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Biomedical subjects

A Kirk

Publications and source records attributed to A Kirk.

At least 19 recordsLinked to original sources
PubMed1996

A normal bias toward a pictorially defined top in line bisection.

BACKGROUND: We set out to determine whether separable visual and representational components underlie normal subjects' upward and distal biases in bisecting vertical and radial lines under visual guidance. METHODS: Thirty-four normal subjects were asked to bisect lines oriented horizontally, vertically, and radially. Human silhouette figures were placed at either end of each line. These figures were presented upright or upside down in order to pictorially define a "top" to each line independent of the actual top of the visual field. RESULTS: Although subjects erred toward the top of the visual field, they also demonstrated a significant bias toward the heads of the figures for lines in all spatial orientations. CONCLUSIONS: This result supports the existence of two biases: one toward the upper visual field, and another toward an internally represented "top" as suggested pictorially. These findings provide further support for the hypothesis that normal subjects' upward and distal biases on bisection of vertical and radial lines under visual guidance have both representational and visual-based components.

Adult↗
PubMed1994

Unilateral Creutzfeldt-Jakob disease presenting as rapidly progressive aphasia.

A 64-year-old man presented with a three day history of progressive Broca's aphasia, followed within 3 weeks by exclusively right-sided myoclonus, rigidity, and dystonia. Within 4 weeks he was globally aphasic. He died within 7 weeks of onset. In the final week, rigidity and myoclonus became bilateral. CT and MRI were normal. SPECT showed diminished perfusion of the left hemisphere. EEG showed periodic discharges on the left. At autopsy, there were marked cortical spongiform change, neuronal loss, and gliosis throughout the left hemisphere and in the right occipital cortex. Elsewhere in the right hemisphere, spongiform change was non-existent to minimal. There was moderate spongiform change in the molecular layer of the cerebellar cortex, much more marked on the left. Clinical and pathological unilateral cerebral predominance extended to the ipsilateral cerebellum. Creutzfeldt-Jakob disease is an important consideration in patients with rapidly progressive unilateral cerebral signs associated with a movement disorder.

Aphasia, Broca↗
PubMed1994

A representational vertical bias.

We attempted to determine whether separable components underlie normal subjects' upward bias in bisecting vertical and radial lines under visual guidance. Twelve normal subjects indicated the midpoint of visually presented lines oriented vertically, radially, and horizontally. We placed directional labels ("TOP" and "BOTTOM") at either end of each line. Subjects showed significant bias toward the label TOP in horizontal, vertical, and "radial-down" (below eye level) conditions but not in the "radial-up" (above eye level) position. In the horizontal condition, the misbisections actually changed direction depending on whether TOP was to the left or right of midpoint. There were two biases: one toward an internally represented "top" (as suggested by the verbal labels) and another toward the upper visual field. The latter was stronger when the two were opposed. These findings suggest that normal subjects' upward bias on bisection of vertical and radial lines under visual guidance has both representational- and visual field-based components.

Adult↗
PubMed1993

Subcortical contributions to drawing.

Constructional impairment is often considered a sign of cortical damage. However, aphasia, agraphia, and apraxia, disorders traditionally deemed cortical, have been well described following subcortical lesions, suggesting an important role for subcortical structures in cognition. Drawing impairment following subcortical lesions has not been systematically explored or compared with that following cortical damage. We examined relative incidence and severity of drawing impairment after cortical and subcortical strokes and whether there were qualitative differences between these two groups' drawings. Drawings by 125 patients with single hemispheric strokes of similar volume (42 left cortical, 36 left subcortical, 20 right cortical, 27 right subcortical) were compared using a standardized scoring system. Although previously noted right/left differences were confirmed, "subcortical drawings" did not differ from "cortical drawings" on any measures, including overall impairment. Compared with cortical patients, drawing impairment in those with subcortical lesions (especially left) was more strongly associated with impairment of other cognitive abilities. Thus, although a subcortical lesion does not cause more severe drawing impairment, subcortical lesions affecting drawing lead to more widespread cognitive dysfunction than do similarly sized cortical lesions. Drawing impairment often follows subcortical strokes and is by no means an indicator of cortical lesion localization.

Aged↗
PubMed1993

Cardioembolic caudate infarction as a cause of hemichorea in lupus anticoagulant syndrome.

An association exists between antiphospholipid antibodies and chorea. As these antibodies are associated with thrombosis, it has been suggested that cerebral infarction might cause chorea. However, CT and MRI typically do not demonstrate focal basal ganglionic lesions in such patients and an autoimmune mechanism for chorea has also been proposed. We report a young woman with left hemichorea and dyspnea. She was found to have lupus anticoagulant, large aortic and tricuspid vegetations, and pulmonary emboli. CT and MRI showed a small lesion in the head of the right caudate. In the presence of a definite cardiac source for emboli (valvular vegetations) with embolic activity (pulmonary emboli), it is likely that this patient's hemichorea was caused by cardioembolic caudate infarction.

