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Biomedical subjects

P Rey

Publications and source records attributed to P Rey.

At least 37 records · Page 2Linked to original sources
PubMed2000

Involvement of CDSP 32, a drought-induced thioredoxin, in the response to oxidative stress in potato plants.

In animal cells, yeast and bacteria, thioredoxins are known to participate in the response to oxidative stress. We recently identified a novel type of plant thioredoxin named CDSP 32 for chloroplastic drought-induced stress protein of 32 kDa. In the present work, we measured comparable increases in the glutathione oxidation ratio and in the level of chlorophyll thermoluminescence, a specific marker for thylakoid lipid peroxidation in Solanum tuberosum plants subjected to drought or oxidative treatments (photooxidative stress, gamma irradiation and methyl viologen spraying). Further, substantial accumulations of CDSP 32 mRNA and protein were revealed upon oxidative treatments. These data show for the first time in plants the induction of a thioredoxin by oxidative stress. We conclude that CDSP 32 may preserve chloroplastic structures against oxidative injury upon drought.

Chlorophyll↗
PubMed2000

Over-expression of a pepper plastid lipid-associated protein in tobacco leads to changes in plastid ultrastructure and plant development upon stress.

Proteins homologous to fibrillin, a pepper plastid lipid-associated protein involved in carotenoid storage in fruit chromoplasts, have been recently identified in leaf chloroplasts from several species and shown to be induced upon environmental stress. To further investigate the role of the protein, transgenic Nicotiana tabacum plants over-expressing fibrillin using a constitutive promoter were generated. Transgenics grown under standard light intensities (300 micromol photons m-2 sec-1) were found to contain substantial amounts of fibrillin in flowers and leaves. In leaves, the protein was immunolocalized within chloroplasts in both stromal and thylakoid subfractions. No change was noticed in thylakoid structures from transgenics, but chloroplasts contained an increased number of plastoglobules organized in clusters. In petals, leucoplasts were also found to contain more agglutinated plastoglobules. The effects of environmental factors on fibrillin gene expression and protein localization were studied in tobacco leaves. Less fibrillin was present in plants grown under low light intensities, which can be explained by the involvement of a light-dependent splicing step in the control of fibrillin gene expression in leaves. Analysis of protein subfractions from plants subjected to drought or high light showed that both stresses resulted in fibrillin association with thylakoids. Whereas no growth difference between wild-type (WT) and transgenic plants was noticed under low light conditions, transgenics exhibit a longer main stem, enhanced development of lateral stems and accelerated floral development under higher light intensities. These data suggest that fibrillin-related proteins fulfil an important function in plant development in relation to environmental constraints.

Capsicum↗
PubMed2000

Oligandrin. A proteinaceous molecule produced by the mycoparasite Pythium oligandrum induces resistance to Phytophthora parasitica infection in tomato plants.

A low-molecular weight protein, termed oligandrin, was purified to homogeneity from the culture filtrate of the mycoparasitic fungus Pythium oligandrum. When applied to decapitated tomato (Lycopersicon esculentum Mill. var. Prisca) plants, this protein displayed the ability to induce plant defense reactions that contributed to restrict stem cell invasion by the pathogenic fungus Phytophthora parasitica. According to its N-terminal sequence, low-molecular weight, acidic isoelectric point, ultraviolet spectrum, and migration profile, the P. oligandrum-produced oligandrin was found to share some similarities with several elicitins from other Phytophthora spp. and Pythium spp. However, oligandrin did not induce hypersensitive reactions. A significant decrease in disease incidence was monitored in oligandrin-treated plants as compared with water-treated plants. Ultrastructural investigations of the infected tomato stem tissues from non-treated plants showed a rapid colonization of all tissues associated with a marked host cell disorganization. In stems from oligandrin-treated plants, restriction of fungal growth to the outermost tissues and decrease in pathogen viability were the main features of the host-pathogen interaction. Invading fungal cells were markedly damaged at a time when the cellulose component of their cell walls was quite well preserved. Host reactions included the plugging of intercellular spaces as well as the occasional formation of wall appositions at sites of potential pathogen entry. In addition, pathogen ingress in the epidermis was associated with the deposition of an electron-opaque material in most invaded intercellular spaces. This material, lining the primary walls, usually extended toward the inside to form deposits that frequently interacted with the wall of invading hyphae. In the absence of fungal challenge, host reactions were not detected.

