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Biomedical subjects

D Olson

Publications and source records attributed to D Olson.

At least 19 recordsLinked to original sources
PubMed2004

A prospective controlled study of cognitive function during an amateur boxing tournament.

BACKGROUND: Few studies have reported acute postbout cognitive function in amateur boxers, and none have documented the effects of repeated boxing bouts within a short time frame. OBJECTIVE: To determine whether participation in a 7-day amateur boxing tournament is associated with acute deterioration in cognitive test performance. METHODS: A prospective study was done of 82 collegiate amateur boxers participating in a 7-day single elimination tournament and a group of 30 matched nonboxing control participants. No participants had a history of recent concussion or past history of brain injury. For boxers, cognitive assessment using a computerized test battery was performed before the tournament and within 2 hours of completing each bout. Tests of simple and choice reaction time, working memory, and learning were administered. Analysis of variance was conducted to compare the serial performance of control participants with that of boxers participating in one, two, and three bouts. RESULTS: The 82 boxers fought 159 times. Cognitive testing was performed after 142 of these bouts. On simple reaction time, choice reaction time, and working memory tasks, the serial performance of boxers participating in three bouts (n = 22) was equivalent to that of boxers participating in two bouts (n = 22) and one bout (n = 32) and to nonboxing control participants (n = 30). An improvement in performance was observed on the learning task in boxers participating in three bouts. Boxers whose bout was stopped by the referee (n = 7) displayed significant slowing in simple and choice reaction time. CONCLUSIONS: With the exception of boxers whose contest is stopped by the referee, amateur boxers participating in multiple bouts during a 7-day tournament display no evidence of cognitive dysfunction in the immediate postbout period.

Adult↗
PubMed2001

Purification and properties of Arabidopsis thaliana type 1 protein phosphatase (PP1).

The Arabidopsis thaliana type 1 protein phosphatase (PP1) catalytic subunit was released from its endogenous regulatory subunits by ethanol precipitation and purified by anion exchange and microcystin affinity chromatography. The enzyme was identified by MALDI-TOF mass spectrometry from a tryptic digest of the purified protein as a mixture of PP1 isoforms (TOPP 1-6) indicating that at least 4-6 of the eight known PP1 proteins are expressed in sufficient quantities for purification from A. thaliana suspension cells. The enzyme had a final specific activity of 8950 mU/mg using glycogen phosphorylase a as substrate, had a subunit molecular mass of 35 kDa as determined by SDS-PAGE and behaved as a monomeric protein of approx. 39 kDa on Superose 12 gel filtration chromatography. Similar to the mammalian type 1 protein phosphatases, the A. thaliana enzyme was potently inhibited by Inhibitor-2 (IC(50)=0.65 nM), tautomycin (IC(50)=0.06 nM), microcystin-LR (IC(50)=0.01 nM), nodularin (IC(50)=0.035 nM), calyculin A (IC(50)=0.09 nM), okadaic acid (IC(50)=20 nM) and cantharidin (IC(50)=60 nM). The enzyme was also inhibited by fostriecin (IC(50)=22 microM), NaF (IC(50)=2.1 mM), Pi (IC(50)=9.5 mM), and PPi (IC(50)=0.07 mM). Purification of the free catalytic subunit allowed it to be used to probe protein phosphatase holoenzyme complexes that were enriched on Q-Sepharose and a microcystin-Sepharose affinity matrix and confirmed several proteins to be PP1 targeting subunits.

Amino Acid Sequence↗
PubMed2001

Model-independent source imaging using two-pion correlations in (2 to 8)a GeV Au+Au collisions.

We report a particle source imaging analysis based on two-pion correlations in high multiplicity Au+Au collisions at beam energies between 2A and 8A GeV. We apply the imaging technique introduced by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. The extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional Hanburg-Brown-Twiss analysis.