Adult↗
PubMed1991

On drawing impairment in Alzheimer's disease.

Spontaneous drawings of 38 patients, diagnosed by the National Institute of Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria as "probable Alzheimer's disease," and of 39 normal control subjects were analyzed by two independent observers using a standardized scoring system. Drawings of patients with Alzheimer's disease displayed fewer angles, impaired perspective and spatial relations, simplification, and overall impairment compared with those of the control subjects. This represents a combination of the deficits seen following right- and left-hemisphere lesions. Neglect, tremor, and perseveration were not prominent. Drawing impairment was relatively independent of language or memory impairment, but drawing performance was related to perceptual and executive dysfunction in the visuospatial domain. Deterioration was followed up for up to 3 years.

Aged↗
PubMed1991

Dementia with leukoencephalopathy in systemic lupus erythematosus.

Neurologic manifestations, afflicting up to 70% of SLE patients, include psychosis, seizures, chorea, neuropathies, and stroke. MRI is useful in evaluation of lupus patients and several reports have documented cerebral atrophy or focal hyperintensities. We report an unusual MRI appearance in a 56-year-old woman with SLE, diagnosed on the basis of pleuritis, lymphopenia, anti-DNA antibodies, and neurologic involvement. She reported recent onset of Raynaud's phenomenon and generalized macular rash. She presented after two months of gradual deterioration with memory loss, flattened affect, dysphagia, dysarthria, anomia, and somnolence, without focal neurologic signs. Investigations included elevated ESR, reduced complement, normal CSF without oligoclonal bands, negative viral serology, normal hormone and vitamin levels, normal renal and hepatic function. Neuropsychologic testing showed widespread impairment (WAIS-R: FSIQ-63; WMS-69; DRS-98; RCPM-14; WAB AQ-78.8). CT was normal but MRI showed strikingly symmetric, confluent hyperintensities extensively involving cerebral and cerebellar white matter on T1 and T2 weighted scans. Basal ganglia and subependymal and subcortical white matter were spared. Treated with prednisone, the patient made a gradual, but incomplete, recovery. These MRI findings may reflect widespread vasculopathy or direct immunologic brain insult with or without immunologic blood-brain barrier disruption.

Brain Diseases↗
PubMed1991

Auricular myoclonus.

We describe a young man with a two and a half year history of idiopathic irregular contractions of an antitragicus muscle in the absence of a more generalized movement disorder. These contractions persisted in sleep and could not be replicated voluntarily. Because proximal nerve block temporarily eliminated the movements and complex hand movements reduced their amplitude and frequency, we suspect a central generator. However, these movements were not associated with any known pathologic condition.

Adult↗
PubMed1991

Phonolexical agraphia. Superimposition of acquired lexical agraphia on developmental phonological dysgraphia.

Study of neuropsychological sequelae of a focal acquired brain lesion may bring out and help delineate the features of a compensated developmental language disorder and its anatomical substrate. A left-handed man with a history of phonological developmental dyslexia and dysgraphia learned in early adulthood to read and write using a lexical system. Following a small posterior right parietal infarct when aged 56 yrs he developed a severe agraphia displaying features of phonological dysgraphia with impaired segmentation and features of lexical agraphia. Writing was severely impaired for all classes of word and nonword stimuli but his errors did not resemble those attributable to a deficit in the system responsible for the short-term storage of the graphemic representation of a word (graphemic output buffer). These observations imply that an acquired lexical agraphia has been superimposed on his developmental phonological dysgraphia, resulting in a combined or 'phonolexical' agraphia.

Agraphia↗
PubMed1990

Identification of hematopoietic progenitors of macrophages and dendritic Langerhans cells (DL-CFU) in human bone marrow and peripheral blood.

