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Biomedical subjects

B Raymond

Publications and source records attributed to B Raymond.

14 recordsLinked to original sources
PubMed2006

The compatibility of a nucleopolyhedrosis virus control with resistance management for Bacillus thuringiensis: co-infection and cross-resistance studies with the diamondback moth, Plutella xylostella.

The use of genetically modified crops expressing Bacillus thuringiensis (Bt) toxins can lead to the reduction in application of broad-spectrum pesticides and an increased opportunity for supplementary biological control. Bt microbial sprays are also used by organic growers or as part of integrated pest management programs that rely on the use of natural enemies. In both applications the evolution of resistance to Bt toxins is a potential problem. Natural enemies (pathogens or insects) acting in combination with toxins can accelerate or decelerate the evolution of resistance to Bt. In the present study we investigated whether the use of a nucleopolyhedrovirus (AcMNPV) could potentially affect the evolution of resistance to the Bt toxin Cry1Ac in Plutella xylostella. At low toxin doses there was evidence for antagonistic interactions between AcMNPV and Cry1Ac resistant and susceptible insects. However, this antagonism was much stronger and more widespread for susceptible larvae; interactions were generally not distinguishable from additive for resistant larvae. Selection for resistance to Cry1Ac in two populations of P. xylostella with differing resistance mechanisms did not produce any correlated changes in resistance to AcMNPV. Stronger antagonistic interactions between Bt and AcMNPV on susceptible rather than resistant larvae can decrease the relative fitness between Bt-resistant and susceptible larvae. These interactions and the lack of cross-resistance between virus and toxin suggest that the use of NPV is compatible with resistance management to Bt products.

Animals↗
PubMed2005

Eicosanoid-mediated proinflammatory activity of Pseudomonas aeruginosa ExoU.

As Pseudomonas aeruginosa ExoU possesses two functional blocks of homology to calcium-independent (iPLA(2)) and cytosolic phospholipase A(2) (cPLA(2)), we addressed the question whether it would exhibit a proinflammatory activity by enhancing the synthesis of eicosanoids by host organisms. Endothelial cells from the HMEC-1 line infected with the ExoU-producing PA103 strain exhibited a potent release of arachidonic acid (AA) that could be significantly inhibited by methyl arachidonyl fluorophosphonate (MAFP), a specific PLA(2) inhibitor, as well as significant amounts of the cyclooxygenase (COX)-derived prostaglandins PGE(2) and PGI(2). Cells infected with an isogenic mutant defective in ExoU synthesis did not differ from non-infected cells in the AA release and produced prostanoids in significantly lower concentrations. Infection by PA103 induced a marked inflammatory response in two different in vivo experimental models. Inoculation of the parental bacteria into mice footpads led to an early increase in the infected limb volume that could be significantly reduced by inhibitors of both COX and lipoxygenase (ibuprofen and NDGA respectively). In an experimental respiratory infection model, bronchoalveolar lavage (BAL) from mice instilled with 10(4) cfu of PA103 exhibited a marked influx of inflammatory cells and PGE(2) release that could be significantly reduced by indomethacin, a non-selective COX inhibitor. Our results suggest that ExoU may contribute to P. aeruginosa pathogenesis by inducing an eicosanoid-mediated inflammatory response of host organisms.

Animals↗
PubMed2002

Systematic comparison of different algorithms for apnoea detection based on electrocardiogram recordings.

Sleep apnoea is a common disorder that is usually diagnosed through expensive studies conducted in sleep laboratories. Sleep apnoea is accompanied by a characteristic cyclic variation in heart rate or other changes in the waveform of the electrocardiogram (ECG). If sleep apnoea could be diagnosed using only the ECG, it could be possible to diagnose sleep apnoea automatically and inexpensively from ECG recordings acquired in the patient's home. This study had two parts. The first was to assess the ability of an overnight ECG recording to distinguish between patients with and without apnoea. The second was to assess whether the ECG could detect apnoea during each minute of the recording. An expert, who used additional physiological signals, assessed each of the recordings for apnoea. Research groups were invited to access data via the world-wide web and submit algorithm results to an international challenge linked to a conference. A training set of 35 recordings was made available for algorithm development, and results from a test set of 35 different recordings were made available for independent scoring. Thirteen algorithms were compared. The best algorithms made use of frequency-domain features to estimate changes in heart rate and the effect of respiration on the ECG waveform. Four of these algorithms achieved perfect scores of 100% in the first part of the study, and two achieved an accuracy of over 90% in the second part of the study.

