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Biomedical subjects

M Pelletier

Publications and source records attributed to M Pelletier.

At least 37 records · Page 2Linked to original sources
PubMed1998

The phosphoenolpyruvate:mannose phosphotransferase system of Streptococcus salivarius. Functional and biochemical characterization of IIABL(Man) and IIABH(Man).

Previous studies have suggested that the phosphoenolpyruvate:mannose phosphotransferase system of Streptococcus salivarius consists of a nonphosphorylated enzyme II domain that functions in tandem with a separate enzymatic complex called III(Man). The III(Man) complex is believed to be composed of two protein dimers with molecular masses of approximately 72 kDa. Analysis of these proteins by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate has indicated that one dimer is composed of two 38.9-kDa subunits called IIIH(Man), and the other of two 35.2-kDa subunits called IIIL(Man). This study was undertaken to determine (1) the number and nature of the phosphorylated residue(s) on IIIH(Man) and IIIL(Man) and the phosphorylation sequence allowing the transfer of the phosphoryl group from HPr(His approximately P) to the mannose:PTS substrates; (2) whether IIIH(Man) and IIIL(Man) originate from two different genes or result from a posttranslational modification; and (3) whether these two proteins are involved in the phosphorylation of 2-deoxyglucose, a substrate of the phosphoenolpyruvate:mannose phosphotransferase system. We showed that both IIIH(Man) and IIIL(Man) were phosphorylated on two histidine residues. One phosphate bond was heat-labile (phosphorylation at the N1 position of the imidazole ring), while the second was heat-resistant (phosphorylation at the N3 position of the imidazole ring). The sequence of the first phosphorylation site was deduced by comparing the N-terminal amino acid sequence of both forms of III(Man) with IIA domains of the EII-mannose family. The sequences of both forms were identical over the 15 first amino acids, that is, MIGIIIASHGKFAEG. The sequence of the second phosphorylation site was determined for IIIL(Man) as IHGQVATNxTP. Hence, IIIH(Man) and IIIL(Man) are PTS proteins of the IIAB type and should be renamed IIABH(Man) and IIABL(Man). IIABH(Man) and IIABL(Man) had different peptide profiles after digestion with proteases, indicating that these two proteins are encoded by two different genes. In vitro PEP-dependent phosphorylation assays conducted with a spontaneous mutant devoid of both forms of IIAB(Man) suggested that the phosphoenolpyruvate:mannose phosphotransferase system of S. salivarius is composed of an uncharacterized nonphosphorylated membrane component that works in tandem with IIABL(Man). The physiological functions of IIABH(Man) remain unknown.

Amino Acid Sequence↗
PubMed1998

Successful treatment of acquired factor VIII inhibitors with cyclosporin.

The treatment of Factor VIII inhibitors remains controversial and no standard therapy exists. We describe in this report two consecutive patients with this inhibitor that responded to cyclosporin. Clinical improvement of the bleeding diathesis, a return to normal of the PTT, a decrease in the level of the inhibitor, and a return to normal of the factor VIII level followed use of this drug. We believe that cyclosporin is effective in the treatment of factor VIII inhibitors and deserves further investigation.

Adult↗
PubMed1998

Functional responses of human neutrophils to sodium sulfite (Na2SO3) in vitro.

