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Biomedical subjects

C Dalmasso

Publications and source records attributed to C Dalmasso.

At least 19 recordsLinked to original sources
PubMed2006

Radiation damage induced by krypton ions in sintered alpha-Al2O3.

Alpha-alumina is a useful thermoluminescence (TL) dosemeter. The knowledge of its behaviour under irradiation is thus of primary importance. The purpose of this paper is to characterise the radiation damage produced by swift krypton ions using various experimental methods, namely TL, optical absorption, fluorescence and electron paramagnetic resonance (EPR). After ion irradiation, the TL intensity is shown to decrease, whereas the optical absorption rises in the whole studied wavelength range. These two phenomena seem to be related to one another. Furthermore, optical absorption measurements highlight the appearance of new absorption bands probably owing to oxygen vacancies. Induced defects are also observed in the EPR spectra of irradiated pellets. They are likely related to electronic holes trapped on oxygen ions. The concentration of these defects increases with ion fluence and fluorescence measurements indicate that some pre-existing defects such as F2(2+) centres follow the same trend up to approximately 4.1 x 10(13) ions cm(-2).

Aluminum Oxide↗
PubMed2005

Nitric oxide pathway after long-term cold storage and reperfusion in a heterotopic rat heart transplantation model.

Recent studies have suggested the involvement of the nitric oxide (NO) pathway in ischemia-reperfusion injury related to cardiac transplantation. Herein, we assessed the NO pathway by quantifying endothelial (e) and inducible (i) nitric oxide synthase (NOS) expression and total NOS activity in a rat heart transplant model during cold ischemia with Celsior cardioplegia and reperfusion. Experiments were performed using a modified Lewis-Lewis heterotopic abdominal heart transplantation with 3 or 6 hours of ischemia with or without 1 hour of blood reperfusion. NOS expression and activity were determined using Western blotting and colorimetric assays, respectively, on freeze-clamped hearts after ischemia without (n = 10) or with reflow (n = 12) compared with basal values. Hearts submitted to 3 hours of ischemia and 1 hour of reperfusion showed a postischemic rate pressure product of 5190 +/- 3047 mm Hg/min (reversible ischemia), but no contractility was observed after 6 hours of ischemia. eNOS protein levels were lower after 3 hours of ischemia compared with the basal value (P = .0005) and were further decreased after 6 hours of ischemia (P < .0001 versus basal value and P = .0018 versus 3 hours of ischemia). Reperfusion did not further decrease eNOS protein levels. iNOS protein was not detected in any condition. NOS activity was increased after 3 hours of ischemia versus basal value (P = .0065) but not after 6 hours of ischemia without any effect of reperfusion. We concluded that eNOS expression was altered during ischemia and the amplitude of the alteration depended on the duration of ischemia. Reversible ischemia was associated with increased NOS activity at the end of ischemia with no variation at reperfusion.

Animals↗
PubMed2004

Antioxidant status of neonates exposed in utero to tobacco smoke.

To investigate the influence of maternal smoke exposure on neonatal and maternal antioxidant status, 39 mothers who were active smokers, 14 mothers exposed to environmental tobacco smoke (ETS), 17 controls, and their newborns were included in a prospective, controlled study. Plasma total antioxidant capacity, measured as total radical-trapping antioxidant parameter (TRAP) and ferric reducing antioxidant power (FRAP), and concentrations of specific antioxidants were measured in cord and in maternal blood. A similar, significant increase in ceruloplasmin concentration was observed in neonates born to actively smoking mothers and in those born to ETS exposed mothers. Uric acid and TRAP concentrations were significantly increased in ETS-exposed newborns and their mothers, compared to newborns and mothers from the active smoking and no-exposure groups with a trend towards increased uric acid, TRAP and FRAP concentrations being observed in the active smokers group. Neonatal and maternal antioxidant concentrations correlated significantly, except for ceruloplasmin. Cord blood vitamin A, E and C concentrations were unaffected by smoke exposure. These results show that maternal active smoking as well as ETS exposure significantly affect neonatal and maternal antioxidant status.