Journal Article↗
PubMed2001

Conditional vascular cell adhesion molecule 1 deletion in mice: impaired lymphocyte migration to bone marrow.

We generated vascular cell adhesion molecule (VCAM)-1 "knock-in" mice and Cre recombinase transgenic mice to delete the VCAM-1 gene (vcam-1) in whole mice, thereby overcoming the embryonic lethality seen with conventional vcam-1-deficient mice. vcam-1 knock-in mice expressed normal levels of VCAM-1 but showed loss of VCAM-1 on endothelial and hematopoietic cells when interbred with a "TIE2Cre" transgene. Analysis of peripheral blood from conditional vcam-1-deficient mice revealed mild leukocytosis, including elevated immature B cell numbers. Conversely, the bone marrow (BM) had reduced immature B cell numbers, but normal numbers of pro-B cells. vcam-1-deficient mice also had reduced mature IgD+ B and T cells in BM and a greatly reduced capacity to support short-term migration of transferred B cells, CD4+ T cells, CD8+ T cells, and preactivated CD4+ T cells to the BM. Thus, we report an until now unappreciated dominant role for VCAM-1 in lymphocyte homing to BM.

Animals↗
PubMed2001

The importance of impermeant support in small bowel preservation: a morphologic, metabolic and functional study.

BACKGROUND: Ambiguity exists as to which preservation solution is the most effective for small bowel (SB); studies have shown equivalent results with normal saline and University of Wisconsin (UW) solution. This study was designed to investigate the requirement of SB for oncotic and osmotic support, thereby reassessing one of the key principles of static organ storage. METHODS: Rodent SB was vascularly flushed with the following solutions: group 1, 0.9% saline (154 mM NaCl); group 2, 154 mM NaCl +5% dextran; group 3, 104 mM NaCl +100 mM lactobionate + 5% dextran; and group 4, UW solution. Analysis of cellular energetics, permeability and histology (by electron microscopy) was performed over a 10-h time course of cold storage. RESULTS: The addition of dextran and lactobionate to a simple saline solution (group 3) resulted in superior maintenance of several key parameters of energy metabolism throughout prolonged storage. At all times, ATP/ADP and EC ratios in group 3 remained unchanged from those of freshly isolated tissue; storage in normal saline and UW solution resulted in a progressive decline between 1 and 10 h of storage. ATP was also notably greater in group 3 than in group 1 or UW after 10 h of storage. Functional parameters demonstrated significant improvements in maintaining barrier function and membrane ion/electrical activity in group 3. Of particular note, after 10 h of storage, permeability for groups 1, 3 and UW was 215, 76 and 400 nmol/cm2/h, respectively, compared with a fresh tissue value of 22 nmol/cm2/h. Scanning electron micrographs revealed complete epithelial denudation of bowel stored in simple saline and UW solutions at 10 h. The incorporation of 100 mM lactobionate plus 5% dextran in group 3 prevented extensive villus denudation; the presence of intact microvilli indicated normal epithelial cell morphology. CONCLUSION: The order of solution effectiveness was group 3 > group 2 > group 1 > group 4. Vascular supplied impermeants, when supplied in simple solution, provide markedly improved preservation of metabolism, barrier function, and morphology of SB compared with UW.

Adenosine↗
PubMed2001

Initial evidence of endothelial cell apoptosis as a mechanism of systemic capillary leak syndrome.

