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Biomedical subjects

L Coulon

Publications and source records attributed to L Coulon.

15 recordsLinked to original sources
PubMed2001

The surface antigen SAG3 mediates the attachment of Toxoplasma gondii to cell-surface proteoglycans.

The attachment of Toxoplasma gondii to target cells is mediated by recognition of cellular heparan sulfate proteoglycans (HSPGs). The present study was performed to determine whether SAG1 and SAG3, two of the parasite surface antigens anchored to the membrane via glycosylphosphatidylinositol groups (GPIs), are involved in the tachyzoite binding to proteoglycans. The use of recombinant soluble forms of these proteins allowed us to demonstrate that SAG3, but not SAG1, interacts specifically with cellular HSPGs. Indeed, soluble recombinant SAG3 protein (recSAG3) was found to bind to immobilized heparin, whereas recSAG1 did not interact with this glycoaminoglycan. The specific adherence of recSAG3 to CHO cells was inhibited by soluble glycoconjugates, of which heparin, fucoidan and dextran sulfate were the most effective. Moreover, binding of recSAG3 to two HSPGs-deficient cell mutants was reduced by up to 80%. Proteoglycan sulfation was critical for SAG3 adherence to HSPGs as incubation of cells in the presence of sodium chlorate drastically reduced the recSAG3 binding. Finally, preincubation of CHO cells with recSAG3 blocked the adsorption of radiolabelled Toxoplasma tachyzoites. Taken together, these results indicate that SAG3 is a first glycoaminoglycan-binding protein associated with Toxoplasma, and SAG3-HSPGs interactions are involved in the parasite attachment to target cells.

Animals↗
PubMed2001

A profile of Little Athletes' injuries and the prevention methods used.

This study provides a profile of injuries sustained by Little Athletes and the injury prevention strategies they employed. The sample comprised 388 registered Little Athletes from seven Sydney New South Wales Clubs. Results from the survey and fieldwork suggested that at least one out of five Little Athletes had one or more injuries resulting from their participation in the current season. However, athletes aged under 11 to under 15 years were more likely to be injured than those in the younger age groups. The older athletes were also likely to have sustained more than four injuries during the season. Athletes reported low use of both warm up and warm down methods. Coaches, age managers and parents were portrayed as the key providers of information concerning injury prevention strategies. It was therefore noted that a valuable opportunity exists to create and design an innovative, age progressive educational package for Little Athletes, parents and coaches.

Adolescent↗
PubMed2001

12(S)-Hydroperoxy-eicosatetraenoic acid increases arachidonic acid availability in collagen-primed platelets.

Lipid hydroperoxides have been reported to regulate cell function and eicosanoid formation. The aim of the present study was to determine the effect of 12(S)-hydroperoxy-eicosatetraenoic acid [12(S)-HPETE], the platelet 12-lipoxygenase-derived hydroperoxide of arachidonic acid (AA), on the availability of nonesterified AA, which represents a rate-limiting step in the biosynthesis of eicosanoids. The coincubation of human platelets with concentrations of 12(S)-HPETE below 50 nM and subthreshold concentrations (STC) of collagen (less than 0.24 microg/ml) significantly enhanced platelet aggregation and the formation of thromboxane B(2), the stable catabolite of the potent aggregating agent thromboxane A(2). In addition, the nonesterified endogenous AA concentration increased by 3-fold. Arachidonoyl-containing molecular species concentrations of 1,2-diacyl-glycero-3-phosphocholine, 1-alkyl-2-acyl-glycero-3-phosphocholine, and 1-alkenyl-2-acyl-glycero-3-phosphoethanolamine decreased specifically in response to 12(S)-HPETE, whereas no significant changes were observed within 1,2-diacyl-glycero-3-phosphoethanolamine and 1,2-diacyl-glycero-3-phosphoinositol molecular species. The 12(S)-HPETE-induced increase in nonesterified AA was fully prevented by arachidonoyl trifluoromethyl ketone, an inhibitor of cytosolic phospholipase A(2) (cPLA(2)), and cPLA(2) was translocated to membranes and phosphorylated in platelets incubated with 12(S)-HPETE. In conclusion, these results indicate that nanomolar concentrations of 12(S)-HPETE could play a significant role in controlling the level of endogenous AA and the formation of thromboxane, thereby potentiating platelet function.

Arachidonic Acid↗
PubMed1996

The pursuit of excellence in nursing care: what does it mean?

This study explores the meaning of excellence in nursing care held by nurses. Qualitative data were collected from 156 undergraduate and postgraduate nurses by means of an open-ended questionnaire. Respondents were asked to reflect on practice which enabled a clear understanding of the meanings given to excellence in nursing care. In addition, details of their nursing background, level of nursing experience, and demographics were sought. Responses were content-analysed for themes by three coders. Four major themes emerged: (1) professionalism, (2) holistic care, (3) practice, (4) humanism. The fourth theme comprised three sub-themes: (a) enabling personal qualities, (b) nurse patient relationships, and (c) nurse-health team relationships. Responses revealed that professionalism constituted an all-encompassing theme subsuming all others. Findings suggested that the client is the central focus of excellent nursing care at all times. According to these respondents, nurses who deliver excellent nursing care implement nursing in a professional and competent manner, demonstrate a holistic approach to caring, possess certain personal qualities which enhance practice, and relate to patients, families, peers, hospital administrators and community members in a competent, cooperative manner. An important aspect of this study is the differential quality of responses provided by respondents, who were students enrolled in a nursing degree programme compared to respondents who were state-registered nurses and concurrently undertaking higher degree studies. The final result is suggestive of the stages of transition through which nurses pass in their quest for excellence.