An influx of neutrophils into the airways is a common feature observed during pulmonary inflammation induced by air pollutants, including sulfur dioxide and sulfates. In the present study focusing on the in vitro interactions of sodium sulfite (Na2SO3) with human neutrophils, we confirm results indicating that this sulfite induces superoxide production (O2-) by itself. We demonstrated that this response can occur more rapidly than previously reported (within 5 min), and that Na2SO3 can act as a priming agent, in a concentration-dependent fashion, to the bacterial tripeptide N-formyl-methionine-leucine-phenylalanine (fMLP) by increasing O2-production. In addition, our results show that Na2SO3 induces gene expression in human neutrophils in a concentration-dependent manner as assessed by incorporation of 5-[3H] uridine into total RNA. However, it does not induce cell shape changes. We also demonstrated that Na2SO3 does not modulate neutrophil apoptosis nor reverse the well-known delaying effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on apoptosis. We conclude that Na2SO3 acts rapidly on neutrophil physiology, within a few minutes with respect to superoxide production, and a few hours (4 h) with respect to gene expression without altering a biological process such as the rate of apoptosis evaluated after a long period of incubation (20 h). We further conclude that Na2SO3-induced production of O2does not drive neutrophils to undergo apoptosis, a mechanism known to occur in other conditions. Therefore, the potential toxicity of Na2SO3 during pulmonary inflammation or lung-associated diseases may be related to its ability to induce superoxide production without altering neutrophil apoptosis rate.

Apoptosis↗
PubMed1997

The phosphoenolpyruvate:sugar phosphotransferase system of oral streptococci and its role in the control of sugar metabolism.

Oral streptococci are sugar-fermentative bacteria comprising at least 19 distinct species and are a significant proportion of the normal microbial population of the mouth and upper respiratory tract of humans. These streptococci transport several sugars by the phosphoenolpyruvate:sugar phosphotransferase system (PTS) which concomitantly catalyzes the phosphorylation and translocation of mono- and disaccharides via a chain of enzymic reactions that transfer a phosphate group from phosphoenolpyruvate to the incoming sugar. A number of PTS components, including HPr, Enzyme I and some Enzymes II, have been studied at the biochemical and/or genetical level in Streptococcus salivarius, Streptococcus mutans and Streptococcus sobrinus. Moreover, compelling evidence indicates that the oral streptococcal PTS is involved in the regulation of sugar metabolism. Results are accumulating suggesting that a protein called IIABMan, as well as the phosphocarrier protein HPr, are key regulatory components that allow these bacteria to select rapidly metabolizable sugars, such as glucose or fructose, over less readily utilizable carbohydrates. Circumstantial evidence suggests that the molecular mechanisms by which oral streptococcal PTS exert their regulatory functions differ from mechanisms in other Gram-negative or Gram-positive bacteria.

Bacterial Proteins↗
PubMed1996

Structure of the human retinoic acid receptor beta 1 gene.

We report the isolation and characterization of genomic sequences coding for the 5' end of human retinoic acid receptor beta 1, a fetal RAR isoform which is also expressed in small cell lung cancers. Primer extension analysis revealed a principal transcription start site with a secondary site 23 bp further upstream in both SCLC and fetal tissues. The sequences isolated were CpG-rich between -60 and the 3' end of the first exon but there were no features like a TATA-box or an Inr element. In several important aspects, the human RAR beta 1 differs from its mouse counterpart. The 5'-UTR is 823 bp long and is encoded by four exons (vs two in the mouse giving a 477 bp UTR). The 5' end of the mouse cDNA has been mapped to a 67 bp CT repeat which is absent in our sequences. We were also unable to find evidence for a human isoform RAR beta 3 which is widely expressed in mouse tissues.

Animals↗
PubMed1996

Plantar fasciitis: sonographic evaluation.

PURPOSE: To evaluate the sonographic findings of plantar fasciitis. MATERIALS AND METHODS: Both feet of 15 patients who had a clinical diagnosis of plantar fasciitis were evaluated with ultrasound (US) by using a 7.0-MHz linear-array transducer. Heel pain was unilateral in 11 patients and bilateral in four. Sagittal sonograms were obtained, and the thickness of the plantar fascia was measured at its proximal end near its insertion into the calcaneus. Other observations included hypoechoic fascia, fiber rupture, perifascial fluid collections, and calcifications. Both feet of 15 healthy volunteers were also evaluated as a control group. RESULTS: Plantar fascia thickness was significantly increased in the heels in patients with plantar fasciitis (3.2-6.8 mm; mean, 5.2 mm +/- 1.13) compared with their asymptomatic heels (2.0-4.0 mm; mean, 2.9 mm +/- 0.70) (P < .0001) and compared with the heels of the patients in the control group (1.6-3.8 mm; mean, 2.6 mm +/- 0.48) (P < .0001). The proximal plantar fascia of 16 (84%) symptomatic heels were diffusely hypoechoic compared with none of the patients' asymptomatic heels and only one heel of a patient in the volunteer group. No fascia rupture, perifascial fluid collection, or calcifications were identified. CONCLUSION: Increased thickness of the fascia and hypoechoic fascia are sonographic findings of plantar fasciitis. US may be a valuable noninvasive technique for the diagnosis of plantar fasciitis.

