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Biomedical subjects

M Lejeune

Publications and source records attributed to M Lejeune.

At least 19 recordsLinked to original sources
PubMed2006

Prostaglandin E2 receptor distribution and function in the gastrointestinal tract.

Prostaglandin E2 (PGE2) is one of the most important biologically active prostanoids found throughout the gastrointestinal tract. Despite the fact that PGE2 regulates many physiological functions of the gut including mucosal protection, gastrointestinal secretion and motility, it is implicated in the pathophysiology of inflammatory bowel diseases (IBD) and colorectal neoplasia. The varied biological functions exerted by PGE2 are through the pharmacologically distinct, G-protein coupled plasma membrane receptors termed EP receptors. Disruptions of various prostanoid receptor genes have helped in unravelling the physiological functions of these receptors. To date, all four subtypes of EP receptors have been individually knocked out in mice and various phenotypes have been reported for each subtype. Similarly, in vitro and in vivo studies using EP receptor agonists and antagonists have helped in uncoupling the diverse functions of PGE2 signalling involving distinct EP receptors in the gut. In this review, we will summarize and conceptualize the salient features of EP receptor subtypes, their regional functions in the gut and how expressions of EP receptors are altered during disease states.

Animals↗
PubMed2005

CD26, adenosine deaminase, and adenosine receptors mediate costimulatory signals in the immunological synapse.

Adenosine deaminase (ADA), a protein whose deficit leads to severe combined immunodeficiency, binds to the cell surface by means of either CD26, A(1) adenosine receptors, or A(2B) adenosine receptors. The physiological role of these interactions is not well understood. Our results show that by a 3-fold reduction in the EC(50) for the antigen, ADA potentiated T cell proliferation in autologous cocultures with antigen-pulsed immature or mature dendritic cells. Costimulation was not due to the enzymatic activity but to the interaction of ADA-CD26 complexes in T cells with an ADA-anchoring protein in dendritic cells. From colocalization studies, it is deduced that ADA colocalizing with adenosine receptors on dendritic cells interact with CD26 expressed on lymphocytes. This costimulatory signal in the immunological synapse leads to a marked increase (3- to 34-fold) in the production of the T helper 1 and proimmflamatory cytokines IFN-gamma, TNF-alpha, and IL-6.

Adenosine Deaminase↗
PubMed2005

Tailoring surface properties of biomedical polymers by implantation of Ar and He ions.

Ion implantation at 25 and 100 keV has been used as a tool for the modification of the surface properties of two biomedical polymers. The modulation induced by the different energy dispersion mechanisms of Ar and He have allowed satisfactory modifications for both the activation of the surfaces of chemically functional polycaprolactone (PCL) and the stabilization of anti-fouling poly(ethylene glycol) (PEG). In both cases the implantations have been performed at doses of 10(14) cm(-2) by taking into account the effect of different current densities, which are shown to distinctly influence the fragmentation-crosslinking of the target polymers. The resultant films were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, time of flight secondary ion mass spectroscopy and atomic force microscopy. Both shifts in zeta potential versus pH curves and the alteration of the polar components of the surface free energy (contact angle measurements) were correlated with the composition analysis. The response of the modified surfaces towards biomolecular interaction is demonstrated by the induction of preferential adsorption on irradiated PCL and the inhibited adsorption onto implanted PEG regions for selected oligopeptides and proteins.

Adsorption↗
PubMed2004

[Range of motion of the scoliotic spine in adults].

OBJECTIVE: To describe the movement of the trunk in adults with untreated adolescent idiopathic scoliosis (AIS) and to evaluate their relationship with the age of the patients, the location and angle of the curve, and the number of involved intervertebral segments. MATERIALS AND METHODS: Two hundred adult subjects with untreated AIS, without associated signs, were analyzed with rachimetry. The flexion, extension, bending, and rotation of the trunk were determined for each patient. The results were compared with a different sample: healthy subjects without spinal disease/other groups with more severe scoliosis (treated). RESULTS: In the absence of discopathy, regardless of the angle, location of the curve, or age of the patient, adults with untreated AIS demonstrated a 24% increase in truncal flexion, and a 30% decrease in hip flexion. The other movements studied with rachimetry were comparable to normal subjects. Lesions of the intervertebral segments increased in number and severity with age. These lesions progressively limited the mobility of the spine, initially in extension; and then in bending and flexion. CONCLUSIONS: The measurement of the mobility of the spine and the pelvis is part of the systematic examination of patients with adult scoliosis. This information can be used to improve the patients' health and spinal function; independent of their age and degree of spinal deformity.