BACKGROUND: Systemic capillary leak syndrome (SCLS) is a rare disorder of unknown etiology that is characterized by acute recurrent attacks of hypovolemic shock commonly following an inflammatory stimulus such as a viral illness. Prophylactic therapy is generally ineffective, and the outcome is frequently fatal. METHODS: In order to investigate the cellular mechanisms leading to SCLS, we examined the effects of sera from two patients with active SCLS on microvascular endothelial cell apoptosis in vitro. Apoptosis was determined by morphologic criteria, DNA fragmentation, annexin V stain, and by a quantitative photometric assay. The apoptotic pathway was investigated by Western blot of endothelial cells lysate after exposure to SCLS sera. RESULTS: The sera from patients with active SCLS mediated profound apoptosis of microvascular endothelial cells shortly after exposure. The exposed microvascular endothelial cells underwent immediate apoptosis as evidenced by morphologic changes, plasma membrane phosphatidylserine exposure, and by DNA fragmentation. Increased Bax/Bcl-2 ratio in endothelial cells exposed to SCLS sera was observed and suggested an oxidation injury as the possible mechanism for endothelial apoptosis. This potential mechanism was further explored by measuring intracellular reactive oxygen species (ROS) following SCLS serum exposure. Sera from both patients caused marked increases in ROS, initially detectable at 1 h and persisted for at least 12 h, with control serum from healthy subjects showing no effect on basal endothelial cell ROS concentrations. CONCLUSION: Components from the sera of patients with active systemic capillary leak syndrome in contrast to healthy subject sera mediate early and extensive endothelial apoptosis in vitro that is associated with oxidation injury. These data represent compelling initial evidence for oxidation-induced apoptosis as a likely mechanism for endothelial injury leading to SCLS.

Apoptosis↗
PubMed2000

Extracellular calcium elicits a chemokinetic response from monocytes in vitro and in vivo.

Recruitment of macrophages to sites of cell death is critical for induction of an immunologic response. Calcium concentrations in extracellular fluids vary markedly, and are particularly high at sites of injury or infection. We hypothesized that extracellular calcium participates in modulating the immune response, perhaps acting via the seven-transmembrane calcium-sensing receptor (CaR) on mature monocytes/macrophages. We observed a dose-dependent increase in monocyte chemotaxis in response to extracellular calcium or the selective allosteric CaR activator NPS R-467. In contrast, monocytes derived from mice deficient in CaR lacked the normal chemotactic response to a calcium gradient. Notably, CaR activation of monocytes bearing the receptor synergistically augmented the transmigration response of monocytes to the chemokine MCP-1 in association with increased cell-surface expression of its cognate receptor, CCR2. Conversely, stimulation of monocytes with MCP-1 or SDF-1alpha reciprocally increased CaR expression, suggesting a dual-enhancing interaction of Ca(2+) with chemokines in recruiting inflammatory cells. Subcutaneous administration in mice of Ca(2+), MCP-1, or (more potently) the combination of Ca(2+) and MCP-1, elicited an inflammatory infiltrate consisting of monocytes/macrophages. Thus extracellular calcium functions as an ionic chemokinetic agent capable of modulating the innate immune response in vivo and in vitro by direct and indirect actions on monocytic cells. Calcium deposition may be both consequence and cause of chronic inflammatory changes at sites of injury, infection, and atherosclerosis.

Animals↗
PubMed2000

Gender differences in supported employment.

Questions about gender equity have been asked in many aspects of the disability field and have resulted in findings that women with disabilities have significantly different experiences than do men. We analyzed an existing database of information on supported employment and natural supports to ascertain whether gender plays an important role in the employment of people with mental retardation. The findings suggest that there are several important differences. Although women were perceived as being more socially appropriate on several dimensions, they worked in jobs traditionally stereotyped by gender. Women also typically worked fewer hours than did men and, therefore, earned less money, although not statistically significantly so. The pattern of findings suggests parallels with the broader society.

Adolescent↗
PubMed1999

From individuals to aggregations: the interplay between behavior and physics.