Adolescent↗
PubMed1995

Implication of cytokines in the aggravation of malnutrition and hypercatabolism in elderly patients with severe pressure sores.

The objectives of this work were to study the production of the cytokines Interleukin 1 (IL-1), Interleukin 6 (IL-6), and tumour necrosis factor (TNF) in elderly patients with severe pressure sores and to assess their potential contribution to the aggravation of malnutrition. Nineteen bedridden patients with stage III or IV pressure sores, 12 bedridden patients free from pressure sores, but at risk of them, and 12 control patients without risk of pressure sores were studied. Nutritional status was evaluated using anthropometry, serum albumin, prealbumin, retinol-binding protein analyses, and delayed hypersensitivity skin tests. Acute-phase proteins (APP), cortisol, and cytokines blood levels together with cytokine production were measured. Nutritional status was poor in patients with sores and their APP, and IL-6 blood levels were significantly increased; IL-1 and TNF serum concentrations were not elevated in these patients. A significant difference in cortisol levels was observed between patients with stage III and IV sores. A local cytokine origin (especially IL-6, and also IL-1) was demonstrated. Thus cytokines, mainly IL-6, produced by tissue cells in damaged areas together with cortisol may aggravate malnutrition and hypercatabolism in patients with sores.

Acute-Phase Proteins↗
PubMed1992

Study of pentoxifylline induced modulation of TNF alpha and interleukin-6 secretion in healthy and septic patients by the use of an ex-vivo model on whole blood.

The aim of this work is to reinvestigate the pentoxifylline (PTX) action on TNF alpha and IL-6 production using a whole blood ex-vivo model. 5 healthy controls, 2 septic patients (4 samples) and 3 patients in septic shock (7 samples) have been studied. Our data confirm the inhibitory action of PTX on TNF alpha production in healthy controls. This inhibition is nearly complete for a PTX concentration of 10(-3) M. More surprisingly a suppressive activity of PTX on IL-6 secretion has been found both in controls and septic patients. On the 7 samples of the 3 patients with septic shock no TNF alpha production has been detected. Taken altogether, these observations suggest a potential role for PTX as a modulator of the major cytokines involved in the pathogenesis of septic shock.

Blood↗
PubMedDate not supplied

Cytokine production during intraperitoneal chemohyperthermia.

The aim of the present work is to investigate in vivo cytokine production during chemohyperthermia. 11 patients suffering from gastric adenocarcinoma (n = 6), ovarian adenocarcinoma (n = 4) or malignant mesothelioma (n = 1) were studied. Patients received 60 mg mitomycin or 100 mg cisplatin per square meter during 2 h in 6 liters of a heating solution (temperature 42 degrees C, flow rate 200 ml/min in a closed circuit) after previous surgical resection. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured at 0, 30, 45, 60 and 90 min, both in the blood stream and in the heating solution circulating intraperitoneally. We observed a slight increase in plasma IL-6 occurring as soon as 30 min, a dramatic rise in IL-6 in the heating solution. TNF-alpha values were only slightly augmented. In addition, the importance of various factors in the induction of IL-6 and TNF-alpha production during chemohyperthermia (temperature, mitomycin C, cisplatin) were studied using a whole blood ex vivo model.

Adenocarcinoma↗
PubMedDate not supplied

Analytical performances of commercial ELISA-kits for IL-2, IL-6 and TNF-alpha. A WHO study.

The determination of cytokine levels in biological fluids by accurate and sensitive methods is an absolute need to be able to define the involvement of these mediators in various clinical situations. To test if this goal was achieved with ELISA kits, a comparative study was undertaken using various commercial kits (6 for IL-2, 8 for IL-6 and 9 for TNF-alpha). The major aims of the work were to critically analyze the analytical performances of the kits and to illustrate some of the pitfalls the users may face. Substantial differences were noted in terms of sensitivity and behaviour of commercial standards versus international reference preparations. These results clearly illustrate the urgent need for a real standardization of immunoassays for cytokine quantitation.

Enzyme-Linked Immunosorbent Assay↗
PubMedDate not supplied

IndoChinese women's breastfeeding practices following immigration to Sydney: a pilot study.

Traditionally, most IndoChinese women breastfeed their children for a prolonged period. Recent studies indicate that there is a reduction in the rate and duration of breastfeeding by IndoChinese women following immigration to Western countries. The purpose of this pilot study was to compare pre- and post-migration attitudes of 20 IndoChinese women towards infant feeding. Triangulated methodology was used for data collection and frequency distribution and measures of association were used to analyse the quantitative data. Content analysis identified patterns and themes in the qualitative results. Findings revealed that following migration to Australia the women experienced significant sociocultural problems. Recommendations include in-depth studies of ethnic groups and 'tailor-made' education to promote breastfeeding.

Adult↗