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Biomedical subjects

G L Morris

Publications and source records attributed to G L Morris.

At least 19 recordsLinked to original sources
PubMed1996

Event-related potentials during the Continuous Visual Memory Test.

The Continuous Visual Memory Test (CVMT; Trahan & Larrabee, 1988) is a recognition format assessment of figural memory. It includes 112 ambiguous designs presented sequentially, with a number of designs that recur through the 112 presentations. The patient's task is to identify the recurring figures by responding with the word "old" for recurring stimuli and "new" for non-recurring stimuli. This study examined cortical event-related potentials during discrimination of old vs. new stimuli. While no latency differences between stimuli were found, P300 amplitude was greater during recognition of old stimuli and increasingly prominent at anterior sites. A stimulus by electrode site interaction suggests greater functional involvement in the discrimination by the frontal areas. This points to a degree of psychophysiological validation of the CVMT and cortical specificity of the task.

Adolescent↗
PubMed1996

Functional magnetic resonance imaging mapping of the motor cortex in patients with cerebral tumors.

OBJECTIVE: The purpose of this study was to determine the usefulness of functional magnetic resonance imaging (FMRI) to map cerebral functions in patients with frontal or parietal tumors. METHODS: Charts and images of patients with cerebral tumors or vascular malformations who underwent FMRI with an echoplanar technique were reviewed. The FMRI maps of motor (11 patients), tactile sensory (12 patients), and language tasks (4 patients) were obtained. The location of the FMRI activation and the positive responses to intraoperative cortical stimulation were compared. The reliability of the paradigms for mapping the rolandic cortex was evaluated. RESULTS: Rolandic cortex was activated by tactile tasks in all 12 patients and by motor tasks in 10 of 11 patients. Language tasks elicited activation in each of the four patients. Activation was obtained within edematous brain and adjacent to tumors. FMRI in three cases with intraoperative electrocortical mapping results showed activation for a language, tactile, or motor task within the same gyrus in which stimulation elicited a related motor, sensory, or language function. In patients with > 2 cm between the margin of the tumor, as revealed by magnetic resonance imaging, and the activation, no decline in motor function occurred from surgical resection. CONCLUSIONS: FMRI of tactile, motor, and language tasks is feasible in patients with cerebral tumors. FMRI shows promise as a means of determining the risk of a postoperative motor deficit from surgical resection of frontal or parietal tumors.

Adolescent↗
PubMed1996

Totally automated analysis by robotized PrepStation and liquid chromatography: direct-sample analysis of felbamate.

A totally automated analysis of felbamate was developed by using a robotized PrepStation for extraction, followed by automated liquid chromatographic (LC) analysis and data reduction. This is one of the newer direct-sample analysis approaches by LC. Felbamate was a previously approved antiepileptic agent used to treat partial seizures with and without generalization and to treat Lennox-Gastaut syndrome in pediatric patients. However, due to the reported incidences of aplastic anemia, its clinical application was recently restricted to the treatment of the latter syndrome. The automated assay using Bench Supervisor, PrepStation, and LC, based on a previously developed manual method, used 200 microliters of serum standards, quality control, or patients' plasma. These were mixed with 600 microliters of internal standard (IS) W509 dissolved in acetonitrile for protein precipitation. After axial centrifugation and standing, aliquots of the clear supernatant were transferred and washed with hexane. Aliquots of the supernatant were transferred and injected into a high-performance liquid chromatograph (HPLC). HPLC parameters included an mu Bondapak C-18 column, phosphate/acetonitrile (8:2) as mobile phase, and detection at 214 nm. Retention times were 2.9 and 4.2 min for felbamate and IS, respectively. Calibration was linear for concentrations from 10 to 200 mg/L with r > 0.994. Precision studies showed coefficients of variation ranging from 2.7% to 8.8%. Correlation with the manual method showed that r = 0.934, slope = 1.048, intercept = -2.642, and n = 21. Phenobarbital coeluted with the IS. This study demonstrated the feasibility of using a robotized, automated method for monitoring felbamate, readily extended to monitoring other antiepileptic drugs with minimal modification.

