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M Benaissa

Publications and source records attributed to M Benaissa.

10 recordsLinked to original sources
PubMed1999

Lactoferrin is synthesized by mouse brain tissue and its expression is enhanced after MPTP treatment.

The presence of iron in brain tissue in increased concentrations in Parkinson's disease cases, where it might be responsible for oxidative stress, and the parallel observation that the iron transporter lactoferrin (Lf) was present in increased amounts in surviving neurons, led us to study the synthesis of Lf in a mouse model of Parkinson's disease. In this context, the origin and expression of brain Lf in normal, aged and MPTP (1-methyl-4-phenyl-1, 2,3,6-tetrahydropyridine)-treated mice were investigated. Lf immunostaining was observed mainly on microvessels in the cerebral cortex of the adult mice and to a greater extent in older mice. Lf immunoreactivity was also present in the hippocampus only in the aged mouse brains, associated with structures which seemed to be pyramidal neurons and fibers. After RT-PCR (polymerase chain reaction), Lf transcripts were found in mouse brain tissue whatever the age of the animals studied but the level of their expression was very low. No up-regulation of Lf was detectable during aging. Lf distribution and expression in the MPTP-induced Parkinsonian mouse model were also investigated. A marked depletion of dopamine (DA) occurred in the high dose MPTP-treated mice. The level of Lf expression was found to be markedly increased in the same animals and this up-regulation occurred on the first day after MPTP administration. When the brain was stressed by the neurotoxin MPTP, Lf expression increased in line with antioxidant enzymes such as catalase and gamma-glutamylcysteine synthetase, which may permit the protection of brain tissue from oxidative damage induced by the drug.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1998

Lactoferrin is synthesized by mouse brain tissue and its expression is enhanced after MPTP treatment.

The biological role and origin of human lactoferrin (Lf) within the brain in normal and disease processes are as yet uncharted. In this context the origin and expression of brain Lf in normal and MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-treated mice were investigated using immunohisto chemistry, PCR amplification and in situ hybridization. Lf immunostaining was observed both on sections of mouse lactating mammary gland, which was used as a positive control, and brains from young, adult and aged mice. Lf immunoreactivity was present in the pituitary gland, the hippocampus and the cortex of mouse brains and to a greater extent in older mice. After reverse transcription, Lf transcripts were also found in these brain sections. Lf distribution and expression in the MPTP-induced parkinsonian mouse model were next investigated. A marked depletion of dopamine and its metabolites: dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy indole acetic acid (5-HIAA) occurs in the high dose MPTP-treated mice. The level of Lf expression was found to be greatly increased in the same animals but Lf immunoreactivity detected in the same brain region was not found increased in the affected areas.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

Hyperthermia complicating tricyclic antidepressant overdose.

We observed a 51-year-old woman who was admitted for severe amitriptyline overdose. Besides major cardiovascular complications, the patient developed severe hyperpyrexia with a central body temperature of more than 43 degrees C for 5 h. The patient died on day 3 from cardiocirculatory collapse and arrhythmias. Hyperthermia was unresponsive to cooling with ice water, gastric lavage, muscle relaxation, and dantrolene and bromocriptine administration. The possible mechanisms of refractory hyperthermia are discussed.

Amitriptyline↗
PubMed1996

Changes in Helicobacter pylori ultrastructure and antigens during conversion from the bacillary to the coccoid form.

In vitro, Helicobacter pylori converts from a bacillary to a full coccoid form via an intermediate U-shaped form. Organisms with a full coccoid form keep a double membrane system, a polar membrane, and invagination structures. Western blots (immunoblots) of sera from colonized patients show that some high-molecular-mass antigenic fractions are expressed only in coccoids. Conversely, fractions of 30 and 94 kDa were more intensively detected in the bacillary forms. These results suggest that (i) coccoid conversion is not a degenerative transformation and (ii) antigens specific to the coccoid forms are expressed in vivo.

Antigens, Bacterial↗
PubMed1995

Structural determination of two N-linked glycans isolated from recombinant human lactoferrin expressed in BHK cells.

