Adenosine deaminase in pericardial fluids. Which test is best?
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Adenosine Deaminase↗
Biomedical subjects
K D Miller
Publications and source records attributed to K D Miller.
Models of activity-dependent neural development.
What makes a useful model of neural development? One important contribution of modeling is to demonstrate that proposed biological mechanisms can be sufficient to account for experimental results. The Von der Malsburg model is a classic example. But such demonstrations alone do not provide tools to experimentally distinguish one mechanism from another. To draw such distinctions, the connection between measurable biological quantities and developmental outcomes must be established. Perhaps the most important task for the future of developmental modeling is to deepen the connection between theory and experiment. Experimentally, this requires detailed and difficult measurements or experimental perturbations of the correlations among inputs and the intracortical connectivity existing during development. Simultaneous measurement of the maps of spatial phase and orientation of mature simple cells will provide important information for the understanding of orientation column development. Theoretically, the number of open problems is enormous. How will inclusion of additional plasticity mechanisms, such as sprouting and retraction of synapses or plasticity of intracortical connections, alter the analytical understanding thus far achieved? What precisely determines the width of orientation columns in the model presented here? Can the relationship between ocular dominance and orientation columns be understood from developmental rules in a testable way? The existing framework may be extended to a three-dimensional cortex and to more complex models of intracortical connectivity. It may also be applied to other developmental phenomena including the development of lamination in the LGN (Shatz and Stryker, 1988; Hahm et al., 1991), the formation of visual maps in experimentally altered auditory cortex (Roe et al., 1990, 1992), and the mapping of visual and auditory maps in the optic tectum (Knudsen and Brainard, 1991; Brainard and Knudsen, 1993). For each system the goal is to develop testable predictions as to the patterns of activity and connectivity that could or could not lead to the results observed given a proposed mechanism of plasticity. Incorporation of deeper levels of biophysical realism will extend, deepen, and perhaps fundamentally alter the framework presented here. An important goal for the future will be to understand the computational and functional significance of developmental rules. Activity-dependent, competitive mechanisms of synaptic plasticity appear to play an important role in many processes of late neural development, where an initially rough connectivity pattern refines to a precise, mature pattern. A prominent example is the formation of ocular dominance columns in the visual cortex of many mammals. These processes may be modeled at several levels.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Hodgkin's disease: impact on childbearing.
Although Hodgkin's disease is considered one of the "curable" cancers, the high cure rates associated with this disease are not accomplished without risk of potentially severe, immediate, and late side effects. Because the predominant histologic subtype of Hodgkin's disease found in the United States generally affects the 15- to 25-year-old age group, the disease, its treatment, and the side effects of treatment will affect many women of childbearing age. The treatment and its effects on the patient and offspring, including posttreatment fertility, are key issues for perinatal nurses.
Adolescent↗
One normal angiogram is not always diagnostic after subarachnoid hemorrhage: case report and review of the literature.
How many angiograms should be obtained after subarachnoid hemorrhage if the first one fails to identify an aneurysm? We recently encountered this common clinical problem: a patient with subarachnoid hemorrhage confirmed by computed tomography required three angiograms to identify an aneurysm at the posterior communicating artery. Review of the literature reveals conflicting recommendations as to proper management of this common and sometimes perplexing problem. Decision-making must be applied on a case-by-case basis, but persistence is probably warranted when the index of suspicion is high.
Adult↗
A model for the development of simple cell receptive fields and the ordered arrangement of orientation columns through activity-dependent competition between ON- and OFF-center inputs.