This paper analyses the processes by which organisms form groups and how social forces interact with environmental variability and transport. For aquatic organisms, the latter is especially important-will sheared or turbulent flows disrupt organism groups? To analyse such problems, we use individual-based models to study the environmental and social forces leading to grouping. The models are then embedded in turbulent flow fields to gain an understanding of the interplay between the forces acting on the individuals and the transport induced by the fluid motion. Instead of disruption of groups, we find that flows often enhance grouping by increasing the encounter rate among groups and thereby promoting merger into larger groups; the effect breaks down for strong flows. We discuss the transformation of individual-based models into continuum models for the density of organisms. A number of subtle difficulties arise in this process; however, we find that a direct comparison between the individual model and the continuum model is quite favorable. Finally, we examine the dynamics of group statistics and give an example of building an equation for the spatial and temporal variations of the group-size distribution from the individual-based simulations. These studies lay the groundwork for incorporating the effects of grouping into models of the large scale distributions of organisms as well as for examining the evolutionary consequences of group formation.

Animals↗
PubMed1999

Regulation of extracellular matrix proteins by transforming growth factor beta1 in cultured pulmonary endothelial cells.

Transforming growth factor beta-1 (TGF-beta1), which is present in lung tissue, has been suggested to play a role in modulating vascular cell function in vivo. The action of TGF-beta1 in vivo, especially at the local site of application to connective tissue, is anabolic and leads to pulmonary fibrosis and angiogenesis, strongly indicating that TGF-beta may have practical applications in repair of tissue injury caused by burns, trauma, or surgery. In the present study, we have used cultured bovine pulmonary artery endothelial (BPAE) cells as a model system. Expression of various proteins, including SPARC (secreted protein acidic and rich in cysteines), type IV procollagen and fibronectin (FN) was examined by radiolabeling the cells with [3H]proline, immunoprecipitation with specific antibodies, and Northern blot analyses by using specific cDNA probes. Cultured cells were labeled with [3H]proline for 24 h in either the absence or in the presence of TGF-beta1 (0-20 ng/ml). Incorporation of radioactivity was observed in a concentration-dependent manner, maximal at 5 ng/ml. Northern blot hybridization demonstrated that TGF-beta1 (5 ng/ml) treatment of BPAE cells caused an increase in steady-state levels

Animals↗
PubMed1999

Effects of mean airway pressure and tidal excursion on lung injury induced by mechanical ventilation in an isolated perfused rabbit lung model.

OBJECTIVE: To study the relative contributions of mean airway pressure (mPaw) and tidal excursion (V(T)) to ventilator-induced lung injury under constant perfusion conditions. DESIGN: Prospective, randomized study. SETTING: Experimental animal laboratory. SUBJECTS: Fifteen sets of isolated rabbit lungs. INTERVENTIONS: Rabbit lungs were perfused (constant flow, 500 mL/min; capillary pressure, 10 mm Hg) and randomized to be ventilated at identical peak transpulmonary pressure (pressure control ventilation [30 cm H2O and frequency of 20/min]) with three different ventilatory patterns that differed from each other by either mPaw or V(T): group A (low mPaw [13.4+/-0.2 cm H2O]/large V(T) [55+/-8 mL], n = 5); group B (high mPaw [21.2+/-0.2 cm H2O]/small V(T) [18+/-1 mL], n = 5); and group C (high mPaw [21.8+/-0.5 cm H2O]/large V(T) [53+/-5 mL], n = 5). MEASUREMENTS AND MAIN RESULTS: Continuous weight gain (edema formation), change in ultrafiltration coefficient (deltaKf, vascular permeability index), and histology (lung hemorrhage) were examined. In group A, deltaKf (0.08+/-0.08 g/min/cm H2O/100 g) was less than in group B (0.28+/-0.19 g/min/cm H2O/100 g) or group C (0.41+/-0.29 g/min/cm H2O/100 g) (p = .05). Group A experienced significantly less hemorrhage (histologic score, 5.4+/-2.2) than groups B (10.3+/-2.1) and C (11.1+/-3.0) (p < .05). A similar trend was observed for weight gain. In contrast to tidal excursion, mPaw was found to be a significant factor for lung hemorrhage and increased Kf (two-way analysis of variance; p < .05). Weight gain (r2 = .54, p = .04) and lung hemorrhage (r2 = .65, p = .01) correlated with the mean pulmonary artery pressure changes that resulted from the implementation of the ventilatory strategies. The difference between the changes in mPaw and mean pulmonary artery pressure linearly predicted deltaKf (p = .005 and .05, respectively, r2 = 0.73). CONCLUSIONS: Under these experimental conditions, mPaw contributes more than tidal excursion to lung hemorrhage and permeability alterations induced by mechanical ventilation.