Adolescent↗
PubMed2001

Cigarette smoking and attention: processing speed or specific effects?

RATIONALE: It has been evidenced that nicotine acts on some dimensions of human attention. OBJECTIVE: This study was carried out to test whether the positive effects of nicotine usually observed on the posterior system are specific or should rather be explained in terms of an effect of nicotine on eye movement velocity. METHODS: Ten participants were submitted to four tasks assessing attention. The tasks were borrowed from Zimmermann and Fimm's Battery for the Assessment of Attention: alert, eye movements, visual search and incompatibility. The order of the different tasks was balanced among participants. A within-subjects repeated-measure design was used. Participants received a 0.9-mg or 0.1-mg nicotine cigarette. The 0.1-mg cigarette was used as control. The order of administration of doses over sessions was counterbalanced. During the testing day, volunteers smoked their own cigarette and then waited 3 h without smoking. At the end of this abstinence period, participants completed the baseline tests before smoking an experimental cigarette ad libitum. They were then tested again. RESULTS: Participants who received nicotine appeared to respond faster in an eye movement task--a task associated with a non-elaborated attentional process. Similarly, their alert state improved. On the contrary, no effect of nicotine was observed in the incompatibility task and in the visual search task depending on elaborated attentional process. CONCLUSIONS: Data support previous observations and suggest that, first, non-elaborated information processing appeared to be more sensitive to nicotine and, second, this effect is not due to a velocity factor.

Adult↗
PubMed1999

Ferritin-associated iron induces neutrophil dysfunction in hemosiderosis.

Neutrophils (PMNs) from patients with secondary iron overload have an increased iron and ferritin content as well as a phagocytosis defect. Several serum components might be incriminated in the cellular iron accumulation. We therefore compared the effects on the PMN phagocytosis of total serum as well as the ferritin and transferrin fractions of serum derived from patients with thalassemia major and healthy control subjects. An incubation system of PMNs was developed. PMN phagocytosis was measured before and after incubation. Total serum from patients with thalassemia induced a defect that was prevented by co-incubation with deferoxamine (DFO). Gel-filtration chromatography was performed to separate the serum fraction containing transferrin and albumin from that containing ferritin. The transferrin-albumin fraction had no effect on PMN phagocytosis. On the contrary, the ferritin fraction of normal serum was deleterious to PMN phagocytosis, and the same fraction from thalassemic serum decreased PMN phagocytosis even more. Co-incubation with DFO or catalase improved this defect. Moreover, a cellular increase in the L-type subunit of ferritin was observed after the incubation of PMNs with the ferritin-containing fraction from thalassemic serum. In conclusion, serum from patients with thalassemia is toxic to PMNs, and this toxicity is due to ferritin-associated iron.

Adolescent↗
PubMed1999

Defective functional activity and accelerated apoptosis in neutrophils from children with cancer are differentially corrected by granulocyte and granulocyte-macrophage colony stimulating factors in vitro.

We have previously shown that polymorphonuclear leucocytes (PMN) harvested from children with cancer and exposed to chemotherapy exhibit defective bactericidal activities against both Gram-positive and Gram-negative microorganisms as well as accelerated apoptosis. In this study, PMN from children with cancer were evaluated to compare in vitro the corrective effects of the two myeloid colony stimulating factors G-CSF and GM-CSF on these defective pathways. Both G-CSF and GM-CSF were able to increase the defective bactericidal activities against S. aureus and E. coli. However, GM-CSF was consistently superior to G-CSF in correcting PMN microbicidal activity; this correction was incomplete since it did not reach the level observed in normal PMN exposed to GM-CSF. The accelerated apoptosis of PMN was not affected by G-CSF. In contrast, GM-CSF significantly prolonged the survival of the PMN although it did not reach the level of survival observed with normal PMN exposed to GM-CSF. These observations were consistent with other studies indicating that in PMN, microbicidal activities and apoptosis are differentially sensitive to the myeloid growth factors G-CSF and GM-CSF.