Adult↗
PubMed2004

[Multiple comparison procedures: principles, limits. Applications to microarray phenotype-genotype analysis].

BACKGROUND: When analysing data which simultaneously implicate a large number of statistical tests, one of the main problems is to take into account the multiplicity of these tests. The huge amount of comparisons done in studies of which the aim is to detect, using microarray, genes whose transcriptional changes are related to a biological or clinical outcome leads to a renewed interest for the multiple comparisons problem. However, this problem concerns many other fields such as psychometry, epidemiology, genetics. RESULTS: First, we introduce the multiple comparison framework. Then, we present the main procedures based on a global error rate called the "Family Wise Error Rate" (FWER) and those based on a false discovery rate expectancy (the "False Discovery Rate" (FDR) and the "positive False Discovery Rate" (pFDR)). Next, we apply the different procedures on a real dataset from a breast carcinoma study. Finally, we discuss the main results and we present guidelines for the use of these procedures.

False Positive Reactions↗
PubMed1995

Influence of photoisomers in bilirubin determinations on Kodak Ektachem and Hitachi analysers in neonatal specimens study of the contribution of structural and configurational isomers.

We compared data obtained with the Kodak Ektachem and Hitachi 717 Analysers and HPLC from 83 neonates under phototherapy. Total bilirubin values determined with the Kodak and Hitachi are in good agreement, but we observed a large discrepancy in the results for conjugated (Kodak) and direct (Hitachi) bilirubin. HPLC revealed that all the samples contained configurational isomers, while only 7.7% and 30.8% contained conjugated bilirubin and structural isomers, respectively. We developed a device for the specific and quantitative production of configurational or structural isomers, by irradiation with blue or green light. In vitro, total bilirubin values are coherent for the routine analysers in the presence of configurational or structural isomers. With configurational isomers, unconjugated bilirubin (Kodak) is lower than total bilirubin (Kodak), and conjugated bilirubin (Kodak) is always equal to zero, so the apparatus gives a false positive response for delta bilirubin. In contrast, the direct bilirubin (Hitachi) is constant. Furthermore, in the presence of structural isomers, unconjugated bilirubin (Kodak) is unexpectedly higher than total bilirubin (Kodak), conjugated bilirubin (Kodak) is proportional to the quantity of these isomers, and direct bilirubin (Hitachi) is constant. The contribution of photoisomers in bilirubin measurements is discussed.

Bilirubin↗
PubMed1993

Abnormal bilirubin binding to human serum albumin in a patient with unusual myeloma immunoglobulin G.

The binding of bilirubin was analysed in the serum of a patient with unusual myeloma. This patient presented an acquired Von Willebrand's disease due to the presence of a ternary complex formed by one molecule of myeloma immunoglobulin G and two molecules of albumin (Harlé et al. La Presse Médicale 19, 1661-1664 (1990)). The binding characteristics of bilirubin--number of sites (n) and association constants (k)--were estimated in the serum of the proband, and compared with those of purified human serum albumin and pooled normal human serum. The data suggest that complex formation between albumin and immunoglobulin induces abnormal bilirubin binding in the patient's serum, which becomes apparent when the bilirubin/albumin ratio exceeds 1.3. This abnormal binding may be due to conformational changes of the albumin molecule in the complex. The greatly increased number of lower affinity binding sites for bilirubin is certainly due to the abnormally high concentration of myeloma immunoglobulin G in the serum of the patient.

Bilirubin↗
PubMed1992

Twenty-four-hour hypothermic preservation of rat liver with Euro-Collins and UW solutions. A comparative evaluation by 31P NMR spectroscopy, biochemical assays, and light microscopy.