Anticonvulsants↗
PubMed1996

Determination of language dominance using functional MRI: a comparison with the Wada test.

We performed functional MRI (FMRI) in 22 consecutive epilepsy patients undergoing intracarotid amobarbital (Wada) testing and compared language lateralization measures obtained with the two procedures. FMRI used a single-word semantic decision task previously shown to activate lateralized language areas in normal adults. Correlation between the two tests was highly significant (r = 0.96; 95% CIs 0.90 to 0.98; p < 0.0001). These results validate the FMRI technique and suggest that "active" areas observed with this semantic processing task correspond to those underlying hemispheric dominance for language. This strong correlation observed supports the view that language lateralization is a continuous rather than a dichotomous variable. In addition to lateralization information, FMRI consistently demonstrated focal regions of activity in lateral frontal and temporo-parieto-occipital cortex. These functional maps may be helpful in defining the boundaries of surgical excisions.

Adolescent↗
PubMed1995

Functional magnetic resonance imaging mapping of the sensorimotor cortex with tactile stimulation.

The purpose of this study is to compare tactile stimulation of the palm with voluntary movement of the fingers as paradigms for mapping the sensorimotor cortex in functional magnetic resonance imaging. In 22 subjects, 24 sets of functional magnetic resonance images were obtained with echoplanar acquisitions and cross-correlation image processing techniques. Two tasks were employed: a motor task in which subjects moved the thumb and index finger of one hand and a sensory task in which the palm was scratched by another person. The activation from the two tasks coincided entirely in 20 sets and partially in 3 sets. In one case, no activation was seen with the motor task. The study suggests that tactile stimulation of the palm is useful and reliable for mapping the sensorimotor cortex.

Adult↗
PubMed1995

A comparison of functional MR activation patterns during silent and audible language tasks.

PURPOSE: To compare word generation tasks performed silently and aloud as paradigms for functional MR. METHODS: Images were obtained at 1.5 T, with echoplanar acquisition in nine subjects performing word generation aloud or silently. Functional images created from the echoplanar images by means of cross-correlation techniques were superimposed on anatomic reference images. The location of activation from the two tasks was tabulated; the number of activated pixels in each region from the two tasks was compared. RESULTS: Both silent and aloud word generation produced activation in the inferior frontal lobes, sensorimotor cortex regions, supplementary motor areas, and anterior cingulate gyri, predominantly in the dominant hemisphere. Significantly more activated pixels and fewer artifacts were detected with silent word generation than with word generation aloud. CONCLUSION: Word generation silently or aloud produce activation in the brain. Greater activation can be detected in the left frontal lobe with silent word generation, although the subject's performance of the task cannot be monitored independently during silent word generation.

Adult↗
PubMed1994

The results of computer-assisted ambulatory 16-channel EEG.

The objective of this study was to examine the results of 16-channel computer-assisted outpatient long-term EEG monitoring (CO-LTM) and to compare those results to previously published reports using 4- and 8-channel ambulatory cassette-based continuous recordings. Patients were referred to a community-based outpatient EEG service for further diagnostic evaluation using this 16-channel bipolar recording system. 344 patients were recorded for an average of 1.4 days. EEG was reviewed for the presence of patient identified events, computer identified interictal and ictal abnormalities, and periodic time samples. A push-button recording that signified a clinical event was obtained in 166 patients (48.3%); 41 (11.9%) of these recordings included a seizure and 125 (36.3%) showed no EEG changes during the habitual event. An EEG abnormality was identified by the computer in an additional 90 recordings (26.2%), for an overall clinical usefulness of 74.4%. Among the 191 patients referred with previously normal routine EEGs, a total of 129 (67.5%) of these recordings were useful. 48 (25.1%) of these tracings were abnormal and an additional 81 push-button events (42.4%) showing no changes from background EEG were recorded. In conclusion, computer-assisted outpatient EEG monitoring provides good success rates for clinically useful information.

Adolescent↗
PubMed1994

Functional magnetic resonance imaging of somatosensory stimulation.