Algorithms↗
PubMed1997

Classification of heart rate variability in patients with mild hypertension.

The diagnostic performance of two pattern classification methods to detect hypertension was evaluated in a population of 29 mildly hypertensive and 20 normal subjects. The heart rate variability (HRV) signal of each subject was recorded during rest and isometric handgrip exercise. Feature vectors composed of up to 6 features from both the time and frequency domain representation of the HRV signal were constructed and applied to a Bayes' likelihood classifier and a voting k-nearest neighbours classifier. Each subject was classified as hypertensive or normal, and the classification compared to the clinical diagnosis for each subject. The diagnostic performance of each classifier/feature vector combination was evaluated using the leave-one-out method. The best performance of 90% correct classifications was achieved using a nearest neighbour classifier, a Euclidean distance metric and 3 features. The Bayes' classifier achieved a best performance of 84% correct classification. The work shows promise for the detection of the autonomic disturbance which precedes and accompanies the hypertensive state.

Analysis of Variance↗
PubMed1990

What women think and what men think women think: perceptions of abuse and kindness in dating relationships.

The purpose of this study was to investigate how college women and their boyfriends viewed their relationships in terms of both abuse and kindness. The women filled out the Psychology Abuse-Kindness Relationship Inventory for themselves and their boyfriends responded to the questionnaire as they thought their girlfriends would. Several intriguing findings resulted: (1) Men thought their girlfriends would respond more negatively about the relationship than the women actually did. (2) Certain aspects of the relationship resulted in more discrepancies between the men's and women's perceptions. (3) Women distinguished present from past relationships by describing the former as more positive and the latter as more negative; men made no such distinction. Alternative explanations were offered to account for these results including projection, denial, projective identification, lack of psychological separation within couples, men's emotional upbringing and deeply rooted feelings towards women.

Adult↗
PubMed1989

Psychological abuse among college women in dating relationships.

A questionnaire designed to measure psychological abuse and kindness was responded to by 90 college women involved in dating relationships. Analysis indicated that, while many relationships were low abuse/high kindness, a substantial number were characterized by high abuse/low kindness, high abuse/high kindness and low abuse/low kindness. An analysis of these different categories of dating relationships as well as explanations as to why young women should be in such negative relationships are included. The study also indicated significant differences between women's reports of feelings and behaviors. Finally, a comparison of past versus present relationships showed proportionately few significant differences in behaviors but many significant differences in feelings. The major finding, that some college women are in dating relationships characterized by psychological abuse, was explored, and comparisons to the literature on wife abuse and courtship violence were also included.

Adult↗
PubMed1977

Auxin-induced H Secretion in Helianthus and Its Implications.

We have examined the ability of Helianthus hypocotyl segments as well as segments from a variety of other species to elongate in response to H(+) and to secrete H(+) in response to auxin and fusicoccin. In all cases a positive response was obtained when the cuticular barrier was abraded with carborundum. Removal of the cuticular barrier by "peeling" prevented detection of both auxin-induced elongation and H(+) secretion. Fusicoccin-induced growth and acid secretion are not prevented by peeling. These results suggest considerable tissue selectivity with respect to auxin action but considerably less specificity with respect to fusicoccin. It seems likely that in many dicots auxin-enhanced proton secretion and elongation are controlled by the epidermis and/or closely associated cell layers. The data presented in this paper provide further support for the acid growth theory of auxin action.

Journal Article↗
PubMed1977

Emanuel Hospital.

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Facility Design and Construction↗