Algal Proteins↗
PubMed1999

Cyclophosphamide and paclitaxel as initial or salvage regimen for the mobilization of peripheral blood progenitor cells.

Peripheral blood progenitor cells are now commonly used for hematologic reconstitution after myelosuppressive chemotherapy for hematologic and solid malignancies. The purpose of this study was to evaluate the activity of paclitaxel 170 mg/m2 and cyclophosphamide 2 g/m2 (CP) with filgrastim (human G-CSF) for mobilization of PBPCs as the first or second maneuver after failure with filgrastim alone. Sixty-four patients with stage II-IV breast cancer received (CP) followed by filgrastim (10 microg/kg/day). In 35 (55%) this was the first maneuver while it was for salvage in 29 (45%) patients. The median number of aphereses was two (range, 1-7). In 83% of the patients apheresis was initiated on days 10-11 following chemotherapy. The median numbers of CD34+ cells/kg, CD34+ cells/apheresis/kg and total nucleated cells/kg collected were 8.7 x 10(6) (2.11-73.5), 3.97 x 10(6) (0.3-36.75) and 164.15 x 10(8) (9-660), respectively. All the patients yielded at least 2 x 10(6) CD34+ cells/kg. CP mobilization salvaged the 29 patients who failed mobilization with filgrastim alone. When used as first-line mobilization the yield of CD34+ cells x 10(6)/kg was higher than in the salvage group (16.93 vs 3.94, P < 0.001). Patients receiving CP as salvage reached the target of 5 x 10(6) CD34+ cells/kg in only 45% (13/29) of cases vs 94.3% as first maneuver. CP followed by filgrastim is a safe and effective regimen for the mobilization of PBPCs in patients with breast cancer and shows significant activity in patients who failed to mobilize with filgrastim, suggesting a higher mobilization potential.

Adult↗
PubMed1998

A novel thioredoxin-like protein located in the chloroplast is induced by water deficit in Solanum tuberosum L. plants.

By analysing two-dimensional patterns of chloroplastic proteins from Solanum tuberosum, the authors observed the accumulation of a 32-kDa polypeptide in the stroma of plants subjected to water deficit. N-terminus and internal peptides of the protein, named CDSP 32 for chloroplastic drought-induced stress protein, showed no obvious homology with known sequences. Using a serum raised against the protein N-terminus, a cDNA encoding CDSP 32 was cloned by screening an expression library. The deduced mature CDSP 32 protein is 243 amino acids long and displays typical features of thioredoxins in the C-terminal region (122 residues). In particular, CDSP 32 contains a CGPC motif corresponding to a thioredoxin active site and a number of amino acids conferring thioredoxin-type structure. The CDSP 32 C-terminal region was expressed as a fusion protein in Escherichia coli and was shown to possess thioredoxin activity based on reduction assay of insulin disulfide bridges. RNA blot analysis showed that CDSP 32 transcript does not accumulate upon mild water deficit conditions corresponding to leaf relative water contents (RWC) around 85%, but high levels of CDSP 32 transcripts were observed for more severe stress conditions (RWC around 70%). In vivo labelling and immunoprecipitation revealed a substantial increase in CDSP 32 synthesis upon similar stress conditions. Rewatering of wilted plants caused decreases in both transcript and protein abundances. In tomato wild-type plants and ABA-deficient mutants, a similar accumulation of a CDSP 32-related transcript was observed upon water deficit, most likely indicating no requirement for ABA in the regulation of CDSP 32 synthesis. Based on these results, it is proposed that CDSP 32 plays a role in preservation of the thiol: disulfide redox potential of chloroplastic proteins during water deficit.

Amino Acid Sequence↗
PubMed1998

Molecular characterization of CDSP 34, a chloroplastic protein induced by water deficit in Solanum tuberosum L. plants, and regulation of CDSP 34 expression by ABA and high illumination.