A comparative study of 24 hr preservation at 4 degrees C of excised rat livers with Euro-Collins and hydroxyethyl starch-free University of Wisconsin (UWm) solutions has been conducted based on the assessment of (1) the cellular energy status determined by 31P NMR spectroscopy and (2) cellular injury estimated from the loss of purine compounds (inosine, hypoxanthine, xanthine, and uric acid) during cold ischemia and reperfusion measured by HPLC, the leakage of intracellular enzymes, and the modifications of parenchyma established by light microscopy. Recovery of nucleosides di- and triphosphate was greater in the UWm group (80 +/- 6% vs. 58 +/- 6%) while inorganic phosphate formation was comparatively reduced. During hypothermic storage, the UWm groups generated a higher amount of inosine and hypoxanthine (in relation to the presence of adenosine in the protective solution) while no xanthine or uric acid was detected due to the inhibitory effect of allopurinol. Conversely, large quantities of xanthine and uric acid were found in the reperfusate of the EC group, pinpointing the cytotoxic role of oxygen-derived free radicals in the generation of cellular damage, as also illustrated by a higher aspartate aminotransferase leakage in the EC group (devoid of allopurinol and glutathione. Light microscopy indicated no histological alterations in the UWm group and mild alterations in the EC group that showed ballooning of hepatocytes (no lactobionate and raffinose in EC) and an alternation of clarifications and eosinophilic condensations. This study clearly confirms and illustrates the overall superiority of UWm solution in liver transplant preservation.

Adenosine↗
PubMed1992

Loss of endoplasmic reticulum membrane integrity: an image analysis of the glucose-6-phosphatase system in human hepatocyte.

Histochemical and cytochemical methods induce a loss of endoplasmic reticulum (ER) membrane integrity in hepatocytes. In order to evaluate the degree of ER membrane integrity, glucose-6-phosphatase (G6P-A) was localized in light and electron microscopy using glucose-6-phosphate (G6P) and mannose-6-phosphate (M6P) as substrates. In case of ER membrane alteration, M6P diffuses inside the ER and is hydrolysed by a non-specific phosphohydrolase. G6P and M6P hydrolysis was quantified with image analysis methods. In light microscopy, the ratio of reaction of M6P hydrolysis/G6P hydrolysis gave 75% of non specific reaction. In electron microscopic study this ratio was about 30%. These results showed that enzyme localization methods in electron microscopy produced less ER membrane alteration than light microscopic methods.

Endoplasmic Reticulum↗
PubMed1990

Interaction of beta-lactam antibiotics on bilirubin-albumin complex: comparison by three methods, total bilirubin, unbound bilirubin and erythrocyte-bound bilirubin.

The effects of 'third-generation' cephalosporins and penicillin analogues on the concentrations of total unconjugated bilirubin, unbound bilirubin and erythrocyte-bound bilirubin were determined in blood samples. This study was performed, in vitro, at two bilirubin/albumin molar ratios and at various concentrations of antibiotics. The most effective displacers, considering the three methods, were antibiotics tightly bound to albumin: ceftriaxone and cefotetan. Cefoperazone, which is bound to albumin as tightly as these two antibiotics, caused no significant increase in unbound bilirubin but should be considered as a displacer drug on the basis of the variations of erythrocyte-bound bilirubin and total bilirubin. We suggest that drug interaction on bilirubin-albumin binding be investigated by several methods.

Anti-Bacterial Agents↗
PubMed1990

Image analysis for histochemical study of glucose-6-phosphatase inactivation by diethyl pyrocarbonate in normal human liver.

Glucose-6-phosphatase (G6Pase) is a multicomponent system that catalyzes G6P hydrolysis. To determine the specificity of the histochemical reaction of G6Pase, we investigated the inhibitory effect of diethyl pyrocarbonate (DEPC), a specific and very effective inhibitor of the phosphohydrolase component of the G6Pase system, in normal human liver. The inactivation of the histochemical enzymatic activity by DEPC was monitored by determining the mean brightness of the microscopic image and the histogram of light intensity distributions. The results obtained indicate that the histogram is more sensitive than the mean brightness to variations of enzymatic activities, and that the percent of pixels brighter than a convenient level is directly proportional to DEPC concentration. This study indicates that DEPC can be used as an efficient inhibitor of the histochemical reaction of G6Pase.

