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Biomedical subjects

M Piot

Publications and source records attributed to M Piot.

18 recordsLinked to original sources
PubMed2005

Isolation and characterisation of a Lactobacillus helveticus ITG LH1 peptidase-rich sub-proteome.

Lactobacillus helveticus strains, one of the most nutritionally fastidious lactic acid bacteria, have a potent proteolytic system that makes them very interesting for different uses in the dairy industry. Its applications concern from cheese ripening to the preparation of fermented milk products with biologically active peptides. The cell-free extract (CFE) of Lactobacillus helveticus strain ITG LH1 was analysed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), using IPG immobiline dry strips (pH 4-7). With the aim to study the proteolytic enzymes expressed by Lactobacillus helveticus ITG LH1 grown in milk medium, a two step-chromatography methodology, based on ion exchange and affinity chromatography, was developed for the preparation of a peptidase-rich sub-proteome from the CFE of stationary growing cells. Several affinity chromatography columns were tested and among them a HiTrap Chelating column was selected as it provided the best performance for the enrichment in peptidases. Peptidase activities were studied using different beta-Naphtylamide (beta-NA) derivatives and specific activities were increased 50- to 100-fold by this chromatographic procedure. Sub-proteome characterisation was performed by 2D-PAGE, pH 4-7, followed by protein digestion with trypsin, analysis by MALDI-TOF mass spectrometry and subsequent database searches using peptide mass fingerprints. Among the most abundant proteins seven peptidases were present, namely the two general aminopeptidases (PepN, PepC), three dipeptidases (PepDA, PepV, PepQ) and two endopeptidases (PepO, PepO3), all of them corresponding to the catalytic classes of metallo- or cysteine-peptidases. Several stress proteins (such as heat shock proteins DnaK and GroEL) and other enzymes implied in bacterial metabolism, namely in the carbohydrate pathways (such as LDH), were also identified in the peptidase-rich sub-proteome.

Aminopeptidases↗
PubMed2003

Poor anticoagulant response to tissue factor pathway inhibitor in patients with venous thrombosis.

Tissue factor pathway inhibitor (TFPI) is of major importance in regulating the coagulation triggering effects of tissue factor. An association between TFPI deficiency and thrombosis has still not been clearly demonstrated. We evaluated the anticoagulant activity of exogenous TFPI added either to the plasma of patients with venous thrombosis (n = 118) or to the plasma of healthy controls similar in terms of mean age and sex ratio (n = 107). A poor anticoagulant response to TFPI, defined as TFPI resistance, was observed in 4.7% of controls and in 11.0% of patients. TFPI resistance was associated with an almost threefold increase in the risk of thrombosis and could therefore represent a novel hemostatic risk factor for venous thrombosis.

Adult↗
PubMed2001

Goats' milk of defective alpha(s1)-casein genotype decreases intestinal and systemic sensitization to beta-lactoglobulin in guinea pigs.

Contradictory results have been reported on the use of goats' milk in cows' milk allergy. In this study the hypothesis was tested, using a guinea pig model of cows' milk allergy, that these discrepancies could be due to the high genetic polymorphism of goats' milk proteins. Forty guinea pigs were fed over a 20 d period with pelleted diets containing one of the following: soyabean proteins (group S), cows' milk proteins (group CM), goats' milk proteins with high (group GM1) or low (group GM2) alpha(s1)-casein content. Parenteral sensitization to GM1 and GM2 proteins as also assessed. The sensitization was measured (1) by systemic IgG1 antibodies directed against bovine or caprine beta-lactoglobulin (beta-lg), alpha-lactalbumin (alpha-la) and whole caseins, and (2) by intestinal anaphylaxis measured in vitro in Ussing chambers, by the rise in short-circuit current (delta Isc) in response to milk proteins. Guinea pigs fed on CM and GM1 developed high titres (> 1500) of anti-beta-lg IgG1, with an important cross reactivity between goat and cow beta-lg. However, in guinea pigs fed on GM2, anti-goat beta-lg IgG1 antibodies were significantly decreased compared with GM1 guinea pigs (mean IgG1 titres were 546 and 2046 respectively), and the intestinal anaphylaxis was significantly decreased (3.5+/-4.5 microA/cm2) compared with that observed in GM1 guinea pigs (8.3+/-7.6 microA/cm2). Animals receiving GM1 or GM2 proteins via the parenteral route developed a marked sensitization. These results suggest that the discrepancies observed in the use of goats milk in cows' milk allergy could be due, at least in part, to the high genetic polymorphism of goats' milk proteins.

Anaphylaxis↗
PubMed2000

Hydrolysis of sequenced beta-casein peptides provides new insight into peptidase activity from thermophilic lactic acid bacteria and highlights intrinsic resistance of phosphopeptides.

The peptidases of thermophilic lactic acid bacteria have a key role in the proteolysis of Swiss cheeses during warm room ripening. To compare their peptidase activities toward a dairy substrate, a tryptic/chymotryptic hydrolysate of purified beta-casein was used. Thirty-four peptides from 3 to 35 amino acids, including three phosphorylated peptides, constitute the beta-casein hydrolysate, as shown by tandem mass spectrometry. Cell extracts prepared from Lactobacillus helveticus ITG LH1, ITG LH77, and CNRZ 32, Lactobacillus delbrueckii subsp. lactis ITG LL14 and ITG LL51, L. delbrueckii subsp. bulgaricus CNRZ 397 and NCDO 1489, and Streptococcus thermophilus CNRZ 385, CIP 102303, and TA 060 were standardized in protein. The peptidase activities were assessed with the beta-casein hydrolysate as the substrate at pH 5.5 and 24 degrees C (conditions of warm room ripening) by (i) free amino acid release, (ii) reverse-phase chromatography, and (iii) identification of undigested peptides by mass spectrometry. Regardless of strain, L. helveticus was the most efficient in hydrolyzing beta-casein peptides. Interestingly, cell extracts of S. thermophilus were not able to release a significant level of free proline from the beta-casein hydrolysate, which was consistent with the identification of numerous dipeptides containing proline. With the three lactic acid bacteria tested, the phosphorylated peptides remained undigested or weakly hydrolyzed indicating their high intrinsic resistance to peptidase activities. Finally, several sets of peptides differing by a single amino acid in a C-terminal position revealed the presence of at least one carboxypeptidase in the cell extracts of these species.