Functional magnetic resonance imaging (FMRI) has detected changes in regional cerebral blood flow and volume in response to motor movements, visual stimuli, and auditory stimuli in each of their respective primary cortices. This experiment was conducted to determine whether signal changes in the somatosensory cortex secondary to tactile stimulation could be demonstrated. The palm of the right hand was periodically stimulated while the subject was undergoing echo-planar imaging with a 1.5-T magnetic resonance scanner equipped with local gradient and radio frequency coils. Sagittal and coronal images of 10- to 15-mm slice thickness were selected to include the postcentral gyrus and surrounding regions. Temporally correlated signal changes of 1% to 5% occurred in the peri-rolandic region in each of six subjects. The time course of signal changes was comparable to that found in other primary sensory and motor cortices. The results provide preliminary evidence of the sensitivity of FMRI to activation of the somatosensory cortex with tactile stimulation and support FMRI as a promising noninvasive technique for study of the functional organization and integrity of the cerebrum.

Adult↗
PubMed1993

Functional magnetic resonance imaging of complex human movements.

Functional magnetic resonance imaging (FMRI) is a new, noninvasive imaging tool thought to measure changes related to regional cerebral blood flow (rCBF). Previous FMRI studies have demonstrated functional changes within the primary cerebral cortex in response to simple activation tasks, but it is unknown whether FMRI can also detect changes within the nonprimary cortex in response to complex mental activities. We therefore scanned six right-handed healthy subjects while they performed self-paced simple and complex finger movements with the right and left hands. Some subjects also performed the tasks at a fixed rate (2 Hz) or imagined performing the complex task. Functional changes occurred (1) in the contralateral primary motor cortex during simple, self-paced movements; (2) in the contralateral (and occasionally ipsilateral) primary motor cortex, the supplementary motor area (SMA), the premotor cortex of both hemispheres, and the contralateral somatosensory cortex during complex, self-paced movements; (3) with less intensity during paced movements, presumably due to the slower movement rates associated with the paced (relative to self-paced) condition; and (4) in the SMA and, to a lesser degree, the premotor cortex during imagined complex movements. These preliminary results are consistent with hierarchical models of voluntary motor control.

Adult↗
PubMed1991

Phospholamban regulation of cardiac sarcoplasmic reticulum (Ca(2+)-Mg2+)-ATPase. Mechanism of regulation and site of monoclonal antibody interaction.

Monoclonal antibodies raised against canine cardiac sarcoplasmic reticulum phospholamban were used to study the structure-function relationship between phospholamban and the sarcoplasmic reticulum (SR) (Ca(2+)-Mg2+)-ATPase (Suzuki, T., and Wang, J. H. (1986) J. Biol. Chem. 261, 7018-7023). Additional monoclonal antibodies are characterized further. When five of these monoclonal antibodies were assessed for their ability to affect SR Ca2+ uptake three of these antibodies had no effect on SR Ca2+ uptake, whereas the other two monoclonals were able to stimulate SR Ca2+ uptake to levels similar to those caused by phosphorylation of phospholamban at different calcium concentrations. Using synthetic peptides corresponding to various portions of phospholamban in a competitive binding assay, it was possible to map the epitope site of monoclonals which stimulate the (Ca(2+)-Mg2+)-ATPase activity to phospholamban residues 7-16. These results implicate phospholamban residues 7-16 in the regulation of the (Ca(2+)-Mg2+)-ATPase.

Amino Acid Sequence↗
PubMed1991

Postictal language assessment and lateralization of complex partial seizures.

We performed a prospective study of ictal and postictal language function after 105 temporal lobe complex partial seizures in 26 patients. Seizure localization was verified by a greater than 90% reduction in seizure frequency after temporal lobectomy. At the time of the seizure, the patient was asked to read a test phrase aloud until it was read correctly and clearly. In all 62 seizures originating from the left temporal lobe, the patient took more than 68 seconds to read the test phrase correctly (mean, 321.9 seconds); in 42 of 43 seizures from the right temporal lobe, the patient read the test phrase in less than 54 seconds (mean, 19.7 seconds). Postictal paraphasias occurred in 46 of 62 seizures from the left temporal lobe (11 of 14 patients). In this study, quantifying the time delay in reading a test phrase lateralized seizure onset in all 26 patients tested, proving significantly more accurate than any other single noninvasive presurgical test.

