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Biomedical subjects

M Meurisse

Publications and source records attributed to M Meurisse.

At least 109 records · Page 6Linked to original sources
PubMed1995

Simple radioimmunological assay of anti-alpha-galactosyl antibody (anti-Gal): application to autoimmune thyroid diseases and thyroid-associated ophthalmopathy.

Two radioimmunological techniques for the measurement of anti-alpha-galactosyl (anti-Gal) antibodies were developed and we demonstrated that this antibody is present in the serum of most untreated patients with Graves' disease, thyroid-associated ophthalmopathy (TAO) and autoimmune thyroiditis. Thyrotropin-binding inhibiting immunoglobulins (TBII) and Thyroid Stimulating Antibodies (TSAb) are frequently found in serum of patients with Graves' disease but not with autoimmune thyroiditis. Although TBII and anti-Gal were found sometimes simultaneously in the same serum samples, we demonstrated that anti-Gal could be present in the absence of TBII and reciprocally.

Animals↗
PubMed1995

Diaspirin crosslinked hemoglobin (DCLHb): absence of increased free radical generation following administration in a rabbit model of renal ischemia and reperfusion.

In control rabbits, a renal ischemia of 60 min followed by 10 min of reperfusion resulted in an enhanced free radical production in cortical tissue, as assessed by a significant decrease of free glutathione (42%), protein-bound GSH (17%), and vitamin E (49%). In contrast, catalase or glutathione peroxidase activities were not affected by these experimental conditions. Free radical production in this model was also measured directly using electron spin resonance (ESR) spectroscopy associated with a PBN (alpha-phenyl N-tert-butyl-nitrone) spin trap agent in the venous blood arising from the ischemic kidney. The signal consisted of a triplet of doublets. In contrast, no signal could be detected in control blood samples taken prior to inducing ischemia. The burst of free radical production occurred in the early phase after restoration of flow in the kidneys rendered ischemic, as evidenced by a signal of weak intensity which generally appeared within the third minute after reperfusion and progressively increased to form a well-defined asymmetric signal following 10 min of reperfusion. The precise nature of free radicals trapped by the PBN agent remains, however, to be elucidated, but analysis of the coupling constants (aN = 14.5-15 G; a beta H = 2.5-3 G) and asymmetry of the central doublets suggests that the ESR signal may arise from a nitorxy-radical adduct resulting from the spin trapping by PBN of both oxygen- or carbon-centered radicals of lipid origin. As evidenced by both direct and indirect measurements, exchange of rabbit blood immediately after inducing renal ischemia with 30 ml/kg of Diaspirin Crosslinked Hemoglobin (7.5 g/dl in lactated electrolyte) or human serum albumin (7.5 g/dl in lactated electrolyte) did not exacerbate free radical production mediated by an ischemia reperfusion phenomenon, a typical situation found in a resuscitation setting.

Animals↗
PubMed1994

Specific stimulation of Graves' disease thyrocytes by the natural anti-Gal antibody from normal and autologous serum.

Anti-Gal is a natural Ab abundantly produced in humans. It interacts specifically with the carbohydrate epitope Gal alpha 1-3Gal beta 1-4GlcNAc-R (termed the alpha-galactosyl epitope). This epitope is expressed in large amounts on thyrocytes of nonprimate mammals, but not of humans. We have previously found that binding of anti-Gal to alpha-galactosyl epitopes on porcine thyrocytes results in stimulatory effects similar to those exerted by thyroid-stimulating hormone (thyrotropin). In the present study, we tested the hypothesis that anti-Gal may contribute to Graves' disease (GD) pathogenesis by stimulation of the thyrocytes of patients with this autoimmune disorder. Anti-Gal binding and stimulatory effects were assessed in primary thyrocyte cultures. Anti-Gal specifically bound to GD thyrocytes and induced an increase in cAMP synthesis, 125I uptake, and DNA synthesis in these cells. Furthermore, the stimulatory effects of autologous sera on GD thyrocytes were greatly reduced after specific depletion of anti-Gal from these sera. No binding and no stimulatory effects of anti-Gal were observed, however, with normal human thyrocytes and with thyrocytes from thyrotoxic patients who lack thyroid-stimulating Igs or thyrotropin binding inhibiting Igs. These in vitro stimulatory effects of anti-Gal on GD thyrocytes suggest that this natural Ab may contribute to the in vivo continuous stimulation of thyrocytes in GD patients. The possibility that anti-Gal may stimulate GD thyrocytes via interaction with aberrantly expressed alpha-galactosyl epitopes on the thyroid-stimulating hormone receptor is discussed.

