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Biomedical subjects

N Lambert

Publications and source records attributed to N Lambert.

At least 37 records · Page 2Linked to original sources
PubMed1996

Human cytochrome P450's are pro-oxidants in iron/ascorbate-initiated microsomal lipid peroxidation.

We have examined the effect of human cytochrome P450's (1A1,1A2,3A4,2A6,2B6,2D6,2E1) on ascorbate/iron-induced lipid peroxidation. Using microsomes prepared from human lymphoblastic cells enriched in recombinant cytochrome P450 isoenzymes, we have shown that the degree of peroxidation is a function of the amount of P450 present rather than the presence of any specific isoenzyme. Incorporated P450 increased the amount of peroxidation products by up to 2.1-fold compared to the control microsomes with no P450. It is therefore concluded that cytochrome P450's play a significant role in ascorbate/iron peroxidation.

Ascorbic Acid↗
PubMed1996

Are whole extracts and purified glucosinolates from cruciferous vegetables antioxidants?

Fruits and vegetables contain several classes of compounds that can potentially contribute to antioxidant activity, including vitamins, simple and complex phenolics, sulphur-containing compounds and glucosinolates. The glucosinolates are found in high concentration in many cruciferous vegetables, and it is well established that their breakdown products induce endogenous antioxidant defences such as quinone reductase and glutathione S-transferase in cells and in vivo. Despite the anticarcinogenic effect of these compounds in animal models, the direct antioxidant properties of this class of compounds have not been systematically studied. We therefore examined the free radical-scavenging properties of representative extracts and of purified glucosinolates from cruciferous vegetables, by measuring their effect on ascorbate- or NADPH/iron-induced peroxidation of human liver microsomes, ascorbate/iron-induced peroxidation on phospholipid liposomes, iron chelation and hydroxyl radical scavenging using the deoxyribose assay, total antioxidant potential using ABTS (2,2'-azinobis(3-ethyl-benzothiazoline-6-sulphonate)) and the bleomycin assay. Most of the extracts from cruciferous vegetables exhibited some antioxidant properties, although extracts from cooked Brussels sprouts increased the rate of microsomal lipid peroxidation. The effects in these assays were dependent upon processing and species of crucifer, and the glucosinolate content appeared to play a minor role in these effects, since purified glucosinolates exhibited only weak antioxidant properties. The total antioxidant activities of extracts from cooked and autolysed Brussels sprouts were identical within experimental error. This is probably due to the content of phenolics which is unaltered by autolysis, despite the differences between these samples in other assays especially NADPH-iron-induced lipid peroxidation of human liver microsomes. The results demonstrate that glucosinolates are unlikely to account for the direct antioxidant effects of extracts from cruciferous vegetables.

Antioxidants↗
PubMed1996

[Transmission of infection in oral medicine. Evaluation of the risk of transmission in the office surgery].

The present study was designed to estimate the risk of transmission of infectious diseases by dental equipment in stomatology. The protocol was carried out on 30 patients. The three following samples were collected from each patient: (a) oral flora before any treatment, (b) aerosol produced by the hand-piece before internal decontamination, (c) aerosol produced by the hand-piece after internal decontamination. The results of this study indicate there was a risk of transmission of infectious diseases in 3 cases (10%) with dental equipment, even if there were no consequences for healthy individuals. We have to improve the security in stomatology, with internal and external decontamination after each patient.

Adult↗
PubMed1995

T-cell receptor variable region of the beta-chain gene use in peripheral blood and multiple synovial membranes during rheumatoid arthritis.

In order to look for a site-specific T-cell response in RA SM, PCR analyses using oligonucleotide primers specific for 24 TCRBV (V beta) families were performed to compare the respective usage of each TCRBV gene by T cells present in PB and SM of 13 patients with RA. In four patients, SM cells from two or three sites of inflammation were subjected to analysis. In one patient, synovial tissue was studied at two different phases of the disease, resulting in a total number of 19 samples of SM cells, which were compared with paired samples of PB cells. The results showed that whereas all 24 TCRBV gene families could be detected in both PB and SM cells, there was some skewing of increased or decreased usage frequencies of particular TCR V beta genes among SM cells. Three TCRBV families were often overexpressed in SM: V beta 3, V beta 17, and V beta 22. Moreover, V beta 4 was often decreased in SM (7 out of 13). This decrease was statistically significant in the RA population studied. SM from different joints of a given patient showed similar variations of T-cell repertoire compared to PB, even 6 months later in the course of the disease. These results demonstrate a biased TCRBV gene utilization in RA SM. This bias appears to be similar in different joints and at different times in the course of the disease. No correlation was found between the bias of TCR repertoire in SM and the HLA typing of these patients.