Adolescent↗
PubMed1998

Prolonged but reversible neutrophil dysfunctions differentially sensitive to granulocyte colony-stimulating factor in children with acute lymphoblastic leukaemia.

Treatment of average-risk acute lymphoblastic leukaemia (ALL) in children consists of 6 months of intensive chemotherapy followed by 18 months of maintenance therapy. Polymorphonuclear leucocyte (PMN) functions from children with ALL were studied in order to evaluate and compare the toxicity of the initial intensive treatment with the toxicity of the subsequent less intensive maintenance treatment. H2O2 and O2- production, evaluated by chemiluminescence, were significantly decreased during the intensive period but returned to normal values when maintenance therapy began. In contrast, bactericidal activity against Gram-positive and Gram-negative microorganisms remained at low levels throughout the treatment but returned to normal values in patients off chemotherapy. PMN from patients on maintenance therapy exhibited an excess of morphological changes associated with apoptosis. This was confirmed by standard two-colour flow cytometry which revealed an increase in the number of hypodiploid cells, and increased expression of membrane phosphatidylserine together with a drastic reduction in the expression of the Fcgamma receptor IIIB (CD16). These defective PMN were differentially sensitive to the effects of granulocyte colony stimulating factor (G-CSF): G-CSF induced similar increase in chemiluminescence in control and patient PMN; GSF partially corrected the defective bactericidal activity; G-CSF did not affect the accelerated PMN apoptosis. These observations indicate that ALL children undergoing chemotherapy present PMN defective functions which are partially sensitive or even resistant to G-CSF.

Adolescent↗
PubMed1996

Defective polymorphonuclear leukocyte functions in children receiving chemotherapy for cancer are partially restored by recombinant human granulocyte colony-stimulating factor in vitro.

Granulocyte colony-stimulating factor (G-CSF) has important direct and priming effects on different functions of normal mature polymorphonuclear leukocytes (PMNL). Previous study has shown an alteration in respiratory burst and bactericidal activities of PMNL harvested from children with cancer treated with chemotherapy. The present study evaluates the possibility that recombinant human (rh) G-CSF could correct these defective functions in vitro. Free radical formation in defective PMNL was enhanced by rhG-CSF to a level similar to that found in normal PMNL primed by rhG-CSF. The defective bactericidal activity against Escherichia coli and Staphylococcus aureus was also corrected. This bactericidal activity was not different from that observed in normal PMNL primed by rhG-CSF. In conclusion, correction of the altered free radical-formation pathway by rhG-CSF in these cells contributed to the restoration of normal bactericidal activity against both gram-positive and gram-negative microorganisms.

Adolescent↗
PubMed1996

Case study of quality assurance in the administration of chemotherapy.

The purpose of the study was to monitor the quality of chemotherapy administration within the department of oncology, of the university hospitals in Leuven (Belgium), by focusing on prescription and documented administration of chemotherapy. First, the actors and phases of the process were identified. Then selected patient records of three different types of chemotherapy were retrospectively analysed for 453 chemotherapy administrations. Study results indicated an important need to standardize the nursing and medical guidelines concerning chemotherapy administration. A formal task force was established to work on a multidisciplinary basis. The goals were to improve the routine process by identifying practical problems at any level and to standardize procedures by replacing all poorly defined "habits" by well-structured guidelines.

Antineoplastic Agents↗
PubMed1996

Granulocyte functions in children with cancer are differentially sensitive to the toxic effect of chemotherapy.

