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Biomedical subjects

J E Shuren

Publications and source records attributed to J E Shuren.

16 recordsLinked to original sources
PubMed1999

The safety of newly approved medicines: do recent market removals mean there is a problem?

The removal of 5 pharmaceuticals from the market in a 12-month period because of unexpected adverse events raised concerns about the adequacy of the drug review process at the US Food and Drug Administration (FDA). Specifically, concerns were raised about improvements in drug review efficiency that significantly reduced FDA review times. We have reviewed the circumstances of the 5 removals to determine whether there was any relationship to the increased efficiencies in the drug review process. When the removed drugs were analyzed by date of approval, no increase in the number of drugs taken off the market was seen, demonstrating that reduced review processing time was not the reason for the cluster of removals. We conclude that the agency's drug review procedures and postmarketing surveillance system after a drug has been marketed are currently adequate but must continually adjust to future challenges.

Adverse Drug Reaction Reporting Systems↗
PubMed1999

Apraxia and motor-skill acquisition in Alzheimer's disease are dissociable.

Many patients with Alzheimer's disease (AD) are apraxic and the apraxia has been posited to be related to a loss of movement representations. Whereas patients with Alzheimer's disease have been reported to demonstrate normal motor learning on a rotor pursuit skill acquisition task, it is unknown whether AD subjects who are apraxic demonstrate normal skill-learning. We tested subjects with probable AD and normal controls on a rotor pursuit task. We also tested the AD subjects for ideomotor apraxia. Subjects with AD who were apraxic had normal motor learning. In addition, praxis score did not correlate with performance on the skill-acquisition task. The results suggest that ideomotor praxis and motor learning are at least partly dissociable.

Aged↗
PubMed1997

The influence of center of mass effect on the distribution of spatial attention in the vertical and horizontal dimensions.

Normal subjects attend toward the middle of grouped items (center of mass effect). In order to learn if mass effect could influence performance on line bisection tasks and if the spatial orientation of the line (vertical vs. horizontal) could influence center of mass effect, we administered bisection tasks to 16 normal subjects using either lines composed of two unequal segments (one thick and one thin) or unsegmented lines. When the longer segment was to the right, left, up, or down, subjects erred by deviating their bisection toward the longer segment (center of mass effect). Our results demonstrate that the center of mass effect can be seen with bisection tasks and is greater in the vertical than in the horizontal dimension.

Adult↗
PubMed1997

Diencephalic temporal order amnesia.

OBJECTIVE: Amnesia for temporal relations may occur without amnesia for content memories. The aim was to determine whether a patient with mild memory loss due to a thalamic lesion had amnesia for temporal relations, and whether the amnesia was specific for particular material. METHODS: A male patient had an isolated right dorsomedial thalamic infarct and resolving amnesia. He was tested on tasks relating to content (what) and temporal (when) memories for both verbal and non-verbal material, three and seven months after his infarct. RESULTS: Three months after his infarct, the man had amnesia for temporal, but not content memories using non-verbal stimuli, and normal performance using verbal stimuli. Seven months after his infarct, he had a normal performance using verbal and non-verbal stimuli. CONCLUSIONS: Patients with thalamic lesions may have a material specific amnesia for temporal relations in the absence of amnesia for content.

Adult↗
PubMed1996

The role of visual imagery in spelling.

Current models of spelling posit that information from the orthographic output buffer can be translated into physical letter codes for written output or into name letter codes for spoken output. It is not known, at present, whether or not visualization of these codes is necessary to spell or recognize orally spelled words. We report a 73-year-old woman who could spell words better than she could image them and who demonstrated near flawless recognition of orally spelled words. We conclude that visual imagery is not necessary to either spell or recognize orally spelled words.

Aged↗
PubMed1996

The use of hemi-imagery for studying brain asymmetries in image generation.

To learn if there are brain asymmetries for image generation we asked 50 right-handed normal subjects to image one-half of an object and to report which half (right or left) they saw. We found that these subjects were more likely to image the right half of objects than the left. We also found that right hemi-imagers demonstrated a greater degree of right-handedness than did left hemi-imagers. Our results suggest that in strongly right-handed subjects the left hemisphere is more adept at object image generation than is the right hemisphere.

Adult↗
PubMed1996

Preserved color imagery in an achromatopsic.

The loss of color vision secondary to central nervous system disease (achromatopsia) is thought to preclude visual imagery of colors. We report a patient with achromatopsia, secondary to bilateral temporo-occipital infarcts inclusive of the lingual and fusiform gyri, with preserved color imagery. Our findings, in conjunction with previous cases in the literature, are consistent with a single neural network for color processing in which a disconnection of internal activation from stored color representations produces impaired color imagery with preserved color perception, whereas a disconnection of visual input to these representations produces achromatopsia with preserved color imagery.

Cerebral Infarction↗
PubMed1995

Repetition and the arcuate fasciculus.

According to the traditional model of language organization, repetition deficits arise following damage to the arcuate fasciculus of the dominant hemisphere (conduction aphasia). Conduction aphasia may result from lesions that spare the arcuate fasciculus. However, these patients have atypical language organization. We describe a man with normal language architecture who underwent a resection of the anterior portion of his arcuate fasciculus and retained his ability to repeat words and sentences. We propose that the arcuate fasciculus is not necessary for speech repetition by the lexical route.

Adult↗
PubMed1995

Attention and anosognosia: the case of a jargonaphasic patient with unawareness of language deficit.

Some patients with aphasia lack awareness of the language errors they make. We describe a man with undifferentiated jargonaphasia and preserved auditory comprehension who was unaware of his speech production errors when he had to both speak and listen simultaneously. However, when listening to a recording of his speech, he could detect the speech errors he had made. We attribute this patient's unawareness of his speech production errors to a reduced attentional capacity for simultaneous linguistic tasks.

Aged↗