We previously described the accumulation of a 34 kDa thylakoid protein, named CDSP 34 for chloroplastic drought-induced stress protein, in Solanum tuberosum plants subjected to water deficit. A full-length CDSP 34 cDNA has been isolated and we report here that mature CDSP 34 is highly similar to two chromoplastic proteins, fibrillin from Capsicum annuum and CHRC (for chromoplast protein C) from Cucumis sativus, components of carotenoid-accumulating structures. Northern and Western analyses showed that both CDSP 34 transcript and protein accumulated from early stages of water deficit. In water-stressed tomato plants, similar increases in the CDSP 34-related transcript amount were noticed in wild-type and ABA-deficient flacca mutant, but protein accumulation was observed only in wild-type, suggesting a posttranscriptional role of ABA in CDSP 34 synthesis regulation. Substantial increases in CDSP 34 transcript and protein abundances were also observed in potato plants subjected to high illumination. The CDSP 34 protein is proposed to play a structural role in stabilizing stromal lamellae thylakoids upon osmotic or oxidative stress.

Abscisic Acid↗
PubMed1998

[Eosinophilic gastroenteritis: an example of gastrointestinal toxicity of eosinophils].

Toxicity of polynuclear eosinophils in the digestive tract results from a cascade of immune responses involving various mediators including mastocytes and T-lymphocyte helpers. Polynuclear eosinophils may be implicated in many digestive disorders. This involvement is well established in eosinophilic gastroenteritis which has become the model for study of eosinophil toxicity on the digestive tract. Considered to be of uncertain etiology up until 1998, this mechanism is well illustrated by the case described in this report involving infiltration of all layers of the small intestinal mucosa in a 23-year-old patients who responded well to corticosteroid treatment. This case provides the opportunity to update physiopathologic and therapeutic data concerning this unpredictable syndrome. Current evidence of transition forms from idiopathic hypereosinophilic syndrome casts doubt on the conventional classification of eosinophilic gastroenteritis and underlines the need for careful diagnostic work-up and prolonged follow-up.

Abdominal Pain↗
PubMed1998

[Treatment of post menopausal osteoporosis with intravenous pamidronate in patients with esophagogastric pathology].

Pamidronate is an effective inhibitor of bone resorption; for this reason it is used in the treatment of high bone turnover diseases and osteoporosis. Because of potential gastric and esophagic side effects their oral use is limited in patients with active pathology in these organs. With the aim to evaluate the usefulness and to establish the ideal schedule of treatment of intravenous pamidronate, we assayed pamidronate infusions (APDIV) in 20 postmenopausal women with active gastroesophagical diseases. Ten of these patients received 30 or 45 mg weekly until they achieved an average dose of 157.50 +/- 9.28 mg/year in one month (range: 120-180 mg) (Group A). Another comparable ten women's group received 30 or 45 mg every three months or 90 mg every six months; the achieved average dose in this group was 166.50 +/- 6.87 mg/year (range: 120-180 mg) (Group B). All patients received 1,000 mg elemental calcium daily. Bone mineral density in lumbar spine significantly increased in both groups, but this increment (delta DMO%) was higher in group B. Bone mineral density in femoral neck was only increased in group A. Parathyroid hormone (iPTH) significantly increased at the third month but returned to basal values at the end of the year in both groups. Parameters of bone remodeling such as osteocalcin (BGP), pyridinoline and deoxipyridinolin decreased progressively and remained low at the end of the year. The treatment was well tolerated: only two patients in group A and one in Group B experienced fever and pseudoflu syndrome; phlebitis was present in one patient in the second group. In conclusion, intravenous Pamidronate is an effective and safe treatment for postmenopausal osteoporosis specially in these patients with esophagicor gastric disorders. Future trials are needed to clarify the ideal dose and schedule of treatment.

Aged↗
PubMed1997

[Helicobacter pylori infection in developing countries].

Helicobacter pylori infection is probably the most common bacterial infection in the world. The pathogenicity of this bacteria has been recognized since 1989 in the developed world where prevalence is 20 to 40%. Its role in gastric and duodenal disease is certain and its low recurrence rate justifies eradication. In the developing world prevalence of Helicobacter pylori infection is over 80% with contamination being maximal in children. Transmission is oro-oral and even feco-oral. Crowded living conditions is the determinant factor. Helicobacter pylori infection exhibits special features in developing world. The prevalence of gastroduodenal disease varies according to geographic area independently of the prevalence of Helicobacter pylori infection and stomach cancer is uncommon. In newborns Helicobacter pylori infection seems to be the primary event for chronic malnutrition and diarrhea syndrome with failure to thrive. In practice detection of Helicobacter pylori is difficult in the developing world and presumptive treatment is always followed by recurrence. In the future active or passive immunization will be the solution.

Adolescent↗