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Biomedical subjects

D H Jacobs

Publications and source records attributed to D H Jacobs.

At least 19 recordsLinked to original sources
PubMed1998

Recovery following lateral medullary infarction.

Lateral medullary infarction (LMI) has a well-defined clinical syndrome and vascular pathology. The functional outcome and degree of disability of patients with LMI, however, have not been as well investigated. We followed 18 consecutive patients with LMI during inpatient stroke rehabilitation. Thirteen patients were followed after discharge from the hospital over a mean time of 1 year. The degree of disability on admission and discharge from the hospital, and at follow-up was assessed using the motor component of the Functional Independence Measurement (FIM-motor). All patients were discharged home. During inpatient rehabilitation, the functional performance of all patients improved substantially from FIM-motor 50.9 +/- 13.0 (mean +/- SD) on admission to 76.9 +/- 10.5 at discharge. Patients with lower FIM-motor scores on admission had more functional improvement from admission to discharge than those with higher FIM-motor scores on admission. Patients with disease of the posterior inferior cerebellar artery showed significantly less functional improvement than patients with disease of the vertebral artery or no identified vascular pathology in the posterior circulation. In the follow-up group, the FIM-motor scores further improved to 84.6 +/- 8.4, indicating nearly full functional independence. Eighty-five percent were totally independent with ambulation. Five of seven previously working patients returned to work. Patients with LMI have few functional deficits after completion of inpatient rehabilitation, continue to improve functionally after discharge, and often resume their previous activities.

Adult↗
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

Adynamic aphasia: a transcortical motor aphasia with defective semantic strategy formation.

Adynamic aphasia is a form of transcortical motor aphasia characterized by sparse but otherwise normal spontaneous speech that may improve when concepts are introduced by external stimuli. Akinesia, impaired concept formation, inertia of concept generation, a defective semantic network, damage or impaired access to the verbal output lexicon, and defective semantic strategy formation have been proposed to account for this disorder. We studied a patient with adynamic aphasia and frontal lobe systems dysfunction due to bilateral striatocapsular infarctions. The patient was not akinetic but did demonstrate inertia of concept generation that could be overcome with prompting. However, prompting did not improve the number of concepts generated. He demonstrated a generally intact verbal lexicon and semantic network and normal lexical priming. However, his ability to sort closely related items into different classes without prior cuing regarding the nature of the classes was defective. Although his verbal memory was normal, he appeared to use a serial rather than a semantic strategy to recall items. Finally, despite normal lexical priming, he was impaired on a letter fluency task. These results most clearly demonstrate a defect in semantic strategy formation but indicate an additional and possibly related deficit in concept formation and a partial deficit in lexical strategy formation. All of these deficits appear to reflect impairment in the hierarchical organization of knowledge specific to the task at hand. This appears to be a key component of executive functions supported by frontal lobe systems.

Aphasia↗
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↗
PubMed1997

Intracranial angioplasty: experience and complications.

PURPOSE: To review our experience with intracranial angioplasty, including the complications we encountered. METHODS: During a 3-year period, from 1993 to 1996, 10 patients had intracranial percutaneous transluminal angioplasty (PTA). The stenosed vessels included three internal carotid arteries, one middle cerebral artery, one basilar artery, and five vertebral arteries. Stenosis in all patients was 75%, or greater. PTA was technically successful in eight patients; in two patients it could not be performed owing to inability to traverse the stenosed area. RESULTS: Two patients had successful and uneventful PTA. Five patients had vasospasm, which resolved with local vasodilators in two and with repeat PTA in one. Vasospasm led to stroke in two patients. Compromise of perforating vessels and arterial dissection were associated with stroke in two patients. CONCLUSION: Intracranial PTA is technically feasible but associated with risks related to vasospasm, arterial trauma, and compromise of perforating vessels.

Adult↗
PubMed1995

Right-left confusion in Gerstmann's syndrome: a model of body centered spatial orientation.

