Biomedical subjects

Claire McGrath

Publications and source records attributed to Claire McGrath.

4 recordsLinked to original sources

PubMed2005

Acute hemolytic transfusion reaction in a pediatric patient following transfusion of apheresis platelets.

The practice of transfusing ABO-incompatible platelets, driven primarily by concerns about inventory management, has been considered generally safe because the accompanying plasma is usually diluted in the recipient's total blood volume. However, if the platelet product contains a large volume of plasma or a high concentration of incompatible isoagglutinin, there may be hemolysis of the recipient's red cells. Patients with a small blood volume, such as babies and children, are considered to be at particular risk for such a complication. We describe the case of a baby who suffered massive hemolysis of her group A red cells after transfusion of group O Apheresis Platelets containing a high-titered anti-A isoagglutinin. We also offer a review of the literature on this subject and recommendations to avoid acute hemolytic reactions as a result of platelet transfusion.

ABO Blood-Group System↗

PubMed2003

Levels-of-processing effect on word recognition in schizophrenia.

BACKGROUND: Individuals with schizophrenia have difficulty organizing words semantically to facilitate encoding. This is commonly attributed to organizational rather than semantic processing limitations. By requiring participants to classify and encode words on either a shallow (e.g., uppercase/lowercase) or deep level (e.g., concrete/abstract), the levels-of-processing paradigm eliminates the need to generate organizational strategies. METHODS: This paradigm was administered to 30 patients with schizophrenia and 30 healthy comparison subjects to test whether providing a strategy would improve patient performance. RESULTS: Word classification during shallow and deep encoding was slower and less accurate in patients. Patients also responded slowly during recognition testing and maintained a more conservative response bias following deep encoding; however, both groups showed a robust levels-of-processing effect on recognition accuracy, with unimpaired patient performance following both shallow and deep encoding. CONCLUSIONS: This normal levels-of-processing effect in the patient sample suggests that semantic processing is sufficiently intact for patients to benefit from organizational cues. Memory remediation efforts may therefore be most successful if they focus on teaching patients to form organizational strategies during initial encoding.

Adult↗

PubMed2002

Brain activation during facial emotion processing.

Functional neuroimaging studies have helped identify neural systems involved in cognitive processing and more recently have indicated limbic activation to emotional stimuli. Some functional magnetic resonance imaging (fMRI) studies have reported increased amygdala response during exposure to emotional stimuli while others have not shown such activation. The present study was designed to test the hypothesis that activation of the amygdala is related to the relevance of the emotional valence of stimuli. Healthy young participants (7 men, 7 women) were studied in a high-field (4 tesla) scanner using blood oxygenation-level dependent (BOLD) signal changes in a blocked "box car" design. They viewed facial displays of happiness, sadness, anger, fear, and disgust as well as neutral faces obtained from professional actors and actresses of diverse ethnicity and age. Their task alternated between emotion discrimination (indicating whether the emotion was positive or negative) and age discrimination (indicating whether the poser was older or younger than 30). Blocks contained the same proportion of emotional and neutral faces. Limbic response was greater during the emotion than during the age discrimination conditions. The response was most pronounced in the amygdala, but was also present in the hippocampus and circumscribed voxels in other limbic regions. These results support the central role of the amygdala in emotion processing, and indicate its sensitivity to the task relevance of the emotional display.

Adult↗

PubMed2002

An fMRI study of facial emotion processing in patients with schizophrenia.

OBJECTIVE: Emotion processing deficits are notable in schizophrenia. The authors evaluated cerebral blood flow response in schizophrenia patients during facial emotion processing to test the hypothesis of diminished limbic activation related to emotional relevance of facial stimuli. METHOD: Fourteen patients with schizophrenia and 14 matched comparison subjects viewed facial displays of happiness, sadness, anger, fear, and disgust as well as neutral faces. Functional magnetic resonance imaging was used to measure blood-oxygen-level-dependent signal changes as the subjects alternated between tasks of discriminating emotional valence (positive versus negative) and age (over 30 versus under 30) of the faces with an interleaved crosshair reference condition. RESULTS: The groups did not differ in performance on either task. For both tasks, healthy participants showed activation in the fusiform gyrus, occipital lobe, and inferior frontal cortex relative to the resting baseline condition. The increase was greater in the amygdala and hippocampus during the emotional valence discrimination task than during the age discrimination task. In the patients with schizophrenia, minimal focal response was observed for all tasks relative to the resting baseline condition. Contrasting patients and comparison subjects on the emotional valence discrimination task revealed voxels in the left amygdala and bilateral hippocampus in which the comparison subjects had significantly greater activation. CONCLUSIONS: Failure to activate limbic regions during emotional valence discrimination may explain emotion processing deficits in patients with schizophrenia. While the lack of limbic recruitment did not significantly impair simple valence discrimination performance in this clinically stable group, it may impact performance of more demanding tasks.

Affect↗