Biomedical subjects

N Saidi

Publications and source records attributed to N Saidi.

6 recordsLinked to original sources

PubMed2003

Microbial and copper adsorption by smectitic clay--an experimental study.

The objective of this study was to quantify copper-, bacteria- and bacteriophage-binding capacities of natural clay with the aim of predicting the adsorption of heavy metals, human pathogenic bacteria and viruses by a clayey landfill liner. X-ray diffraction analysis of six natural clays showed that the dominant phase in all deposits consists of smectites together with illite, kaolin and, sometimes, palygorskite and sepiolite. The specific surface areas of different clay substrates were very high ranging from 293 to 351 m2 g(-1), and indicating a high proportion of phyllosilicates, consisting especially of smectites. The physico-chemical identification of separated smectites showed a high potential adsorbent character indicative of a large industrial use. The Kb12 smectite substrate chosen arbitrarily among six separated substrates, appeared as an excellent copper adsorbent. Copper was adsorbed to clay in a proportion ranging from 94.6 to 96.0% with an average of 95.1% and its adsorption occurred rapidly in less than 30 min. Organic contents of the clay substrate, evaluated as 17% of dry mass, may contribute and enhance copper adsorption. Different elution protocols using distilled water, 2 and/or 5% nitric acid revealed that while nitric acid resulted in the removal of more than 59% of the metal at the lower concentration and its complete depletion with a further elution at the higher concentration, distilled water alone was unable to remove more than 1% of adsorbed copper. This finding suggested that copper ions form high-energy bonds with layer-silicate surfaces. Interestingly, the use of a regenerated substrate as copper adsorbent subsequent to abundant washings of the used substrate consecutively, with 0.1 N HNO3 and distilled water, reduced copper adsorption by approximately 14%, suggesting a slight disturbance of clay initial structure. Batch adsorption experiments with phage T7 and raw clay Kb12 showed that the tested clay substrate appeared as a relatively moderate phage adsorbent since the quantity of adsorbed phage averaged 98.2 +/- 0.88% (2 log10 retention) as measured by infectivity for Escherichia coli ATCC 11303. As shown by two types of separating procedures, natural sedimentation and a low speed centrifugation, bacteriophage particles were bound essentially to fine and not to relatively coarse particles of the clay suspension. The retention capacity of purified clay Kb12 appeared low, with average values lower than 60 and 50%, for Pseudomonas aeruginosa ATCC 15442 and Bacillus cereus ATCC 1135, respectively. A significant increase of retention, in the order of 30%, was found for both bacteria when the mixture clay-bacteria was incubated at laboratory temperature for 6 hours.

Adsorption↗

PubMed1999

Lebetase, an alpha(beta)-fibrin(ogen)olytic metalloproteinase of Vipera lebetina snake venom, is inhibited by human alpha-macroglobulins.

The effects of the plasma proteinase inhibitors alpha(2)-macroglobulin (alpha(2)M) and the alpha(2)M-related pregnancy zone protein (PZP) were evaluated towards the metalloproteinase lebetase, isolated from Vipera lebetina venom. We demonstrate that lebetase interacts with both inhibitors. Cleavage of alpha(2)M by lebetase resulted in the formation of 90-kDa fragments, and covalent complexes of alpha(2)M with lebetase were observed. The proteolytic activity of lebetase against fibrinogen and azocasein could be inhibited by alpha(2)M. Cleavage of PZP also resulted in the formation of 90-kDa fragments, and complexes of both dimer and tetramer forms of PZP with lebetase were detected. The amino acid sequence identification of the sites of specific proteolysis of alpha(2)M and PZP demonstrate that the cleavage sites are within the bait regions of both proteins. Lebetase I cleaves between Arg(696)-Leu(697), which is one of the most common cleavage sites in alpha(2)M by proteinases. The other two cleavage sites in alpha(2)M by lebetase are Gly(679)-Leu(680) and His(694)-Ala(695). The cleavage between Pro(689)-Gln(690) is the only cleavage site identified in PZP. In that lebetase is an anticoagulation agent in vivo, we propose that the interaction of lebetase with alpha(2)M may suggest a reduced fibrin(ogen)olytic activity of lebetase in human.

Amino Acid Sequence↗

PubMed1999

Nitrous oxide increases endotracheal cuff pressure and the incidence of tracheal lesions in anesthetized patients.