A full-length cDNA coding for human lactoferrin was isolated from a mammary gland library and the recombinant protein was expressed in BHK cells as described by Stowell K. M. et al. [1991, Biochem. J. 276, 349-355]. Two N-linked glycans from purified recombinant lactoferrin were released by hydrazinolysis and analyzed by 400-MHz 1H-NMR spectroscopy. The identified structures corresponded to N-acetyllactosaminic biantennary glycans and were alpha-2,3-disialylated forms (80%) or alpha-2,3-monosialylated (20%) forms. Moreover, 70% of total glycans were alpha-1,6-fucosylated at the GlcNAc residue linked to asparagine. In regard to its glycan moiety, the recombinant glycoprotein is close to native lactoferrins from milk or leucocytes but shows specific structural features which should be taken into account prior to in vivo and in vitro biological studies.

Animals↗
PubMed1995

Rat mammary-gland transferrin: nucleotide sequence, phylogenetic analysis and glycan structure.

The complete cDNA for rat mammary-gland transferrin (Tf) has been sequenced and also the native protein isolated from milk in order to analyse the structure of the main glycan variants present. A lactating-rat mammary-gland cDNA library in lambda gt10 was screened with a partial cDNA copy of rat liver Tf and subsequently rescreened with 5' fragments of the longest clones. This produced a 2275 bp insert coding for an open reading frame of 695 amino acid residues. This includes a 19-amino acid signal sequence and the mature protein containing 676 amino acids and one N-glycosylation site in the C-terminal domain at residue 490. Phylogenetic analysis was carried out using 14 translated Tf nucleotide sequences, and the derived evolutionary tree shows that at least three gene duplication events have occurred during Tf evolution, one of which generated the N- and C-terminal domains and occurred before separation of arthropods and chordates. The two halves of human melanotransferrin are more similar to each other than to any other sequence, which contrasts with the pattern shown by the remaining sequences. Native rat milk Tf is separated into four bands on native PAGE that differ only in their sialic acid content: one biantennary glycan is present containing either no sialic acid residues or up to three. The complete structures of the two major variants were determined by methylation, m.s. and 400 MHz 1H-n.m.r. spectroscopy. They contain either one or two neuraminic acid residues (alpha 2-->6)-linked to galactose in conventional biantennary N-acetyl-lactosamine-type glycans. Most contain fucose (alpha 1-->6)-linked to the terminal non-reducing N-acetylglucosamine.

Animal Population Groups↗
PubMed1994

Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line.

In order to determine whether the human lactotransferrin receptor recently described on platelets was also present on hematopoietic precursors, we investigated its presence and characteristics on the megakaryocytic Dami cell line. The reversible binding of human 5-(([2-(carbo(hydrazino)methyl]thio)acetyl)aminofluorescein-labele d lactotransferrin showed that such a receptor was only present on the subpopulation of the largest cells. The increase in numbers of large cells during culture was paralleled by a concurrent increase in lactotransferrin receptor positive cells. Scatchard analysis of the binding of [125I]-labeled lactotransferrin showed that a single affinity class of binding site was present (Kd = 446 +/- 40 nM) and that there were 52 +/- 3 x 10(5) sites per cell. The mouse monoclonal antibody DP5B3G10, specific for the human lactotransferrin receptor, allowed its characterization as a 105 kDa protein on Western blots. The same monoclonal antibody was used to separate the small and large cell subpopulations of Dami cells by panning. Separate culture of the small cells showed that the receptor appeared prior to and independent from endomitosis. In contrast, GPIb was expressed only by large megakaryocytes. The use of conditioned medium from cultures of whole Dami cell populations indicated that a soluble factor is involved in differentiation, but not in the appearance of the lactotransferrin receptor.

Blood Platelets↗
PubMed1991

Molecular cloning and sequence analysis of bovine lactotransferrin.

The screening of a bovine submaxillary gland cDNA library yielded 25 clones coding for bovine lactotransferrin. The nucleotide sequence of the longest insert contained a protein-coding region of 2115 nucleotides and a 3' non-coding region of 194 nucleotides followed by a poly(A) tract of about 55 nucleotides. The predicted peptide sequence included a 16-amino-acid signal sequence upstream of the first amino acid of the native protein. The identity of the clone was confirmed by matching the amino acid sequence predicted from the cDNA with the N-terminal and tryptic peptide sequences derived from purified bovine milk lactotransferrin, and also by similarity with human and murine lactotransferrins. The cDNA described corresponds to a 705-amino-acid-long preprotein that lacks the start methionine. The sequence of the secreted protein is 689 amino acids long and contains five potential glycosylation sites. Bovine lactotransferrin is 69% and 64% identical to human and murine lactotransferrins, respectively.

Amino Acid Sequence↗