Airway Resistance↗
PubMed1997

A humanized form of a CD4-specific monoclonal antibody exhibits decreased antigenicity and prolonged plasma half-life in rhesus monkeys while retaining its unique biological and antiviral properties.

Certain monoclonal antibodies (MAbs) directed against CD4 can efficiently block HIV-1 replication in vitro. To explore CD4-directed passive immunotherapy for prevention or treatment of AIDS virus infection, we previously examined the biological activity of a nondepleting CD4-specific murine MAb, mu5A8. This MAb, specific for domain 2 of CD4, blocks HIV-1 replication at a post-gp120-CD4 binding step. When administered to normal rhesus monkeys, all CD4+ target cells were coated with antibody, yet no cell clearance or measurable immunosuppression occurred. However, strong anti-mouse Ig responses rapidly developed in all monkeys. In the present study, we report a successfully humanized form of mu5A8 (hu5A8) that retains binding to both human and monkey CD4 and anti-AIDS virus activity. When administered intravenously to normal rhesus monkeys, hu5A8 bound to all target CD4+ cells without depletion and showed a significantly longer plasma half-life than mu5A8. Nevertheless, an anti-hu5A8 response directed predominantly against V region determinants did eventually appear within 2 to 4 weeks in most animals. However, when hu5A8 was administered to rhesus monkeys chronically infected with the simian immunodeficiency virus of macaques, anti-hu5A8 antibodies were not detected. Repeated administration of hu5A8 in these animals resulted in sustained plasma levels and CD4+ cell coating with humanized antibody for 6 weeks. These studies demonstrate the feasibility of chronic administration of CD4-specific MAb as a potential means of treating or preventing HIV-1 infection.

Amino Acid Sequence↗
PubMed1997

Recycling of the urokinase receptor upon internalization of the uPA:serpin complexes.

The GPI-anchored urokinase plasminogen activator receptor (uPAR) does not internalize free urokinase (uPA) but readily internalizes and degrades uPA:serpin complexes in a process that requires the alpha2-macroglobulin receptor/low density lipoprotein receptor-related protein (alpha2MR-LRP). This process is accompanied by the internalization of uPAR which renders it resistant to phosphatidylinositol-specific phospholipase C (PI-PLC). In this paper we show that during internalization of uPA:serpins at 37 degrees C, analysed by FACScan, immunofluorescence and immunoelectron microscopy, an initial decrease of cell surface uPAR was observed, followed by its reappearance at later times. This effect was not due to redistribution of previously intracellular receptors, nor to the surface expression of newly synthesized uPAR. Recycling was directly demonstrated in cell surface-biotinylated, uPA:PAI-1-exposed cells in which biotinylated uPAR was first internalized and subsequently recycled back to the surface upon incubation at 37 degrees C. In fact, uPAR was resistant to PI-PLC after the 4 degrees C binding of uPA:PAI-1 to biotinylated cells, but upon incubation at 37 degrees C PI-PLC-sensitive biotinylated uPAR reappeared at the cell surface. Binding of uPA:PAI-1 by uPAR, while essential to initiate the whole process, was, however, dispensable at later stages as both internalization and recycling of uPAR could be observed also after dissociation of the bound ligand from the cell surface.

Animals↗
PubMed1997

Case report: field-acquired subclinical Babesia equi infection confirmed by in vitro culture.