Adult↗
PubMed1995

Plasma proteins as biomarkers of the aging process.

This study was designed to characterize the rat serum proteins as biomarkers of the normal aging process. Crossed immunoelectrophoresis or electroimmunodiffusion quantitation of proteins was performed in rats aged 6, 12, 24, and 30 mo. Selection of healthy animals was based on confrontation of crossed immunoelectrophoresis patterns with those of experimentally inflamed young adults and with individual anatomopathological data. Convergence of inflammatory patterns and severe histological lesions was the exclusion criterion. Senescence-induced decrease was demonstrated for eight proteins [negative senescence reactants (SRs-)] and increase for six proteins [positive SRs (SRs+)]. Most SRs belonged to the class of proteins responsive to acute inflammation [acute phase reactants (APRs)]. One SR+, the thyroxine-binding globulin, a high-affinity thyroid hormone binder, emerged as a particularly reliable senescence biomarker, showing the highest aging-related variation (8-fold increase from 6 to 30 mo) and not belonging to the APR class. Chronic treatment with perindopril, an angiotensin I-converting enzyme inhibitor used in heart and renal disease therapy, significantly enhanced thyroxine-binding capacity, possibly by preventing age-related alterations of serum lipids. Serum protein patterns prove valuable both as indexes for selecting aging animals free from superimposed pathologies and as parameters of senescence-induced changes in protein biosynthesis.

Acute-Phase Proteins↗
PubMed1994

Detection of cytomegalovirus, Epstein-Barr virus and herpes virus-6 in patients with rheumatoid arthritis with or without Sjögren's syndrome.

The frequency of latent viral infection by cytomegalovirus (CMV), Epstein-Barr virus (EBV) and herpes virus-6 (HHV-6) was investigated in patients with RA with or without Sjögren's syndrome (SS) and in normal controls. Virus presence was determined by polymerase chain amplification of DNA isolated from peripheral blood mononuclear or polymorphonuclear cells and/or saliva-derived mononuclear/epithelial cells. Anti-viral antibodies and autoantibodies were also assayed. Patients with RA both with and without SS were found to have a significantly increased frequency of latent viral infection (two-fold higher, P = 0.035 for EBV and seven-fold higher, P = 0.018 for HHV-6) compared to normal controls but only in cells isolated from saliva. The increased frequency of virally infected cells from the saliva of patients with RA, regardless of the SS status, when compared to normal controls may reflect the ongoing inflammatory process, the impact of therapy and/or a less effective local immune responsiveness.

Aged↗
PubMed1992

A study of D52S hen lysozyme-GlcNAc oligosaccharide complexes by NMR spectroscopy and electrospray mass spectrometry.

The production of a mutant hen lysozyme is described in which Asp-52, one of the catalytically important residues, is replaced by Ser. The mutant enzyme has very low catalytic activity but NMR studies show that its structure is closely similar to that of the wild-type protein. NMR experiments also show that well defined complexes are formed with GlcNAc4 and GlcNAc6 bound in the active site of the mutant enzyme. These complexes have been examined using electrospray mass spectrometry (ESMS). The most intense peaks arise from the uncomplexed protein indicating that dissociation takes place in the mass spectrometer under the conditions used here. Peaks from minor species corresponding to complexes between the protein and the oligosaccharides are, however, also observed. The possibility that the latter arise from novel covalent enzyme-saccharide complexes is discussed.

Acetylglucosamine↗
PubMed1992

Postobstructive enteropathy in infants with transient enterostomy: its consequences on the upper small intestinal functions.

Repeated or prolonged organic obstruction of the small intestine in the neonatal period can lead to severe refeeding problems, despite a transient ostomy. These problems are thought to result from a postobstructive enteropathy (POE) of the apparently normal small intestine segment above the obstruction. Ten infants with a POE, characterized by limited oral caloric and carbohydrate intakes and increased ostomy effluent, were compared with 8 controls with an enterostomy and a normal postoperative refeeding pattern. There was no statistical difference in the histomorphometric appearance of the mucosa or its digestive or absorptive capacity (brush-border hydrolases, glucose transport) between the two groups. The effluent and duodenal floras of the two groups were similar. However, all POE patients showed significant abnormal peristalsis characterized by barium and carmin transit times. This suggests that repeated or prolonged obstruction in the neonatal period could lead to a POE, caused by chronic motricity abnormalities of the small intestine above the obstruction. Although this POE is more frequent after small bowel atresia, it may also occur with other conditions causing prenatal and postnatal intestinal obstruction.

