neural processing within functionally specialized regions of the human extrastriate visual cortex. Field potentials were recorded directly from the inferior surface of the temporal lobes in subjects with epilepsy. The experimental task required subjects to focus attention on words from one of two competing texts. Words were presented individually and foveally. Texts were interleaved randomly and were distinguishable on the basis of word colour. Focal field potentials were evoked by words in the posterior part of the fusiform gyrus. Selective attention strongly modulated long-latency potentials evoked by words. The attention effect co-localized with word-related potentials in the posterior fusiform gyrus, and was independent of stimulus colour. The results demonstrated that stimuli receive differential processing within specialized regions of the extrastriate cortex as a function of attention. The late onset of the attention effect and its co-localization with letter string-related potentials but not with colour-related potentials recorded from nearby regions of the fusiform gyrus suggest that the attention effect is due to top-down influences from downstream regions involved in word processing.

Action Potentials↗
PubMed1998

Attachment representations and representations of the self in relation to others: a study of preschool children in inner-city London.

The study examined the relationship between attachment representations and representations of the self in relation to others in a sample of 42 children aged between 4 and 5.9 years. The relationship between children's attachment representations and parents' style of regulating negative affect was also explored. The families were using local authority day-care facilities in a deprived inner-city area of London. The quality of attachment representations was assessed using a modified version of the Separation Anxiety Test. Assessments of the representation of the self in relation to others consisted of (a) assessment of the child's view of self within the relationship with the attachment figure, using an incomplete doll story procedure; and (b) assessment of the child's perceptions of the way others view them using a puppet interview. Significant connections between attachment representations, representations of self in relation to others, and parents' negative affect regulation were found. Children with secure attachment representations had a significantly more positive view of the self in the relationship with the attachment figure than children with disorganized attachment representations, and a significantly more positive perception of the way others view them than children with avoidant attachment representations. Children with secure attachment representations had parents with more adaptive ways of regulating their own negative affect than children with ambivalent or disorganized attachment representations.

Child Day Care Centers↗
PubMed1998

The calcaneum as a site for intraosseous infusion.

Intraosseous infusion has been recommended as a rapid and effective form of circulatory access in the collapsed child. Recognised sites for insertion include the tibia, femur, iliac crest, sternum, and clavicle. The case of a 3 year old collapsed child is described who was successfully resuscitated with the use of an intraosseous needle placed in the calcaneum; the method of needle insertion is also detailed.

Calcaneus↗
PubMed1998

Teaching medical students on the ethical dimensions of human rights: meeting the challenge in South Africa.

SETTING: Previous health policies in South Africa neglected the teaching of ethics and human rights to health professionals. In April 1995, a pilot course was run at the University of Cape Town in which the ethical dimensions of human rights issues in South Africa were explored. OBJECTIVES: To compare knowledge and attitudes of participating students with a group of control students. DESIGN: Retrospective cohort study. SUBJECTS: Seventeen fourth-year medical students who participated in the course and 13 control students from the same class, matched for gender. INTERVENTIONS: Students participated in a one-week module on ethics and human rights. Five months after the course had been run, students completed a semi-structured questionnaire exploring their knowledge and attitudes with regards to ethics and human rights issues. MAIN OUTCOME MEASURES: Knowledge scores, attitude scores and various individual indicators of attitude. RESULTS: Clear benefits for overall knowledge score, for four out of five individual knowledge questions and for one of the attitude questions, were demonstrated. Participating students also appeared to be more convinced of the need for teaching on the ethical dimensions of human rights at postgraduate level and that such teaching should also be integrated in the curriculum. The low response rate amongst controls may have selected students who were more socially conscious, thereby leading to an underestimate of the true impact of the course. CONCLUSION: The evaluation indicates clear benefits of the course for undergraduate students, and supports arguments for the inclusion of such courses in the training of health professionals. This is particularly important given the challenges posed by the Truth and Reconciliation Commission to the health professions to address past complicity in human rights abuses through reorientation of medical training in South Africa.

Adult↗