Adolescent↗
PubMed1990

Epidermal growth factor receptor mRNA levels in human prostatic tumors and cell lines.

The mitogenic activity of epidermal growth factor (EGF) is mediated by a cell surface receptor (EGF-R) which has been identified in human prostate tissues. Because of conflicting reports on the relative levels of EGF-R in prostate tumors as measured by binding of radiolabelled EGF, we have examined EGF-R expression at the level of the specific messenger RNA using a sensitive RNase protection assay. Expression of the mRNA for EGF-R was higher in carcinoma (CaP, N = 38) than in benign prostatic hyperplasia (BPH, N = 35) samples (p less than 0.01). The highest levels of EGF-R mRNA were found in the human prostatic carcinoma cell lines, PC-3 and DU145. Among the CaP samples, there was an association of higher EGF-R mRNA levels with higher tumor extent and dedifferentiation. Since EGF has also been found in prostatic tissues, the enhanced expression of the EGF-R gene may play a role in the growth of prostate tumors, possibly by an autocrine pathway.

Carcinoma↗
PubMed1989

Posterior ischemic optic neuropathy due to Aspergillus fumigatus.

A 35-year-old woman with metastatic breast cancer experienced acute monocular visual loss. Her fundus examination was normal. The patient died 48 h later, and autopsy demonstrated hematogenously disseminated aspergillosis. The retrobulbar optic nerve of the affected eye showed infarction due to massive embolization with Aspergillus fumigatus. Although the retrobulbar optic nerve is relatively resistant to ischemia, its meningeal derived blood supply may be occluded by massive showers of emboli.

Adult↗
PubMed1988

Some indicators of welfare of crated veal calves on three dietary iron regimens.

Holstein calves were managed from less than 1 wk of age as in the special-fed veal industry but subjected to three dietary regimens (n = 10/group): low dietary iron (LI = approximately 5 mg iron/kg dry milk replacer) throughout 16 wk; 2) high then low dietary iron (H-LI = 140 mg/kg through d 18, then approximately 5 mg/kg through wk 16; a typical industrial scheme) or 3) high dietary iron (HI = approximately 105 mg/kg throughout the study). Several physiologic, behavioral and health indicators of welfare were monitored at various times. From wk 7 on, blood hemoglobin concentration was higher in HI calves than in LI, whereas that in H-LI calves was intermediate. Blood red cell count was higher in HI calves than in LI from wk 11 to 16, and was higher in HI than in H-LI from wk 14 to 16. Ratio of blood segmented neutrophils to lymphocytes (an indicator of stress) did not differ due to dietary regimen. Between wk 2 and 16, lying time increased from 69.5 to 76.6% of total time. Oral behaviors (e.g., licking and gnawing) occupied less than 15% of total time. Dietary regimen did not affect time spent either lying or engaging in oral behaviors. Calves in all dietary-regimen and slaughter-age groups experienced high frequencies of pneumonia, digestive-tract maladies and trichobezoars, but neither disease nor medical-treatment frequency was related to dietary regimen. Live, hot-dressed carcass and liver weights of the five calves/group slaughtered at 16 wk were not affected by dietary regimens, but carcass grade was highest for LI calves and lowest for HI.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1987

Brain stem evoked response in the assessment of learning disabilities.

Evidence has accumulated rapidly to support the hypothesis that neurological anomalies underlie specific forms of learning disability (LD). This article reviews recent studies directed at the electrophysiological assessment of LD children, with emphasis on the brain stem evoked response(BSER) methodology. Child studies appear to indicate that there are significant differences in BSERs between LD and age-matched normal controls. The methodological and statistical differences among these studies, which have clouded the findings and made replication difficult, are reviewed. Improvements in sampling and empirical procedures are suggested, including the use of discriminant analysis to explore BSER asymmetries in LD children. Future inquiry into the measurement and analysis of BSER activity in LD populations is warranted on the basis of these preliminary findings. New information may bring professionals closer to an understanding of the neurological causes of specific subtypes of LD and permit earlier identification of these "at risk" populations.

Adolescent↗