Adult↗
PubMed1994

Preservation of cortical microcirculation after kidney ischemia-reperfusion: value of an iron chelator.

Treatment of suprarenal aneurysms and renal artery reconstructions are both responsible for normothermic ischemia of the kidney (during clamping) followed by reperfusion (declamping). During reflow through an organ undergoing ischemia the production of free radicals can be associated with cell injury and a no-reflow phenomenon characterized by perfusion defects after a period of transient hyperemia. The objectives of this study were to demonstrate the existence of this phenomenon in the kidney undergoing ischemia followed by reperfusion and to test the potential protection afforded by an iron chelator (desferrioxamine) since free radical reactions are catalyzed by iron. Adult New Zealand white rabbits were divided into the following three groups: group A, 15 minutes of ischemia plus 10 minutes of reperfusion; group B, 60 minutes of ischemia plus 10 minutes of reperfusion; and group C, 60 minutes of ischemia plus 10 minutes of reperfusion combined with infusion of desferrioxamine (50 mg/kg). Cortical microcirculation in the kidney was measured by laser Doppler flowmeter before ischemia and 1, 5, and 10 minutes after reperfusion. Vitamin E content was determined in the cortex of the left kidney after 10 minutes of reperfusion and compared with that of the right (control) kidney. After 1 minute of reperfusion the cortical microcirculatory flow was significantly increased in all three groups (reactive hyperemia). In groups A and C blood flow returned to preclamping values after 10 minutes of reperfusion; however, blood flow in group B remained significantly reduced (29.2% +/- 10.5%) after 5 minutes of reperfusion with a further reduction to 48.5% +/- 5.7% after 10 minutes. These findings were correlated with the dosage of vitamin E since the vitamin E content was greatly reduced by 46.7% +/- 7.8% in group B but did not change significantly in groups A and C. This study shows that 60 minutes of normothermic ischemia is followed by a significant reduction in cortical microcirculatory flow (no-reflow phenomenon). Infusion of an iron chelator (desferrioxamine), however, which decreases the intensity of lipid peroxidation induced by the free radicals, preserves the microcirculatory flow.

Animals↗
PubMed1994

Cytokines and organ transplantation. A review.

Cytokines regulate both aspecific inflammatory responses and specific immune responses. Inflammatory changes occur in the organ transplant as a result of tissue trauma and ischemia/reperfusion in the organ donor and at the time of transplant operation. There is a possibility that cytokines play a role in mediating theses changes. These aspecific inflammatory changes may not only affect graft function but also influence graft immunogenicity (enhanced MHC and adhesion molecule expression) and thus, vulnerability to rejection. Cytokines orchestrate the specific immune response elicited by organ transplantation. Relevance of cytokines to the rejection reaction is multifactorial in nature: 1) promotion of the proliferation an differentiation of specific alloreactive T and B cells clones and differentiation and activation of CTL and NK cells, 2) chemotactic effect and induction of the expression of adhesion molecules, 3) enhancement of MHC class I and II expression, and 4) direct cytotoxic effect on the target grafted cells. Therefore, modulation of cytokine activity either specifically (monoclonal antibody, soluble receptor, etc.) or aspecifically (cyclosporin, FK 506, Rapamycin, steroids, etc.) is essential in controlling graft rejection. Determination of circulating cytokines and cytokines measurement within the biological fluids produced by an organ transplant may help in the diagnosis of rejection episodes and other complications following organ transplantation.

Antibody Formation↗
PubMed1994

Direct evidence of free radical production after ischaemia and reperfusion and protective effect of desferrioxamine: ESR and vitamin E studies.