A horse with no prior clinical history of equine piroplasmosis tested negative for Babesia caballi and Babesia equi in the complement fixation test before importation into the United States from France. After 5 years in residence in the United States, the animal tested serologically positive for B. equi by the complement fixation test, the immunofluorescent antibody test, and Western blot analysis. The carrier status of the horse was confirmed by culture of B. equi parasites. In vitro culture offers an efficient and comparatively inexpensive method to determine the carrier status of horses suspected of harboring B. equi.

Animals↗
PubMed1996

What is training?

Explore the source record for details and available documents.

Journal Article↗
PubMed1996

Delirium and right-hemisphere dysfunction in cognitively impaired older persons.

Cognitive impairment has been repeatedly shown to be a delirium risk factor. Much indirect evidence suggests that right-hemisphere dysfunction plays a particularly important role. This retrospective, case-controlled study, from a 148-patient memory loss clinic database, compared neuropsychological measures of hemispheric function in cognitively impaired elderly veterans with and without a history of delirium. Eleven study subjects had a history compatible with DSM-III-R criteria for delirium. Controls selected from the same database had no known history of delirium and were matched for Mini-Mental State Examination scores and Geriatric Depression Scale scores. Compared to the controls, subjects with a history of delirium had significantly lower scores on Object Assembly and Visual Reproduction (p < .05), tests that are predominantly right-hemisphere dependent. There were no significant differences in left-hemisphere measures. It is concluded that right-hemisphere dysfunction may prove to be an important risk factor for delirium.

Aged↗
PubMed1996

Nonluteal estrous cycles of 3-week duration are initiated by anovulatory luteinizing hormone peaks in African elephants.

Previous attempts to characterize the estrous cycle of elephants have yielded conflicting estimates of cycle length and LH profiles. In order to establish artificial breeding programs in this species, resolution of these issues is needed. Therefore, four female African elephants housed at the Indianapolis Zoo were studied for approximately 6 mo beginning in December 1994. Blood was collected weekly, and the serum was immediately analyzed for progesterone (P4). Whenever the weekly concentration of P4 was found to be low, blood was collected one or four times per day. All serum samples were assayed for LH, and the daily samples were assayed for P4 and estradiol. Transient increases of serum LH (designated as peaks) were observed four times in each of the four females. Of these 16 LH peaks, 8 were classified as ovulatory LH (ovLH) peaks and 8 were classified as anovulatory LH (anLH) peaks. Peaks designated ovLH averaged 3.60 +/- 0.67 ng/ml (mean +/- SEM); serum P4 measured during these peaks began to increase 2-3 days before each ovLH peak and continued to increase for several weeks thereafter, reaching a peak of 675 +/- 35 pg/ml. The eight other LH peaks, designated anLH peaks, were of similar (p > 0.05) magnitude averaging 3.07 +/- 0.72 ng/ml, but the serum concentration of P4 remained very low (< 80 pg/ml) during and for several weeks after these peaks. Six peaks designated anLH occurred an average of 12.2 +/- 1.4 days after serum P4 had declined below 80 pg/ml. In each elephant, there was a regular sequence in which each ovLH peak was followed by a luteal-active period lasting about 60 days and then about 12 days later by one anLH peak. Each anLH peak was followed 19-22 days later by one ovLH peak, but serum P4 remained at nonluteal levels throughout this interval between peaks. The authors propose to designate this interval after the anLH peak and before the next ovLH peak as a nonluteal (i.e., low P4) estrous cycle of only 3-wk duration. Following each short nonluteal estrous cycle, there was a single ovLH peak that initiated one luteal-active estrous cycle lasting 10-11 wk until terminated by the next anLH peak. The present results demonstrate that nonpregnant African elephants, housed in the absence of males, alternate between short nonluteal estrous cycles and long luteal-active estrous cycles. Daily measurements of serum P4 can be used to distinguish between the two types of estrous cycles and thereby provide a clinical prediction about the optimum time for artificial insemination.

Animals↗