Enterostomy↗
PubMed1991

Complexity of Pseudomonas aeruginosa infection in cystic fibrosis: combined results from esterase electrophoresis and rDNA restriction fragment length polymorphism analysis.

Esterase electrophoretic typing and restriction fragment length polymorphism of ribosomal DNA regions (ribotyping) were used to differentiate 102 Pseudomonas aeruginosa clinical isolates obtained from chronic lung infection in 23 patients with cystic fibrosis (CF) and two reference strains (including the type strain ATCC 10145). Twenty-five zymotypes were obtained with the former method and 16 ribotypes with the latter. Combination of the two typing systems led to the finding of 30 different types. Our data highlights the physiopathological complexity of P. aeruginosa infection in CF as, in six individual cases, several types were found among isolates from a given patient. On the other hand, two unique types were found in two and three patients respectively, raising the possibility of cross-infections.

Cystic Fibrosis↗
PubMed1990

An investigation of the dissociation and denaturation of legumin by salts using laser light scattering and circular dichroism spectroscopy.

The dissociation of legumin, a 12 S seed storage globulin from Pisum sativum, has been studied by laser light scattering and circular dichroism spectroscopy. Salts from the Hofmeister series, in particular sodium perchlorate, were used as dissociating agents. The Mr 360,000 hexameric protein was found to dissociate first to trimers and further to monomers and the number of amino acids involved in the trimer-trimer interaction estimated to be 23(+/-4). Native legumin appears to be more strongly bound together than some analogous seed storage globulins from other plant species such as Arachis hypogaea or Sesamum indicum and the dissociation process was accompanied by some changes in conformation.

Circular Dichroism↗
PubMed1990

Hen egg white lysozyme expressed in, and secreted from, Aspergillus niger is correctly processed and folded.

We transformed Aspergillus niger with the full length cDNA gene encoding hen egg-white lysozyme (HEWL) and its secretion signal sequence. Lysozyme levels up to 12 mg/l were secreted when expression was controlled by the A. awamori glucoamylase (GAM) promoter and 1 mg/l when controlled by the A. nidulans glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter. N-terminal sequence analysis of the recombinant protein indicated that the signal peptide was correctly processed by the A. niger secretory apparatus. The specific catalytic activity of the recombinant protein was identical to that of authentic hen lysozyme. The recombinant HEWL was examined by 2D 1H-NMR spectroscopy and shown to have a spectrum identical to that of authentic HEWL indicating that the protein was correctly folded.

Amino Acid Sequence↗
PubMed1989

Structure of the globular protein vicilin revealed by scanning tunnelling microscopy.

Scanning tunnelling microscopy (s.t.m.) has been used to study the structure of the non-crystalline globular protein vicilin. Molecules were deposited on amorphous carbon substrates and imaged both in air and in vacuo without additional sample preparation. Current-voltage plots of an individual protein molecule are also reported. The s.t.m. images are compared with conventional transmission electron micrographs and with a model of vicilin based on small-angle synchrotron X-ray scattering data.

Electric Conductivity↗
PubMed1989

[Current bacteriologic status and therapeutic results in acute otitis media in children aged over 3 months].

355 children, 3 months to 15 years old, presenting with acute otitis media, underwent a bacteriological study of otitis exsudate. From November 1985 to September 1987, 162 myringotomy and 149 acute otitis media spontaneously discharging were studied in Paris. From October 1981 to September 1987, 62 myringotomy and 46 spontaneously discharging acute otitis were studied in Valognes. There was none pathogenic bacterium in respectively 20 and 14% of the samples. Two or more pathogenic bacterium were isolated in 24 and 7% of the samples. In Paris as in Valognes, 3 pathogens were predominants: Haemophilus (17% were beta-lactamase producers), S. pneumoniae and Staphylococcus. There was only 5 and 3% Streptococcus pyogenes, 2% Branhamella catarrhalis in Paris, none in Valognes. Pseudomonas was present only in case of spontaneous otorrhea, even if recent. For the moment, the combination of amoxicillin with clavulanic acid is not our first treatment in case of acute otitis media in children. Actually we prescribe amoxicillin alone, 50 to 100 mg/kg/day. If the child is allergic to beta lactamin, we give him the combination of trimethoprime and sulfamethoxazole.

Acute Disease↗