After surgical renal revascularisation, warm renal ischaemia due to renal artery cross-clamping contributes to postoperative renal dysfunction. After reperfusion, free radicals are thought to be a significant cause of injury. Nevertheless, indisputable proof of free radical production is scarce, partly because of their transient nature. In this study, electron paramagnetic resonance and vitamin E levels were used to demonstrate the free radical production after renal ischaemia and reperfusion. Rabbit kidneys were submitted either to 15 or 60 minutes of ischaemia followed by reperfusion. A spin trap agent (alpha-phenyl-N-tert-butyl nitrone (PBN), 20mg/ml, 1 ml/min) was infused during reperfusion directly into the left renal artery via an aortic catheter before declamping. Blood samples were selectively drawn from the left renal vein for ESR analysis (Varian spectrometer E109) of lipidic residues extracted from blood samples. The vitamin E content of the left renal cortex was determined by HPLC procedure. The right renal cortex was used as a control for the vitamin E values. In the venous effluent, ESR analysis revealed the formation of a spectrum consisting of a triplet of asymmetric doublets. This signal resulted from the spin trapping by PBN of a mixture of both oxygen- and carbon- centred lipidic radicals. The amplitude of the signal which is proportional to the amount of free radicals was significantly higher after 60 minutes ischaemia than after 15 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Variable regions of chromosome 11 loss in different pathological tissues of a patient with the multiple endocrine neoplasia type I syndrome.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited disorder characterized by nodular proliferation of the parathyroid glands and tumors of the anterior pituitary gland, the endocrine pancreas, and the neuroendocrine cell system of the gut. Loss of the putative tumor suppressor effect of the MEN1 gene is probably responsible for the development of MEN1-associated tumors. We report here a genetic study of a female MEN1 patient with the association of nodular hyperplasia of two parathyroid glands, an insulinoma, multiple duodenal gastrinomas, a prolactinoma, and a gastric carcinoid. We performed loss of heterozygosity (LOH) studies of chromosome 11 on all affected tissues except the insulinoma. Allelic losses of chromosome 11 were detected in several tumors, but the chromosomal regions of LOH were different, suggesting that different somatic mutational events are involved in the pathogenesis of these tumors. LOH of chromosome 11 was also detected in the prolactinoma of this patient, which indicates that the MEN1 gene has a tumor suppressor effect in the pituitary.

Calcium↗
PubMed1993

Flexible technique for multiple organ procurement in rats: a training and research tool in transplantation.

Multiple organ procurement techniques are increasingly popular in many transplant centers. This paper describes a technique for multiorgan unit(s) explantation in rats. The procedure involves in situ preliminary dissection, cold perfusion of the thoracic and abdominal organ units as separate procedures, explantation, and finally the ex situ isolation of various organ units as single and/or multiple organ combination units. The procedure is feasible, allows for flexibility in the separation of combination organ units, and is reproducible. The exercise is provided as a training and research tool for clinical and research transplant surgeons. The technique is also presented as an animal model for clinical organ sharing.

Animals↗
PubMed1993

Conjugative transfer and in vitro/in vivo stability of the broad-host-range IncP R751 plasmid in Brucella spp.

Escherichia coli strain K12 BM14, carrying plasmid R751 (51.4 kb; Tpr, Tra+, IncP), was used as donor in matings with reference strains of the six Brucella nomenspecies, not known so far to harbor naturally occurring plasmids. R751 was easily transferred to and between Brucella spp., at frequencies ranging between 10(-1) and 10(-4). All Brucella transconjugants stably maintained plasmid R751 both in vitro and in vivo in our experimental conditions. No genetic modification of the plasmid during and after the conjugal transfer process could be deduced from the comparative restriction analysis (BamHI, HindIII, and EcoRI) in each Brucella transconjugant and in the E. coli donor.

Brucella↗
PubMed1993

Misdiagnosed malignancy in transplanted organs.

The case reports of three patients who received cancer-bearing organs at this institution are presented. A fourth recipient, who was to be transplanted with a cancerous kidney, was spared this disastrous complication. The relevant data regarding the donors is also alluded to, with special reference to the type and site of the primary malignancy. Following these case reports, the implications of these issues, their possible prevention, and further management are discussed.