Diethyl Pyrocarbonate↗
PubMed1987

Bilirubin displacement by ceftriaxone in neonates: evaluation by determination of 'free' bilirubin and erythrocyte-bound bilirubin.

Determination of 'free' bilirubin, erythrocyte-bound bilirubin and unconjugated bilirubin was used to test the effects of ceftriaxone on the binding of bilirubin to albumin. This study, performed on blood samples from icteric neonates, showed that the addition of ceftriaxone produced an increase of free bilirubin and erythrocyte-bound bilirubin and a decrease of unconjugated bilirubin. Ceftriaxone displays a significant displacing effect at concentrations obtained during therapeutic use and should be used with caution in high-risk jaundiced infants.

Bilirubin↗
PubMed1986

Displacement effect of ceftriaxone on bilirubin bound to human serum albumin.

The effects of ceftriaxone, a 'third-generation' cephalosporin, on bilirubin-serum albumin complexes were investigated. This study was performed on human adult samples at various bilirubin-albumin ratios. Ceftriaxone caused a decrease of unconjugated bilirubin and simultaneously an increase of erythrocyte-bound bilirubin. These variations were proportionally more important for low concentrations of antibiotic, including therapeutic values. It was concluded that ceftriaxone competes with bilirubin and displaces it from albumin-binding sites.

Bilirubin↗
PubMed1982

Comparative antigenic structure of carbonic anhydrases CA I and CA II from human and mammalian origin.

1. Isolated carbonic anhydrases CA I and CA II from different species (man, ox, sheep, pig, dog and rat) have been analyzed by immunodiffusion techniques using rabbit specific CA I or CA II antisera. 2. Immunodiffusion shows the absence of cross-reactivity between CA I and CA II isoenzymes. 3. Common antigenic determinants (cross-reactivities) were evidenced between the CA I of the different species under study. 4. To the contrary, cross-reactivity between CA II of the species mentioned above, can clearly be demonstrated only between bovine and sheep CA II.

Animals↗
PubMed1979

[Radioimmunoassay of carbonic anhydrase I and II in rats. Application to the central nervous system during ontogeny].

A specific radioimmunoassay method for rat erythrocyte carbonic anhydrases I and II was developed using a double antibody system. Its sensitivity was in the nanogram range for each of the two isozymes. The method has been applied to the assay of cerebral carbonic anhydrase. Only CAII has been found in brain extracts of perfused rats. Accordingly, the assay of CAI in cerebral tissue can be used to quantify erythrocyte contamination on condition that the ratio CAII/CAI in blood had been worked out. The developmental change in the soluble and the Triton X-100 solubilized brain CAII from birth to adult is reported.

Aging↗
PubMed1976

[Primary structure of bovine erythrocyte carbonic anhydrase CI. I. Tryptic peptides].

Bovine erythrocyte carbonic anhydrase CI consists of 259 amino acid residues including 18 lysines and 9 arginines. Its primary structure has been first investigated by isolation and sequence determination of the tryptic units. Acidification of the tryptic hydrolysate leads to the precipitation of 40% of the peptidic material. All the acid soluble peptides were isolated from the supernatant by chromatography on Dowex 50 W-X2 and Dowex 1-X2 followed by purification of heterogeneous fractions. Two of the three acid insoluble peptides were obtained in a pure form from the whole tryptic hydrolysate by gel filtration on Sephadex G-50 and chromatography on DEAE-Sephadex in alkaline medium. The sequence of the so isolated tryptic units has been determined with the exception of two of them obtained in a very poor yield.

Amino Acid Sequence↗