Biomedical subjects
J Dunne
Publications and source records attributed to J Dunne.
The role of learning in remembered duration.
In two experiments, the effects of learning on both the accuracy and bias of duration judgments were examined. In Experiment 1, subjects learned one of two tasks (i.e., using a computer software package, building a model car), containing a varying number of action steps, over a one-, three-, or five-trial period. Retrospective judgments of a task's total duration revealed that accuracy was high at intermediate stages of learning but was low at early stages due to an overestimation bias and low at later stages due to an underestimation bias. The number of action steps within a task influenced behavior only at early learning stages where more action steps led to significantly longer duration estimates. Experiment 2 acted as a converging operation in which novice and experienced pianists were asked to estimate, in advance, how long they thought it would take them to play melodies that varied in their degree of familiarity (i.e. recently learned, well learned, extremely well learned). When these estimates were compared with the melodies' actual playing times, results revealed a similar pattern of accuracy and bias as found in Experiment 1. These findings are discussed in terms of a "structural remembering model" that emphasizes the role of event predictability in time estimation behavior.
Pilot-controlled trial of the extracorporeal liver assist device in acute liver failure.
The objective of this pilot controlled study was to evaluate the extracorporeal liver assist device (ELAD) in patients with acute liver failure who were judged to still have a significant chance of survival (approximately 50%) and in those who had already fulfilled criteria for transplantation. Twenty-four patients were divided into two groups, 17 with a potentially recoverable lesion (group I) and 7 listed for transplantation (group II), and then randomly allocated to ELAD haemoperfusion or control. The median period of ELAD haemoperfusion was 72 hours (range 3-168 h). Biocompatibility of the device was good, with no acceleration in platelet consumption, and haemodynamic stability was maintained. Two patients were withdrawn from the study because of worsening of preexisting disseminated intravascular coagulation in one case and a hypersensitivity reaction in the other. Deterioration with respect to encephalopathy grade was more frequent in the control patients, 7 of 12 (58%), than in the ELAD-treated patients, 3 of 12 (25%). In group I where survival for the ELAD cases was 7 of 9 (78%), there was a higher than expected survival in the controls, 6 of 8 (75%). For group II cases, survival was 1 of 3 (33%) for the ELAD-treated patients, and 1 of 4 (25%) for the controls. Both of the survivors underwent transplantation. Assessment of additive function for the device revealed an improvement in galactose elimination capacity after 6 hours of haemoperfusion. Based on the results of this pilot-controlled trial, better indices of prognosis will be required, in addition to those used to select for transplantation, if patients at an earlier stage of clinical deterioration are to be included in future studies.
Steroids for intubated croup masking airway haemangioma.
Recently, the beneficial role of steroids for acute laryngotracheobronchitis has been more clearly defined for both intubated and unintubated patients. However, corticosteroids also improve the clinical signs of airway haemangiomata. Two patients are described who illustrate how this can be a source of diagnostic confusion.
Beta-2-microglobulin, neopterin and monocyte Fc gamma receptors in opportunistic infections of HIV-positive patients.
The aim of this study was to examine serum and cellular markers of immune activation in HIV-positive (HIV+) patients with and without current opportunistic infections. Fc gamma receptor (Fc gamma R) expression on monocytes, serum neopterin and beta-2-microglobulin were studied. Thirty HIV+ patients (grouped according to Centers for Disease Control (CDC) classification) were studied and compared with 27 normal blood donor controls. HIV+ patients were further separated into three groups: 2 (CDC II), 3 (CDC III/IV without infections) and 4 (CDC III/IV with current infections). Eleven of the patients had current opportunistic infections. Results indicate that beta-microglobulin, neopterin, fc gamma RI, Fc gamma RII and Fc gamma III were significantly increased in HIV+ patients compared to controls. Further analysis of the data using Tukey-Kramer all pairwise comparison revealed that for beta-2-microglobulin the mean values for patients in groups 2, 3 and 4 were significantly different (P < 0.0001). Serum neopterin levels and the percentage of CD14+14+ monocytes expressing Fc gamma RIII showed significant differences in the mean values of group 2 and group 4; similarly, for CD4+ lymphocyte counts group 2 and group 4 were significantly different. These results indicated that beta-2-microglobulin, neopterin and CD14+ monocyte Fc gamma RIII are increased particularly in HIV+ patients with current opportunistic infections while CD4+ lymphocyte counts are reduced. The results suggest that these markers, particularly beta-2-microglobulin, could be useful indicators of the inflammatory process associated with opportunistic infection at later stages of disease where other laboratory markers may be atypical.
Molecular cloning and tissue expression of FAT, the human homologue of the Drosophila fat gene that is located on chromosome 4q34-q35 and encodes a putative adhesion molecule.