Neurons in the primary visual cortex of higher mammals respond selectively to light/dark borders of a particular orientation. The receptive fields of simple cells, a type of orientation-selective cell, consist of adjacent, oriented regions alternately receiving ON-center and OFF-center excitatory input. I show that this segregation of inputs within receptive fields can occur through an activity-dependent competition between ON-center and OFF-center inputs, just as segregation of inputs between different postsynaptic cells into ocular dominance columns appears to occur through activity-dependent competition between left-eye and right-eye inputs. These different outcomes are proposed to result, not from different mechanisms, but from different spatial structures of the correlations in neural activity among the competing inputs in each case. Simple cells result if ON-center inputs are best correlated with other ON-center inputs, and OFF with OFF, at small retinotopic separations, but ON-center inputs are best correlated with OFF-center inputs at larger separations. This hypothesis leads robustly to development of simple cell receptive fields selective for orientation and spatial frequency, and to the continuous and periodic arrangement of preferred orientation across the cortex. Input correlations determine the mean preferred spatial frequency and degree of orientation selectivity. Estimates of these correlations based on measurements in adult cat retina (Mastronarde, 1983a,b) produce quantitative predictions for the mean preferred spatial frequencies of cat simple cells across eccentricities that agree with experiments (Movshon et al., 1978b). Intracortical interactions are the primary determinant of cortical organization. Simple cell spatial phases can play a key role in this organization, so arrangements of spatial phases and preferred orientations may need to be studied together to understand either alone. Possible origins for other cortical features including spatial frequency clusters, afferent ON/OFF segregation, blobs, pinwheels, and opponent inhibition within simple cell receptive fields are suggested. A number of strong experimental tests of the hypothesis are proposed.
Algorithms↗
Impact of axillary lymph node dissection on the therapy of breast cancer patients.
PURPOSE: We studied a series of 283 breast cancer patients retrospectively to determine the actual benefits of axillary lymph node dissection (ALND) for these patients. PATIENTS AND METHODS: The records of 283 women with invasive breast cancer treated between 1988 and 1990 were reviewed for histologic status of the axillary lymph nodes, tumor size, DNA content, hormone-receptor values, and actual adjuvant treatments received. RESULTS: ALND was of possible therapeutic benefit for the 15% (43 of 283) of patients who had clinically positive nodes. Nodal metastases were found in 86% (37 of 43) of patients in this subgroup. ALND alone determined the indication for standard adjuvant therapy for a group of 31% (88 of 283) of patients who had favorable primary biopsy findings and clinically negative axillary nodes; ALND proved that 13% (11 of 88) of these latter patients had positive nodes. For 54% (152 of 283) of patients who had clinically negative nodes and unfavorable biopsies, ALND played no role in the decision as to whether standard adjuvant therapy was indicated. Only 5% (seven of 152) and 3% (four of 152) of these latter patients received radiation therapy and/or high-dose adjuvant chemotherapy, respectively, because of ALND. CONCLUSION: The benefits of ALND vary greatly for different groups of breast cancer patients, and controlled studies may be needed to determine whether ALND is necessary for all breast cancer patients.
Adult↗
Peroxidase labelling immunocytochemistry: a comparison of eleven commercially-available avidin-biotin systems.
Eleven commercially produced avidin-biotin peroxidase labelling systems employed in immunocytochemistry were compared by titrating a monoclonal and a polyclonal antibody onto routinely prepared formalin-fixed paraffin wax sections of tonsil and appendix. The cost per test for each labelling system was also calculated.
Avidin↗
Metastatic pigmented neuroectodermal tumor with cranial CT-pathology correlation.
Pigmented neuroectodermal tumors are a relatively rare clinicopathologic entity, presenting in a variety of locations. Their histogenesis suggests a transformation from common pleuripotential neural crest cells with varying degrees of differentiation to neural elements and melanocytes. We present a case of just such a tumor, which presented initially in the mandible of a leukemic patient who received irradiation to the skull base, as well as systemic chemotherapy, for suspected cranial leukemic involvement. Subsequent development of intracranial spread was documented both by imaging and pathology. Extracranial spread was also found at autopsy. This unusual presentation and widespread dissemination of the neuroectodermal tumor in our case confirms its aggressiveness and potential for multifocality.
Acute Disease↗
Cine magnetic resonance imaging of the temporomandibular joint.