Colonies of cells with distinctive dendritic appearance were observed in methylcellulose cultures of human bone marrow and peripheral blood mononuclear cells (PBMC). Such cells appeared alone in colonies of less than 50 cells, together with macrophages in mixed colonies and also within clusters of T lymphocytes at high culture cell numbers. The morphologic resemblance to lymphoid dendritic cells was confirmed by electron microscopy and the cells were distinguished from macrophages by immunoenzymatic and immunogold labeling with monoclonal antibodies (MoAbs). Like macrophages they were HLA-DR+ and CD4+. However, they lacked nonspecific esterase and the macrophage cytoplasmic marker Y1/82A. Most strikingly, cells were strongly HLA-DQ+ and expressed CD1a (T6), which is characteristic of skin Langerhans cells. Their functional similarity to lymphoid dendritic cells was demonstrated by their ability to stimulate allogeneic mixed leukocyte reactions. Dendritic cell colony numbers were estimated in both bone marrow and peripheral blood of controls and in leukemia and lymphoma patients before and after chemotherapy. Colony numbers were low in control blood and in patients before treatment (less than 1.0 to 3.7/10(5) cells). However, during hematopoietic recovery the mean value increased to 37.5/10(5) cells and this increase correlated closely with the observed increase in circulating colony forming unit-granulocyte macrophage (CFU-GM) in individual patients. Autoradiographic studies demonstrated mitotic activity within CD1a+ colonies and a linear relationship between cultured cells and both pure and mixed colonies was consistent with their derivation from a single precursor. These data indicate that a novel hematopoietic progenitor of dendritic/Langerhans cells (DL-CFU) may now be identified in a clonal assay system and suggest a probable common progenitor for these cells and macrophages.

Antibodies, Monoclonal↗
PubMed1989

Hemispheric contributions to drawing.

The drawings of 69 consecutive stroke patients with single cerebral lesions on CT and of 33 normal controls, were analyzed by two independent observers using a standardized scoring system. The drawings of left brain damaged subjects (LBD) were more impaired overall than those of right brain damaged subjects (RBD). RBD drawings displayed hemispatial neglect and impaired spatial relationships. LBD drawings were simplified and exhibited low level errors of execution. Lesion size correlated significantly with drawing impairment in RBD but not in LBD. No relationship between intrahemispheric lesion location and drawing quality was found. However, severity of hemiparesis correlated significantly with drawing impairment in LBD. Performance on a visuospatial perceptual task correlated better with overall drawing quality for RBD than for LBD. Our data suggest that neglect and a visuospatial deficit impair drawing in RBD while dominant hand paresis and a conceptual impairment which parallels comprehension impairment contribute to LBD drawing disability.

Aged↗
PubMed1989

The recovery of circulating progenitor cells after chemotherapy in AML and ALL and its relation to the rate of bone marrow regeneration after aplasia.

Peripheral blood levels of BFU-e, CFU-GM and CFU-mix were studied serially in nine patients with acute leukaemia in remission during the period of recovery that followed induction or consolidation chemotherapy. Following 23 courses of treatment in the nine patients, the values for all three classes of progenitor were found to be higher in ALL than in AML (mean peak CFU-GM levels 5.8 x 10(3)/ml and 0.8 x 10(3)/ml respectively) and the highest levels were observed in patients recovering the most rapidly from bone marrow aplasia. Peak levels of these progenitors correlated best with the rate and extent of platelet recovery and all patients achieving blood levels of greater than 1.0 x 10(3) CFU-GM/ml had recovered greater than 100 x 10(9)/l platelets by 20 d and had peak platelet counts of greater than 400 x 10(9)/l within 40 d following chemotherapy. The peak values for circulating progenitors fell markedly after repeated courses of treatment in three of the five AML patients studied and this is likely to limit useful harvesting of such cells during later consolidation courses in this disease.

Adolescent↗
PubMed1989

Ranitidine fails to suppress the growth in vitro of haemopoietic progenitors from human peripheral blood or bone marrow.

Ranitidine was added in various concentrations (25-1600 ng/ml) to clonal assays of haemopoietic progenitors of normal human peripheral blood or bone marrow. Although a significant reduction in colonies forming from granulocyte-macrophage progenitors (CFU-GM) was demonstrated at the lowest drug concentration, no significant growth suppression was seen at higher concentrations. There was no evidence for growth inhibition of either erythroid progenitors (BFU-E) or pluripotent progenitors (CFU-mix) at any of the drug concentrations studied. A direct toxic effect of ranitidine on normal haemopoietic progenitors thus appears an unlikely cause of cytopenias observed during treatment.

Bone Marrow Cells↗
PubMed1989

The prediction of violent behavior during short-term civil commitment.

The predictive validity of the clinical judgment of dangerousness in the context of short-term civil commitment was studied prospectively by comparing the behavioral scale ratings of both verbal and physical aggression between 37 persons committed on the basis of "danger to others" versus 31 persons committed on other grounds. No statistically significant difference was found between these two groups of detainees with regard to the levels of aggression measured during their approximately three-day detention. This finding is in agreement with abundant previous research which documents the inability of psychiatrists to accurately predict future dangerousness, prompting the author to suggest that the "dangerousness" criterion for civil commitment be rejected. Although society is unlikely to resurrect the broadly defined "in need of treatment" criterion because of its historically demonstrated ever present potential for abuse, the author suggests an alternative criterion for civil commitment which, in perhaps a more well-defined and more practical way, would allow the state to maintain its doctrine of parens patriae toward mental patients.

Adult↗