FAT, a new member of the human cadherin super-family, has been isolated from the T-leukemia cell line J6. The predicted protein closely resembles the Drosophila tumor suppressor fat, which is essential for controlling cell proliferation during Drosophila development. The gene has the potential to encode a large transmembrane protein of nearly 4600 residues with 34 tandem cadherin repeats, five EGF-like repeats, and a laminin A-G domain. The cytoplasmic sequence contains two domains with distant homology to the cadherin catenin-binding region. Northern blotting analysis of J6 mRNA demonstrated full-length, approximately 15-kb, FAT message in addition to several 5'-truncated transcripts. In addition to its presence in J6 cells, in situ hybridization revealed FAT mRNA expression in epithelia and in some mesenchymal compartments. Furthermore, higher levels of expression were observed in fetal, as opposed to adult, tissue, suggesting that its expression may be developmentally regulated in these tissues. FAT shows homologies with a number of proteins important in developmental decisions and cell:cell communication and is the first fat-like protein reported in vertebrates. The gene encoding FAT was located by in situ hybridization on chromosome 4q34-q35. We propose that this family of molecules is likely to be important in mammalian developmental processes and cell communication.
No more cause for neglect. Introducing a nutritional assessment tool and action plan.
Research points to unacceptably high rates of malnutrition in hospital patients. An assessment tool and action plan were devised, based on the Waterlow system, to help nurses quickly identify and take steps to overcome this problem in a structured way.
Botulinum toxin A for cricopharyngeal dystonia.
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Suppression of erythropoiesis by intrauterine transfusions in hemolytic disease of the newborn: use of erythropoietin to treat the late anemia.
Hemolytic disease of the fetus and newborn has three phases of anemia: in utero, in the first week of life, and in the weeks and months after birth. Intrauterine transfusions can ameliorate the severity of both fetal and early anemia, but late anemia and the need for transfusion remain significant problems. Bone marrow hypoplasia--probably a result of suppression of erythropoiesis from the intrauterine transfusions--was documented in the three patients tested in our study. Because erythropoietin (EPO) levels have been found to be low (i.e., normal) in these previously transfused patients despite the degree of anemia, we treated four affected infants with EPO, 200 microliters/kg subcutaneously three times a week, and noted reticulocytosis and increased hemoglobin values 2 to 4 weeks later. One patient again had reticulocytopenic anemia when the EPO therapy was stopped but responded to retreatment. Our study indicates that EPO treatment may be effective in the management of late anemia and could help to decrease the need for postnatal transfusions.
Corticosteroid responsive mitochondrial encephalomyopathy.
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The pump that gave too much: accidental overinfusion of prostacyclin.
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Is the pre-operative removal of dentures necessary?
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Obstructed ventilation: the blocked catheter mount.
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Amplified expression of tumor necrosis factor receptor in cells transfected with Epstein-Barr virus shuttle vector cDNA libraries.
As an approach to isolate the cell-surface receptor for tumor necrosis factor (TNF), we have developed transfectants of human B-lymphoblastoid cells (UC cells) that overexpress the TNF receptor. These transfectants were isolated from UC cells transfected with cDNA libraries of HeLa or NG108 cells constructed in the mammalian expression vector EBO-pcD. This vector contains the Epstein-Barr virus origin of replication (ori-P) plus the EBNA-1 gene conferring replication function to ori-P and, therefore, the ability to replicate autonomously within the transfected cell (Margolskee, R.F., Kavathas, P., and Berg, P. (1988) Mol. Cell. Biol. 8, 2837-2947). Cells overexpressing the TNF receptor were identified and separated by the binding of fluoresceinated TNF and flow cytometric selection. Scatchard analysis of 125I-TNF binding data revealed a single class of high affinity receptors with a dissociation constant (Kd) of 0.2 to 2 nM and a receptor density of about 150,000 per cell, an increase of approximately 150-fold over UC cells. Cross-linking of receptor-ligand with bis-sulfosuccinimidyl suberate followed by polyacrylamide gel electrophoresis gave estimates of 87 and 104 kDa for the size of the complex. Based on its ability to bind TNF, a 68-kDa receptor protein was identified in cell extracts enriched for the receptor by using immobilized wheat germ agglutinin and TNF affinity chromatography. The difference in the estimated size of the receptor and the receptor-ligand complexes demonstrates that TNF binds to the receptor as a monomer or a dimer. Analysis of cDNA sequences conferring receptor amplification in transfectants revealed that plasmid DNA was present at 30 or more copies per cell, most likely integrated into the genomic DNA or organized into high molecular weight catenanes, and autonomously replicating units could not be recovered. Therefore, while this vector was useful in generating stable receptor-amplified cells, it was not maintained as a recoverable episome.
Milk tester's dermatitis.
Hand dermatitis is a frequent problem among workers in milk testing laboratories. An epidemiologic study was conducted at the Pennsylvania Dairy Herd Improvement Association Milk Testing Laboratory, where more than 300,000 milk samples are examined monthly for protein, butterfat, and "somatic" cells. These samples are preserved with potassium dichromate for transport from the farm to the laboratory. A survey of the laboratory was conducted and workers were interviewed. Eight of 16 subjects reported a history of occupationally exacerbated hand dermatitis. Three of 16 subjects had positive patch test results to potassium dichromate. Two of 15 subjects who underwent patch testing to milk preserved with potassium dichromate had positive reactions. None reacted to milk alone, bronopol, or Kathon CG. Two workers are receiving workers' compensation because of severe allergic contact dermatitis of the hands to potassium dichromate. We conclude that milk testing laboratory workers are at substantial risk for acquiring allergic contact dermatitis from milk preserved with potassium dichromate.