Gerstmann's syndrome encompasses the tetrad of finger agnosia, agraphia, acalculia and right-left confusion and is associated with lesions of the dominant angular gyrus. The localizing value of this syndrome has been questioned because multiple mechanisms can account for each of the components of the syndrome. We present the case of a man who developed Gerstmann's syndrome following a focal infarct of the left angular gyrus. The patient's right-left confusion could not be accounted for by either an aphasia or a degraded body schema. A series of experiments that investigated the patient's spatial mapping system by progressively restricting the degrees of freedom for spatial rotation revealed an isolated defect in deriving the relative position of an object along the horizontal axis. Defective horizontal mapping can account for the other components of Gerstmann's syndrome because they all share a common dependency on relative horizontal positioning.

Aged↗
PubMed1995

Neglect of radial and vertical space: importance of the retinotopic reference frame.

Neglect from bilateral brain injury can disrupt responses along space defined by the vertical and radial axes. The spatial reference frames for vertical and radial neglect remain largely undefined, however. The viewer centred system, for example, consists of retinocentric and cephalocentric/corporacentric frames. In the present study, different viewer centred reference frames were dissociated in a patient with combined far radial superior vertical neglect through performance of radial line bisections above and below eye level. To separate reference frames for vertical space, bisections were performed while the patient was lying sideways. Results suggest that this patient's neglect respected a retinotopic viewer centred reference frame.

Adult↗
PubMed1995

Impaired perception of facial identity and facial affect in Huntington's disease.

We tested five patients with Huntington's disease on tasks of facial discrimination and facial affect discrimination and matching. Four patients were impaired on a task or tasks of face discrimination, and all patients were impaired on at least one task of facial affect discrimination. We suggest that these findings reflect the role of the basal ganglia or its connections in visual processing.

Adolescent↗
PubMed1995

Emotional facial imagery, perception, and expression in Parkinson's disease.

Patients with Parkinson's disease (PD) may be impaired at expressing emotional faces and perceiving emotional facial affect. We tested the hypothesis that patients with PD may be impaired at imaging emotional faces. We first compared 12 patients with PD and 30 control subjects on perceptual and imagery tasks. Patients were significantly impaired on a task of emotional facial imagery but not on a control task of object imagery. Patients were also impaired on a task of perceiving emotional faces. Subsequently, we found that PD patients were impaired relative to controls on making emotional faces. Performance on both the perceptual and motor tasks of facial expression significantly correlated with performance on the emotional facial imagery task. We suggest that the basal ganglia, together with the right hemisphere, are part of a neural network subserving emotional facial tasks.

Aged↗
PubMed1994

Anosognosia for hemiplegia: an electrophysiologic investigation of the feed-forward hypothesis.

The cause of anosognosia for hemiplegia (AHP) remains unclear. Weakness is detected when there is a mismatch between the expectancy of movement and the sensory perception of movement. The feed-forward hypothesis of AHP posits that there is a failure of detection because there is a loss of motor intention and expectancy of movement. We tested motor intention by measuring the activation of proximal muscles (pectoralis majoris) while subjects squeezed a dynamometer with each hand. We tested a group of normal controls, a group of patients with hemiparesis, a patient with neglect, a patient with resolved AHP, and a patient with persistent AHP. The patient with AHP did not contract either of his pectoralis muscles when asked to squeeze with his contralesional, paretic hand, yet he contracted both of them when squeezing the dynamometer with his ipsilesional hand. Normal controls, hemiparetic controls, and the patient with hemispatial neglect contracted both pectorales when asked to squeeze with each hand. The pattern of activation seen in the patients with persistent AHP and resolved AHP demonstrates a loss of motor intention and lends support to the feed-forward hypothesis of AHP.

Agnosia↗
PubMed1992

Meningiomas are not significantly associated with breast cancer.

We studied 283 meningiomas seen at the University of Kansas, Kansas City, from 1948 through 1984, identifying all additional nonmeningeal malignancies and primary brain tumors in these patients and calculating the expected number of additional tumors by the use of a person-year method from age and sex-matched cancer incidence data. We determined expected numbers of total neoplasms in our meningioma population as well as the expected numbers in each major organ system for the sexes independently and together. We then calculated standard morbidity ratios and 95% confidence intervals for each tumor type. The number of breast cancers did not reach statistical significance. We found a significantly increased number of second primary brain tumors in women (standard morbidity ratio, 8.0; 95% confidence interval, 2.2 to 20.4) and an increased number of thyroid cancers in both sexes (standard morbidity ratio, 7.5; 95% confidence interval, 1.5 to 21.9).