To analyze the toxicity associated to chemotherapy upon granulocytes, different functional assays were performed, within days of drug exposure and at time of bone marrow recovery, on polymorphonuclear neutrophils (PMN) from children with cancer. There were no significant postchemotherapy changes in the expression of the different receptors studied nor in the phagocytosis of Staphylococcus aureus 42D. By contrast, a significant decrease was observed in H2O2 production in PMN recently exposed to chemotherapy with both cytofluorometric and chemiluminescence assays. There was also a decrease in the production of O2- and in chemotaxis; finally, the intracellular killing of S. aureus 42D and Escherichia coli was reduced. In patients having recovered from drug-induced bone marrow aplasia, PMN functions were found to be normal except for bactericidal activity which was still defective. The observations indicate that, in patients exposed to chemotherapy, some PMN functions are transiently altered, whereas microorganism cell killing is continuously impaired.

Adolescent↗
PubMed1994

Role of nurses in cancer chemotherapy administration. Retrospective record analysis to improve role performance.

The purpose of this quality assurance project in the University Hospitals in Leuven, Belgium, was to describe, analyse and improve the actual routine practice of chemotherapy administration. The article focuses on analysis and improvement of role performance of nurses. The process of chemotherapy was systematically assessed by means of a retrospective analysis of patient records. This was done for 61 patient records receiving 453 chemotherapy administrations. Five aspects of the role of oncology nurses were described and analysed: data collection for prescription of chemotherapy, communication of instructions, preparation of the cytotoxic treatment, administration of cytotoxics and post-chemotherapy assessment. Data analysis showed variability in relation to several role aspects. Standardization of procedures and information was introduced to improve role performance in several areas.

Antineoplastic Agents↗
PubMed1994

Mental rehearsal in table tennis performance.

Effects of mental rehearsal were assessed on two measures of table tennis performance, counterattack forehand and counterattack backhand. Mental rehearsal combined with observational and physical techniques (N = 40) appeared to improve table tennis performance both qualitatively and quantitatively. Correlations suggested mental training effects cannot be explained only in terms of visual imagery.

Adult↗
PubMed1989

[An epidemiologic survey of caries frequency and periodontal status in children 6 to 15 years of age in 11 provincial regions in central France, Bourgogne and the Ile de France].

An epidemiological survey of dental caries and periodontal conditions was conducted on 2,022 children in eleven french "departments" of Center of France and part of Bourgogne and lle de France. It showed a dft of 3.03 and dfs of 4.83 at the age of 6 years, as well as an increasing DMFT from 0.65 at the age of 6 to 7.26 at the age of 15. The DMFS increased from 0.91 at 6 years to 12.31 at the age of 15. The calculus index increased steadily from 0.14 at the age of 6 to 0.64 at the age of 15. The gingival index increased from 0.27 in the 6 year old, to 0.55 in the 15 year old.

Adolescent↗
PubMed1981

Continuous subcutaneous insulin infusion in the treatment of juvenile-onset diabetes.

Control of glycemia by means of continuous subcutaneous insulin infusion (CSII) was examined in two groups of diabetic patients. In the first group of five totally insulin-dependent diabetics, the glycemic profile was compared in hospital during optimized conventional insulin therapy and CSII. A second group of five recently diagnosed diabetic patients was treated for periods up to 70 days with CSII. Two insulin infusion systems were used: (1) a commercially available infusion pump and (2) a specially developed device, permitting a more flexible infusion rate and including an audible warning of malfunction. In the first group the mean plasma glucose levels decreased significantly under CSII (202 +/- 18 mg/dl vs 151 +/- 18 mg/dl; p less than 0.05; mean +/- SEM) although the M value and the MAGE index were similar during CSII and the optimized conventional therapy. In the second group of subjects, improved diabetic control, as assessed by the mean blood glucose level (135 +/- 18 mg/dl), and M value and the MAGE index, was rapidly achieved by CSII in all patients. Insulin requirements fell to zero in two of the three patients who maintained CSII at home for 60 and 70 days. It is concluded that CSII permits blood glucose control at least as good as optimized conventional treatment in totally insulin-dependent diabetics in hospital as well as in newly diagnosed diabetics.

Adult↗