Amino Acid Sequence↗
PubMed1998

Prevalence of factor V Leiden (APCR) and other inherited thrombophilias in young patients with myocardial infarction and normal coronary arteries.

OBJECTIVE: To investigate the role of activated protein C resistance (APCR, factor V Leiden) in coronary artery thrombosis. METHODS: The prevalence of APCR and of congenital deficiencies of antithrombin III, protein C, protein S, plasminogen, and factor XII was investigated in adult patients under 45 years of age with acute myocardial infarction. The results were compared with those of a group of 53 age and sex matched control subjects. RESULTS: Among 75 patients under the age of 45 years who were admitted from November 1994 to April 1996 for acute myocardial infarction, 22 (29.3%) had normal coronary arteriography (group I) and 53 (70.7%) had significant coronary artery disease (group II). Inherited thrombophilia was more often found in group I (4/22, 18.2%) than in group II (4/53, 7.5%) but the difference was not significant (F test: p = 0.22). The prevalence of APCR was 9.1% (2/22) in group I, 3.8% (2/53) in group 2 (p = 0.57), and 3.8% (2/53) in the normal control group (p = 0.57). CONCLUSIONS: The prevalence of congenital thrombophilias, including APCR, does not seem to be increased in young patients with myocardial infarction and normal coronary angiograms, compared with young patients with coronary atherosclerosis and with normal control subjects. However, the statistical power of the study is too low to detect a significant difference and these results are published to allow a meta-analysis of this problem in the future.

Activated Protein C Resistance↗
PubMed1995

Isolation of hen egg white lysozyme, ovotransferrin and ovalbumin, using a quaternary ammonium bound to a highly crosslinked agarose matrix.

A single-step anion-exchange chromatographic separation of egg white proteins was carried out using a Q Sepharose Fast Flow column. The separation resulted in the isolation of two lysozyme peaks with purities of ca. 99 and 88%, one peak of ovotransferrin purified to ca. 75% and two ovalbumin peaks with purities of ca. 54 and 98%. Recoveries were estimated to be ca. 60, 100 and 83% for lysozyme, ovotransferrin and ovalbumin, respectively. The amino acid compositions of all collected peaks have also been determined. This confirmed the identity of some of the proteins contained in these peaks.

Animals↗
PubMed1995

Four adult patients with the missense mutation L206W and a mild cystic fibrosis phenotype.

We report molecular and clinical analyses in four unrelated patients with cystic fibrosis (CF) with compound heterozygosity for the L206W mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR). This uncommon missense mutation (frequency less than 1% in a sample of 336 CF chromosomes from Southern France) replaces a leucine by a tryptophan residue in the middle of the third transmembrane domain of CFTR. On the basis of the clinical features presented by the four patients, we postulate that the L206W might be associated with pancreatic sufficiency and residual transmembrane transport of chloride in lung.

Adolescent↗
PubMed1986

Newborn calf intestinal absorption of immunoglobulins extracted from colostrum.

In the newborn calf, colostrum immunoglobulin absorption was compared with absorption of immunoglobulins extracted from colostrum. Reduced absorption of the latter resulted in plasma immunoglobulin levels unable to protect the animals against infections. Adding complete milk powder to the immunoglobulin solution slightly improved the level of absorption. Postprandial plasma alkaline phosphatases levels exhibited changes differing with the nature of the meals. This reinforces the idea that intestinal function was probably disturbed by immunoglobulin solutions. Moreover, reduced appetite for immunoglobulin solution was evident by the second meal, when most of the animals previously subjected to this diet suffered from a variety of problems (scour, asthenia), possibly caused by harmful effects of immunoglobulin solution on their digestive tract.

Alkaline Phosphatase↗
PubMed1970

The use of jet-injectors in BCG vaccination.

In mass vaccination programmes, the jet-injection of vaccine may have considerable operational advantages over the classical techniques. The technical performance of two models of jet-injector, the Dermo-Jet and the Ped-O-Jet, in BCG vaccination was assessed in a number of studies which are reviewed by the authors. It is shown that the jet-injectors do not administer the full dose for which they are calibrated and that the size of the vaccination lesion varies more than after vaccination by syringe.By increasing the dosage considerably, the results of vaccination by jet-injection may be improved to a certain extent but the risk of unpleasant reactions is also increased.

BCG Vaccine↗
PubMedDate not supplied

[Severe bronchoalveolitis in chickenpox].

Varicella pneumonia, is commonly an easy diagnostic because of specific eruption. We report a case in an 8 years old child with moderately with-spread macular and purpuric rash. Hematologic data showed anemia and thrombocytopenia from central origin. Surgical biopsy of lung was performed with bacteriologic, parasitologic and virologic studies. The diagnostic was brought by ascension of serum complement fixation titers to varicella virus from 1/8 to 1/1024. This case is compared to those recorded in the literature.

Antibodies, Viral↗