Magnetic resonance imaging (MRI) provides a significant amount of information about both the position of the meniscoligamentous complex and the osseous structures in evaluation of internal derangements of the temporomandibular joint (TMJ). With the advent of computer-driven cine displays, dynamic information is now available, providing cost-effective diagnostic evaluation similar to cine fluoroscopy with arthrography, but without the ionizing radiation exposure or discomfort. Using a bite block, a series of sagittal images are obtained with the patient "posing" at different degrees of jaw opening. The subsequent cine MRIs with "posed" motion are striking and very helpful in evaluating various types of TMJ dysfunction. At the authors' institution, 205 patients were examined with a history of TMJ arthralgia. Correlation of imaging studies and surgical findings reveals a sensitivity (98%) and specificity (96%) for identifying the meniscoligamentous complex.
Adolescent↗
Development of orientation columns via competition between ON- and OFF-center inputs.
Development of orientation-selective receptive fields in primary visual cortex of higher mammals can occur through activity-dependent competition between ON-center and OFF-center inputs. This competition yields orientation and spatial-frequency-selective 'simple cells' if the dark activity of ON (or OFF)-center inputs is best correlated with that of other ON (or OFF)-center inputs at small retinotopic separations and with that of OFF (ON)-center inputs at larger separations. Features of cat and monkey cortical organization emerge, including continuous and periodic arrangement of preferred orientation across the cortex. A new feature, systematic variation of receptive field spatial phase, is predicted. Experimental tests of this hypothesis are proposed.
Animals↗
AUA1: new immunocytochemical marker for detecting epithelial cells in body cavity fluids.
Further to detailed genetic and biochemical characterisation of AUA1 as a surface glycoprotein present on epithelial cells, the antibody against AUA1 was used as an immunocytochemical marker of epithelial cells in body cavity fluids in an attempt to improve the diagnosis made on routine staining. AUA1 was initially tested in 144 morphologically clear cut effusions. It was positive in 46 of 52 (88%) carcinomas and negative in 82 of 84 (98%) benign effusions, including technically inadequate or poorly cellular preparations. There were no false positive results. AUA1 was subsequently used more selectively--that is, in 42 of 175 (24%) of morphologically difficult fluids. AUA1 provided essential diagnostic information in 15 of 42 (36%) and confirmed diagnosis in 17 of 42 (40%), thus enabling accurate diagnosis in a further 32 of 42 (76%) of the difficult cases. The total diagnostic accuracy was therefore 94.3%. AUA1 is a reliable immunocytochemical marker for detecting epithelial cells in body fluids. Its use improves diagnostic accuracy of morphological assessment in difficult cases.
Antibodies, Monoclonal↗
Compulsive overeating.
Compulsive overeating is a behavior used in an attempt to numb or nurture feelings that are threatening to the person. Emotional states are soothed by use of food. Treatment is designed to respond to internal, biologic causes of hunger and satiety while simultaneously allowing feelings to surface and be dealt with. Work on the inner child enables the person to identify and deal with unmet needs and correct distortions from childhood. The secondary gain realized from the extra weight is examined, and direct means of dealing with these needs explored. The focus of recovery is on learning to nurture the self, physically and emotionally.
Body Image↗
Body-image therapy.
Body image is a complex interplay of factors resulting in a sense of the body perceived by that individual. In eating-disorder clients, there is a distortion between their perceived image of their body and its actuality. This is combined with a sense of dissatisfaction and alienation of mind and body. Cognitive, right-brain, and kinesthetic strategies are described that seek to decrease distortion and dissatisfaction and facilitates individuation-separation and a reintegration of the self. These strategies are both therapeutic and evaluative. Cultural expectations of women have had a profound impact on the proliferation of eating disorders, and they account for the fact that body distortion is found in both normal and eating-disordered women.
Body Image↗
Experimental and theoretical studies of the organization of afferents to single orientation columns in visual cortex.