Case-Control Studies↗
PubMed1995

Distribution of proteins similar to IIIManH and IIIManL of the Streptococcus salivarius phosphoenolpyruvate:mannose-glucose phosphotransferase system among oral and nonoral bacteria.

In Streptococcus salivarius, the phosphoenolpyruvate (PEP):mannose-glucose phosphotransferase system, which concomitantly transports and phosphorylates mannose, glucose, fructose, and 2-deoxyglucose, is composed of the general energy-coupling proteins EI and HPr, the specific membrane-bound IIIMan, and two forms of a protein called IIIMan, with molecular weights of 38,900 (IIIManH) and 35,200 (IIIManL), that are found in the cytoplasm as well as associated with the membrane. Several lines of evidence suggest that IIIManH and/or IIIManL are involved in the control of sugar metabolism. To determine whether other bacteria possess these proteins, we tested for their presence in 28 oral streptococcus strains, 3 nonoral streptococcus strains, 2 lactococcus strains, 2 enterococcus strains, 2 bacillus strains, 1 lactobacillus strain, Staphylococcus aureus, and Escherichia coli. Three approaches were used to determine whether the IIIMan proteins were present in these bacteria: (i) Western blot (immunoblot) analysis of cytoplasmic and membrane proteins, using anti-IIIManH and anti-IIIManH rabbit polyclonal antibodies; (ii) analysis of PEP-dependent phosphoproteins by polyacrylamide gel electrophoresis; and (iii) inhibition by anti-IIIMan antibodies of the PEP-dependent phosphorylation of 2-deoxyglucose (a mannose analog) by crude cellular extracts. Only the species S. salivarius and Streptococcus vestibularis possessed the two forms of IIIMan. Fifteen other streptococcal species possessed one protein with a molecular weight between 35,200 and 38,900 that cross-reacted with both antibodies. In the case of 9 species, a protein possessing the same electrophoretic mobility was phosphorylated at the expense of PEP. No such phosphoprotein, however, could be detected in the other six species. A III(Man)-like protein with a molecular weight of 35,500 was also detected in Lactobacillus casei by Western blot experiments as well as by PEP-dependent phosphoprotein analysis, and a protein with a molecular weight of 38,900 that cross-reacted with anti-III(Man) antibodies was detected in Lactococcus lactis. In several cases, the involvement of these putative III(Man) proteins in the PEP-dependent phosphorylation of 2-deoxyglucose was substantiated by the inhibition of phosphorylation activity of anti-III(Man) antibodies. No proteins cross-reacting with anti-III(Man) antibodies were detected in enterococci, bacilli, and E. coli. In S. aureus, a membrane protein with a molecular weight of 50,000 reacted strongly with the antibodies. This protein, however, was not phosphorylated at the expense of PEP.

Bacillus↗
PubMed1995

Acts and knowledge management in the NUCLEUS hospital information system.

NUCLEUS is a project completed in June 1995 in the frame of the European Community programme AIM (Advanced Informatics in Medicine). The main result of NUCLEUS is a prototype of an integrated patient dossier. Together with this patient dossier, facilities have been developed for its customisation by the various categories of end-users. A semantic model has been designed to guide and control the exploitation of data, and ensures the overall integrity of the information system.

Computer Communication Networks↗
PubMed1994

Fetal isoform of human retinoic acid receptor beta expressed in small cell lung cancer lines.