Adult↗
PubMed1993

Evidence for free radical formation during human kidney transplantation.

Fourteen patients undergoing kidney transplantation were studied for evidence of the production of free radicals as assessed by the measurement of vitamin E (an index of lipid peroxidation) and of myeloperoxidase (a marker of neutrophil activation) in the systemic blood. Early (2 min) and late revascularization (30 min) of the kidney were respectively associated with a significant decrease of 35.5 and 40% of the initial level of plasma vitamin E. This consumption paralleled to the decrease of the vitamin E/total lipids ratio, a better indicator of vitamin E status. Heparin administration preceding renal artery clamping resulted in a twofold significant increase of baseline plasma myeloperoxidase (MPO) level (523 +/- 214 ng/ml). At kidney reperfusion, MPO concentration rose again and reached a maximum value of 1,653 +/- 882 ng/ml, indicating the presence of considerable neutrophil activation. A return to the baseline value was observed after 30 min of reperfusion. A short discussion about the possible origin of this MPO increase is given. Taken together, these data strongly suggest that free radical production, leading to lipid peroxidation phenomena, can occur within the early phase of kidney revascularization. Preliminary data using electron spin resonance with the spin-trapping technique strengthen this hypothesis.

Adult↗
PubMed1993

Successful revascularization of an orthotopic liver transplant (OLT) with the recipient right gastroepiploic artery.

A technique for revascularizing the arterial supply to an orthotopic liver transplant (OLT) in a 55-year-old male afflicted with end-stage alcoholic liver cirrhosis with portal hypertension is reported. The presence of well-developed portosystemic collaterals and an unsuitable recipient common hepatic artery necessitated the dissection and liberation of the right gastroepiploic artery (RGEA) for its subsequent use as the recipient arterial source. Posttransplantation, save for an early biliary leak which was corrected promptly, the patient's evolution was uneventful. Two separate celiac angiographic series at 6 weeks and 20 months posttransplantation revealed an excellent flow through the recipient and donor arterial systems. Additionally, the RGEA demonstrated an adaptation in caliber when pre- and posttransplantation angiograms were compared. It was concluded that the RGEA is a suitable rescue option for revascularization of OLT's provided it satisfies elementary hemodynamic requirements.

Angiography↗
PubMed1993

In vivo free radical production after cross-clamping and reperfusion of the renal artery in the rabbit.

Postischaemic reperfusion injury is often attributed to the generation of oxygenated free radicals which may subsequently promote lipid peroxidation in cell membranes. Electron paramagnetic resonance spectroscopy in association with the spin trap molecule alpha-phenyl-N-tert-butyl-nitrone allowed direct confirmation of lipid free radical production after renal ischaemia-reperfusion in an in vivo rabbit model. A 60-min period of ischaemia followed by reperfusion caused free radical production twofold greater than after 15 min of ischaemia. Glutathione and alpha-tocopherol have been measured in renal tissue, as indirect markers of lipid peroxidation. After 15 min of ischaemia followed by 10 min of reperfusion, the mean(s.e.m.) glutathione content of the ischaemic kidney was slightly but significantly reduced by 11.9(2.5)% (P < 0.003). The content of alpha-tocopherol was unchanged. However, 10 min of reperfusion following 60 min of ischaemia led to significant decrease in mean(s.e.m.) content of both glutathione (30.4(3.7)%) (2.23(0.2) versus 3.14(0.18) mumol/g wet tissue, P < 0.001) and alpha-tocopherol (46.1(7.8)%) (0.57(0.10) versus 1.09(0.14) micrograms/g wet tissue, P < 0.001) when compared to the control kidney. Under these experimental conditions, desferrioxamine (15 mg/kg administered intravenously before inducing ischaemia), a drug known to limit free radical production, significantly limited the decrease of alpha-tocopherol to 20.8(6.4)% (0.83(0.08) versus 1.05(0.04) micrograms/g wet tissue, P < 0.05), but did not prevent glutathione consumption in the reperfused kidney.

Animals↗