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Afferent Pathways↗
Ocular dominance column development: analysis and simulation.
The visual cortex of many adult mammals has patches of cells that receive inputs driven by the right eye alternating with patches that receive inputs driven by the left eye. These ocular dominance patches (or "columns") form during early life as a consequence of competition between the activity patterns of the two eyes. A mathematical model of several biological mechanisms that can account for this development is presented. Analysis of this model reveals the conditions under which ocular dominance segregation will occur and determines the resulting patch width. Simulations of the model also exhibit other phenomena associated with early visual development, such as topographic refinement of cortical receptive fields, the confinement of input cell connections to patches, monocular deprivation plasticity including a critical period, and the effect of artificially induced strabismus. The model can be used to predict the results of proposed experiments and to discriminate among various mechanisms of plasticity.
Afferent Pathways↗
Treatment of severe malaria in the United States with a continuous infusion of quinidine gluconate and exchange transfusion.
During the past decade the incidence of Plasmodium falciparum malaria in the United States has increased 10-fold. Treatment may be delayed because the therapy recommended for severe or complicated disease, intravenous quinine dihydrochloride, is available only from the Centers for Disease Control. We studied 17 patients who were treated for severe or complicated P. falciparum malaria in the United States between 1985 and 1987. Five patients were treated with a continuous infusion of quinidine gluconate, 10 with an exchange transfusion in addition to the continuous infusion of quinidine gluconate, and 2 with intermittently administered intravenous quinine dihydrochloride and an exchange transfusion. All 16 patients with P. falciparum malaria (1 patient had P. vivax malaria) had hyperparasitemia at the time of diagnosis (6 to 54 percent of the erythrocytes infected; median, 13 percent). Three patients with marked hyperparasitemia (54, 38, and 30 percent) and multiple other indicators of a poor prognosis, including advanced age, died. The 13 patients who completed their courses of quinidine with or without exchange transfusion had a parasitemia level of 1.1 percent or less 28 to 72 hours (mean, 44.4 hours) after the start of therapy. Side effects of quinidine treatment were observed in only two patients, one of whom had a serum quinidine concentration above the toxic level. We conclude that the continuous infusion of quinidine gluconate is well tolerated alone and with exchange transfusion and is effective in the treatment of severe and complicated malaria.
Adult↗
An animal model of hearing loss from alpha-difluoromethylornithine.
alpha-Difluoromethylornithine is a new antineoplastic and antiparasitic drug that inhibits the synthesis of polyamines. It causes a sensorineural hearing loss in humans. We have established an animal model for alpha-difluoromethylornithine-induced hearing loss. The time course for onset and recovery of the hearing loss in animals was similar to that seen in humans. Electrophysiologic and histologic data suggest that the anatomic site of alpha-difluoromethylornithine-induced hearing loss is the organ of Corti. Unlike other drugs with ototoxic effects, the specific enzymatic site of action of alpha-difluoromethylornithine is known, making it a potentially important tool in auditory research.
Animals↗
Visual responses in adult cat visual cortex depend on N-methyl-D-aspartate receptors.
We have investigated the role of the N-methyl-D-aspartate (NMDA) receptor, a subtype of glutamate receptor, in the responses of cells in adult cat visual cortex. After intracortical infusion of the NMDA receptor antagonist DL-2-amino-5-phosphonovalerate (DL-APV) for one day, iontophoretic responses to NMDA, to kainate, and to quisqualate revealed a receptor blockade specific to NMDA receptors and extending several millimeters from the cannula. In this region, neuronal responses to visual stimulation were profoundly suppressed, in a manner strongly correlated with the degree of NMDA receptor blockade. Neither NMDA receptor blockade nor activity suppression was caused by the inactive stereoisomer L-APV. Hence, we conclude that NMDA receptors make a major contribution to normal excitatory transmission in adult visual cortex.
2-Amino-5-phosphonovalerate↗