UNLABELLED: The pressure in air-filled endotracheal cuffs increases steadily throughout general anesthesia with nitrous oxide (N2O). High cuff pressures can be responsible for local ischemia, which may induce tracheal mucosal injury. In this study, cuff pressure was monitored in anesthetized patients, and postanesthesia endotracheal lesions were assessed by endoscopy. Sixty-five patients undergoing general anesthesia with tracheal intubation >1 h in duration were randomized into two groups. The endotracheal tube cuff was inflated to 30-40 cm H2O with air in Group 1 (n = 33) and with a gas mixture (N2O 50% in oxygen) in Group 2 (n = 32). At the time of tracheal extubation, a fiberoptic examination via the endotracheal tube was performed by an independent observer. Aspects of trachea at the level of cuff contact area were scored as 0 = normal, 1 = mucosal erythema or edema, 2 = mucosal erosion or hemorrhage, 3 = mucosal erosion or hemorrhage on both anterior and posterior tracheal walls. Cuff pressure increased throughout the procedure (P<0.01) in Group 1 and remained stable in Group 2. In Group 1, tracheal lesions in the area of the cuff were more frequent than they were in Group 2 (79% vs. 37%; P<0.001). Tracheal injury was correlated to cuff pressure (r = 0.62, P<0.001). No postoperative respiratory complication was observed in any patient. In patients anesthetized with N2O, the inflation of the tracheal tube cuff with a gas mixture of the same composition as the inhaled mixture can prevent excessive cuff pressure and reduce the incidence of tracheal injury. IMPLICATIONS: In patients anesthetized with nitrous oxide, the inflation of the tracheal tube cuff with a gas mixture of the same composition as the inhaled mixture can prevent excessive cuff pressure and reduce the incidence of tracheal injury.

Adult↗

PubMed1984

The role of the glycoconjugates in the migration of anuran amphibian germ cells.

The presence of a large amount of glycoconjugates on the anuran amphibian germ cells was demonstrated using fluorescein isothiocyanate lectins binding specifically to D-galactose and at a lower level, by other lectins binding specifically to N-acetyl-galactosamine. Glycoconjugates including D-galactose were found near the pseudopodial expansions and in the extracellular space, between germ cells and follicular cells. They were also disseminated in the cytoplasm. The injection of PNA lectin (from Arachis hypogea) into the endoderm inhibited the migration of 90% of the germ cells. This inhibition was lectin-concentration dependent. Ultrastructural study of germ cells, the migration of which was inhibited, showed that they were degenerating. These results suggest that glycoconjugates are related to the migratory activity of germ cells.

Acetylgalactosamine↗

PubMed1982

[Detection, using fluorescent lectins, of specific carbohydrate chains in primordial germ cells of anuran amphibians].

A study of primordial germ cells (PGC) of Amphibia Anura was carried out after treatment of sections by different fluorescein isothiocyanate conjugated lectins (FITC-lectins). Specific labelling on the PGC is obtained with lectins, the activity of which is inhibited by D-galactose or N-acetyl-galactosamine. These osidic groups appear to be located more specifically on the PGC. The same labelling pattern is not obtained with lectins possessing major affinity for mannose, glucose, fucose and N-acetyl-glucosamine. Furthermore, changes in labelling pattern are observed during migration of PGC. It is suggested that D-galactose and N-acetyl-galactosamine might be related to membrane activity of PGC during migration. Ultrastructural study of the visualization of cell surface carbohydrates supplies some information on the localisation of these lectins receptors.

Animals↗

PubMedDate not supplied

[Isolation of salmonella in wastewaters and study of indicator bacteria survival in soils].

Detection of salmonella in wastewaters was done in semi-industrial pilot plant. In parallel, survival of indicator bacteria (feacal coliforms and feacal streptococci) in the soil was evaluated into a laboratory incubation device. Results revealed the isolation of 21 strains of salmonella in 7 campaigns of analysis on DCLS media, and 6 strains on lactose-green-brilliant and phenol red media in 2 campaigns. Salmonella were recovered in all the lines of wastewater treatment. The study led on the survival of coliforms and streptococci bacteria allowed the conclusion that feacal streptococci introduced by wastewaters were more qualified to survive in the soil than feacal coliforms. On the other hand, feacal coliforms appeared more sensitive to the biological factors of the soil than feacal streptococci. The ambient temperature of incubation situated between 12 and 24 degrees C seemed suitable for bacteria survival in the soils.

Enterobacter↗