Adult↗
PubMed1990

Matrix vesicle biogenesis in vitro by rachitic and normal rat chondrocytes.

Calcifying matrix vesicles (MVs) are released from chondrocytes and osteoblasts in monolayer culture. In the present studies, we tested the ability of rachitic versus normal rat growth plate chondrocytes in micromass or monolayer primary cultures to produce MVs. Unlike earlier reports of in vitro MV biogenesis by chicken chondrocytes in which most MVs were released into the medium, we found that most of the released rat matrix vesicles were entrapped in a newly formed cartilaginous matrix enveloping the cells. These matrix-associated MVs could be isolated by mild collagenase treatment and concentrated by differential centrifugation. Vesicle production slowed in the older 2- to 4-week-old cultures and, unlike vesicle release from cultured chicken chondrocytes, active vesicle production did not show a second burst of activity at 3 to 4 weeks. Alkaline phosphatase (ALP) activity diminished with time in culture in cells and matrix vesicles, suggesting a decrease in differentiative expression. Protein profiles on SDS polyacrylamide gels of native matrix vesicles and culture-derived MVs from rachitic and normal cells were quite similar and showed a typical simplified protein pattern as compared to chondrocyte plasma membrane proteins. There were distinctive proteins migrating at 130, 80 to 95, 66, 43, 20, and 14 kd. Culture-derived MVs showed vigorous in vitro calcifying activity that was ALP related. We conclude that 1) rachitic chondrocytes are essentially normal in their matrix vesicle production; 2) matrix entrapment of MVs is a characteristic of rat chondrocyte cultures; and 3) culture-produced MVs are similar to native MVs in protein profile and calcifiability, and thus can be studied as a model for normal MV composition and calcification.

Animals↗
PubMed1987

Female patients with meningioma of the sphenoid ridge and additional primary neoplasms of the breast and genital tract.

Of 283 meningioma patients seen at the University of Kansas from 1948 to 1984, eight women acquired two primary extraneural cancers in addition to their meningiomas. Of these eight patients, six (75%) had sphenoid ridge meningiomas compared with 15% of meningioma patients overall (P less than 0.001). Seven (87.5%) had at least one breast or genital cancer (P less than 0.001). Of the six with sphenoid ridge meningiomas, five (83.3%) had both of their additional tumors in these two organ systems, and the sixth had one such tumor. It is proposed that this grouping of sphenoid ridge meningioma, breast cancer, and genital cancer represents a unique constellation of neoplasms in women.

Adult↗
PubMed1986

T cell-induced expression of membrane IgG by 70Z/3 B cells.

To study T cell regulation of B cell isotype differentiation, we determined the capacity of clonal T cell populations (hybridomas derived by fusing BW5147 with Con A-activated Peyer's patch (PP) and spleen T cells) to induce "downstream" isotype expression by the pre-B cell lymphoma 70Z/3. In initial studies, we found that 70Z/3 B cells cultured in the presence of LPS (1 microgram/ml) expressed membrane IgM (mIgM) but not membrane IgG (mIgG). In contrast, 70Z/3 B cells cultured with HAJ-3 T cells, a PP-derived T cell hybridoma (as well as other similarly derived PP and spleen hybridomas), or with HAJ-3 T cells plus LPS do express mIgG. Such expression occurred in spite of mitomycin C-induced blockage of cell proliferation, and is observed in 70Z/3 B cell subclones cultured with HAJ-3 T cells. For these reasons, it is not due to selective expansion of a small pre-switched mIgG-bearing 70Z/3 B cell subpopulation. In other studies it was shown that 70Z/3 B cells expressing mIgG after induction by HAJ-3 T cells continue to express mIgM and do not secrete IgG. Finally, exposure of 70Z/3 B cells to the macrophage factor IL 1 and the T cell factors IL 2, BSF-pl, and BCGF-II present in EL-4 cell supernatants did not result in mIgG expression. On the basis of these studies, we conclude that a clonal B cell population expressing mIgM can be induced by T cells to co-express mIgG. Because the B cells do not express mIgG unless exposed to T cells, this represents a T cell-induced isotype switch.

Animals↗