The retinoic acid receptor type beta (RAR beta) complementary DNA from a small cell tumor line was amplified, sequenced, and found to be homologous to the murine RAR beta 1. Seventeen lung tumor lines were analyzed. Five of seven small cell lung carcinoma lines expressed RAR beta 1, but only one other line (epidermoid) expressed the isoform, and this was at trace levels. Two other epidermoid lines, as well as three adenocarcinoma, two adenosquamous, and two large cell-derived lines did not express RAR beta 1. Nine adult human tissues, including lung, were analyzed, and in contrast to what has been reported for the mouse, undetectable or barely detectable levels were observed. On the other hand, a total of 13 different fetal tissues, at three different developmental stages, all expressed RAR beta 1. RAR beta 1 may be a master developmental gene in humans, and the remarkably specific association with small cell lung carcinoma suggests a molecular link between this type of cancer and development.

Amino Acid Sequence↗
PubMed1993

Emotions experienced and coping strategies used by family members of organ donors.

In this descriptive study guided by the Lazarus and Folkman (1984) stress and coping theory, donor family members' emotional responses and coping strategies used during the anticipation and confrontation stages of the organ donation experience were explored. Seven families from Eastern Canada who had lost a loved one suddenly and consented to organ donation were interviewed in their homes. The findings clearly showed that family members experienced a variety of emotions and used several different types of coping strategies. The findings of this study contribute to the development of knowledge required to guide nursing interventions to provide sensitive care to family members of organ donors.

Adaptation, Psychological↗
PubMed1992

The organ donor family members' perception of stressful situations during the organ donation experience.

The purpose of this study was to determine what the individual organ/tissue donor family members appraised as most stressful during the anticipation, confrontation and post-confrontation stages of the organ-donation process. The Lazarus and Folkman stress and coping theory guided the development and interpretation of the study. Family members who had lost a loved one suddenly and consented to donation in 1988 were interviewed. Data were analysed by means of content analysis. Findings showed that family members appraised different types of stressful situations during the three stages. The most frequently reported stressful situations centred around the threat of losing a loved one, confirmation of brain death, failure of the health professionals to identify the loved one as a potential donor and to approach the family regarding organ donation, and adjusting to the many changes associated with the loss. Significantly, five families requested donation, while two readily consented when approached. All family members reported that organ donation had helped with their grief. The findings of this study contribute to the development of knowledge required to guide nursing interventions to provide sensitive care to donors and their families.

Adaptation, Psychological↗
PubMed1991

IL-1 production by human thymic dendritic cells: studies on the interrelation with DC accessory function.

Thymic dendritic cells (DC) have been proposed to play a critical role in the generation of immunocompetent T lymphocytes. Since IL-1 is widely considered to be an important second signal in T cell stimulation, we have studied the ability of isolated human thymic DC to produce IL-1. Using the EL4/CTLL conversion assay standardized with recombinant IL-1 beta (rIL-1 beta), we demonstrate that upon LPS-stimulation thymic DC produce small amounts of IL-1 as compared to peripheral blood monocytes (PBM). In contrast with PBM, DC IL-1 production is not influenced by indomethacin. IL-1 activity was detected in the supernatants of DC cultures from all thymuses tested, although quantitative variability was noted among individual thymic donors. The specificity of the active factor was confirmed by neutralization assays with anti-IL-1 beta mAb. On the other hand, we demonstrate that rIL-1 beta cannot substitute for nor amplify the accessory function of thymic DC and that anti-IL-1 beta mAb fails to block the DC accessory function. Thus we conclude that IL-1 beta might not be a major factor for the efficient DC accessory function toward mature thymocytes recently demonstrated in our laboratory. Of interest, IL-1 beta was also detected in the supernatants of DC-thymocyte cocultures in the absence of mitogenic factor, suggesting that thymocyte contacts can constitute a sufficient signal to induce DC to produce IL-1. These observations indicate that human thymic DC represent an intrathymic source of IL-1 whose role in thymocyte proliferation or maturation remains to be understood.

Antigen-Presenting Cells↗