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Biomedical subjects

E E Benson

Publications and source records attributed to E E Benson.

12 recordsLinked to original sources
PubMed2001

Inhibition of hydrophobic protein-mediated Candida albicans attachment to endothelial cells during physiologic shear flow.

Adhesion interactions during hematogenous dissemination of Candida albicans likely involve a complex array of host and fungal factors. Possible C. albicans factors include changes in cell surface hydrophobicity and exposed antigens that have been shown in static adhesion assays to influence attachment events. We used a novel in vitro shear analysis system to investigate host-pathogen interactions and the role of fungal cell surface hydrophobicity in adhesion events with human endothelial cells under simulated physiologic shear. Endothelial monolayers were grown in capillary tubes and tested with and without interleukin-1 beta activation in buffered medium containing human serum. Hydrophobic and hydrophilic stationary-phase C. albicans yeast cells were infused into the system under shear flow and found to adhere with widely varying efficiencies. The average number of adherent foci was determined from multiple fields, sampled via video microscopy, between 8 and 12 min after infusion. Hydrophobic C. albicans cells demonstrated significantly more heterotypic binding events (Candida-endothelial cell) and greater homotypic binding events (Candida-Candida) than hydrophilic yeast cells. Cytokine activation of the endothelium significantly increased binding by hydrophobic C. albicans compared to unactivated host cells. Preincubation of hydrophobic yeast cells with a monoclonal antibody against hydrophobic cell wall proteins significantly blocked adhesion interactions with the endothelial monolayers. Because the antibody also blocks C. albicans binding to laminin and fibronectin, results suggest that vascular adhesion events with endothelial cells and exposed extracellular matrix may be blocked during C. albicans dissemination. Future studies will address the protective efficacy of blocking or redirecting blood-borne fungal cells to favor host defense mechanisms.

Adaptation, Physiological↗
PubMed2000

Studies of free radical-mediated cryoinjury in the unicellular green alga Euglena gracilis using a non-destructive hydroxyl radical assay: a novel approach for developing protistan cryopreservation strategies.

The development of cryoconservation methods for the long-term storage of algal cultures is important for the ex situ preservation of biological diversity and the maintenance of genetic stability within this group of important organisms. However, as many unicellular algae are recalcitrant to cryogenic storage, this study aims to evaluate the role of oxidative stress in cryoinjury. A non-invasive, non-destructive assay method previously applied to animal cells has been developed to evaluate free radical mediated oxidative stress in Euglena gracilis exposed to different cryopreservation treatments. The procedure employs dimethyl sulphoxide as a probe for the hydroxyl radical. Adopting this approach it was possible to identify those components of the cryopreservation protocol which were the most damaging. These were identified as preparative centrifugation and sub-zero freezing treatments. Poststorage survival in E. gracilis was significantly (P < 0.05) enhanced when the chelating agent desferrioxamine was included in the recovery medium whilst methane production was significantly (P < 0.004) reduced, suggesting that the additive was capable of ameliorating oxidative stress. The potential of using novel, exogenous antioxidant treatments developed for medical applications and applying them to enhance cryopreservation tolerance in recalcitrant unicellular algae is discussed.

Animals↗
PubMed1997

Malondialdehyde and 4-hydroxy-2-nonenal in plant tissue cultures: LC-MS determination of 2,4-dinitrophenylhydrazone derivatives.

The cytologically active secondary lipid peroxidation products, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE) have been detected as their 2,4-dinitrophenylhydrazone (DNP) derivatives in plant tissue cultures using LC-MS. This paper reports, for the first time, the use of LC-MS methodology to definitively identify 4-hydroxy-2-nonenal in plants. Limits of detection for the two derivatives are approximately 5 pmol (1.2 x 10(-9) g; 1 microM) and 0.1 pmol (3 x 10(-11) g; 20 nM) respectively. Mass spectrometer response was linear in the range from 2-200 microM DNP-MDA and 0.02-10 microM DNP-HNE. This methodology has been used to assess the formation of aldehydic secondary lipid peroxidation products in dedifferentiated callus cultures of Daucus carota. The finding that profiles of MDA and HNE can be correlated with embryogenic competence is of considerable interest as oxidative status has already been implicated as a regulatory factor in animal development.

Aldehydes↗
PubMed1994

Oxidative stress in recalcitrant tissue cultures of grapevine.

Thiobarbituric acid reactive substances (TBARS), and fluorescent compounds with spectral characteristics typical of products associated with oxidative stress in senescent and aging plant and animal cells, were detected in tissue cultures of the recalcitrant grapevine Vitis vinifera L. cultivar, Sultanina. These compounds increased during the early stages of dedifferentiation (callogenesis) of nodal stem explants. Catalase activity was not detected in the original explant, but was induced during callogenic dedifferentiation. Conversely, superoxide dismutase activity was detectable in the original explant, but diminished during the first week of callus induction. Transfer to callus induction medium promoted a large increase in the sulfhydryl content of nodal tissues. TBARS and fluorescent products accumulated in Sultanina callus during long-term culture (over 6 months). The possibility that oxidative stress may contribute to culture recalcitrance in this vine is discussed.

Agriculture↗
PubMedDate not supplied

The use of microsatellite analysis in Solanum tuberosum l. in vitro plantlets derived from cryopreserved germplasm.

This study reports the application of the encapsulation/dehydration cryopreservation and microsatellite analysis to the conservation of Solanum tuberosum cultivars Brodick and Golden Wonder. Cryopreserved shoot-tips were capable of up to 40% shoot and plantlet regeneration in Brodick and >60 % for Golden Wonder. Microsatellite analysis was used with genomic DNA of Golden Wonder and Desiree to establish DNA sequence length polymorphisms. As the basis of stability assessments this technique was applied to: (i) individual, field-grown, plants of Golden Wonder; (ii) individual Golden Wonder plants derived from a single parental tuber progeny; (iii) plantlets derived from in vitro cultures of Golden Wonder and Brodick and (iv) Golden Wonder and Brodick plantlets derived from cryopreserved germplasm

Cryopreservation↗
PubMedDate not supplied

Profiling cryopreservation protocols for Ribes ciliatum using differential scanning calorimetry.

DSC analysis was performed at three points in the cryopreservation process on encapsulated-dehydrated meristems of Ribes ciliatum. Meristems were excised from shoots pre-treated with either sucrose or glucose, encapsulated in alginate beads, dehydrated in sucrose solutions, air dried, and plunged in liquid nitrogen. Thermal analysis revealed glass transitions during cooling of air-desiccated meristems, however, on rewarming a small endothermic event was detected suggesting glass destabilization can occur. Interestingly, this did not occur in alginate beads or meristems when these components were cooled and rewarmed separately. The possibility exists that thermal and moisture gradients may arise within the alginate bead/tissue complex and we propose that the heterogeneous composition of the meristems and the surrounding alginate may promote ice nucleation on rewarming. The significance of this regarding the stabilization of glasses formed in alginate beads and their encapsulated meristems is discussed. This study also reports an approach to Ribes cryopreservation in which the pregrowth of shoots in 0.75M sucrose for 1 week can be used as a substitute for cold acclimation.

Journal Article↗