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Biomedical subjects

G Guillemin

Publications and source records attributed to G Guillemin.

At least 19 recordsLinked to original sources
PubMed1997

Obtention and characterization of primary astrocyte and microglial cultures from adult monkey brains.

Simple methods for obtention of primary cultures of isolated astrocytes and microglia from adult simian brain have been developed. Characterization of these two glial cell populations were performed by morphological observations and by immunocytochemistry. The astroglial cultures were obtained by an indirect method. After L-leucine methyl-ester treatment and trypsinizations, more than 99% of cells expressed glial fibrillary acidic protein (GFAP), whereas no macrophages or microglia could be detected. Likely, the 1% remaining cells were immature astrocytes or cells that lost their GFAP expression. Cultured simian astrocytes expressed vimentin, laminin, and fibronectin. We also found a constitutively low expression of major histocompatibility complex (MHC) class II by cultured astrocytes which was significantly enhanced by lipopolysaccharide (LPS), interferon gamma (IFN-gamma), or tumor necrosis factor alpha (TNF-alpha) treatments. Microglial cultures were obtained by a direct method of isolation using Percoll gradient separations and compared to simian monocyte-derived macrophages or alveolar macrophages. Microglial cells differed from macrophages by their proliferation upon granulocyte-macrophage colony stimulating factor (GM-CSF) treatment and by their typical morphology when observed by scanning electron microscopy. As macrophages, they expressed in vitro CD68, CD64, CD14, CD11b, MHC class II, and fibronectin. However, contrary to macrophages, simian cultured microglia expressed laminin. This observation suggests that microglia represent a new potential source of this extracellular matrix protein in the brain.

Animals↗
PubMed1996

Molecular characterization of beta-thalassemia mutations in Guadeloupe.

In order to perform genetic counselling and prenatal diagnosis of Hb-S-beta-thalassemia disease and beta-thalassemia, we have delineated the spectrum of beta-thalassemia alleles in the Guadeloupean population. A sample of 63 unrelated families was analyzed including 70 beta-thalassemia carriers, 52 Hb-S-beta-thalassemia, and 8 patients with different beta-thalassemic hemoglobinopathies. Among the eleven mutations identified, four of them [-29 (A --> G), IVS-I-5 (G --> A), IVS-II-1 (G --> A), and IVS-I-5 (G --> C)] account for 77.6% of the beta-thalassemia chromosomes present in the studied families. The seven other variants, CD 24 (T --> A), IVS-I-2 (T --> C), Poly A (T --> C), -88 (C --> T), IVS- 11-849 (A --> G), Hb E, and Hb Lepore are less frequent. As a result, Hb S-beta+-thalassemia type 1 (low Hb A values: 5-15%) together with Hb S-beta(omicron)-thalassemia phenotypes are as frequent as Hb S-beta+-thalassemia type 2 (high Hb A values: 20-30%) in the Guadeloupean population. Patients with Hb S-beta+-thalassemia type 2 have milder hematological manifestations of the disease compared to patients with Hb S-beta(omicron)-thalassemia and Hb S-beta+-thalassemia type 1. This first report on the type and nature of beta-thalassemia mutations in Guadeloupe shows that prenatal diagnosis of Hb S-beta-thalassemia and beta-thalassemia should be feasible by direct detection of point mutation in most cases.

Africa, Western↗
PubMed1996

Granulocyte macrophage colony stimulating factor stimulates in vitro proliferation of astrocytes derived from simian mature brains.

In the brain, granulocyte-macrophage colony stimulating factor (GM-CSF) may be released by infiltrated cells of the immune system including T and B lymphocytes and mononuclear phagocytes, but also by nervous system resident cells such as microglia and astrocytes. Astrocyte-secreted GM-CSF may play an important role in enhancing the local inflammatory response to central nervous system (CNS) injury and in recruting microglia and activated macrophages. In this study, we demonstrated that GM-CSF, as TNF alpha and IL 6, stimulates in vitro proliferation of simian astrocytes in primary cultures. Results were confirmed by blocking experiments performed with a specific neutralizing mAb directed against GM-CSF. Furthermore, we demonstrated that GM-CSF mediates its effect on these cells through the alpha subunit of the GM-CSF receptor which is constitutively expressed at the membrane of the cultured simian astrocytes as assessed by immunofluorescence. GM-CSF effects on astrocytes could be involved in astrocytosis, a hallmark of various neurological injuries and in inflammatory processes in an autocrine manner.

Animals↗
PubMed1996

[Isolation, culture and characterization of astrocytes from adult monkey brains].

We have developed protocols for the isolation, the culture and the immunocytochemical characterization of astrocytes from simian adult brains. We have obtained pure astrocyte cultures without contamination with other cells present in brain. No microglial cells, oligodendrocytes, neurons or fibroblasts were detected by specific staining in immunocytochemistry.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Identification of new mutations in two phosphoglycerate kinase (PGK) variants expressing different clinical syndromes: PGK Créteil and PGK Amiens.

Phosphoglycerate kinase (PGK) deficiency is generally associated with chronic hemolytic anemia, although it can be accompanied by either mental retardation or muscular disease. Genomic DNAs of two PGK-deficient patients previously described in France were sequenced directly after polymerase chain reaction amplification. The PGK Créteil variant arises from a G-->A nucleotide interchange at position 1022 in cDNA (exon 9), resulting in amino acid substitution 314 Asp-->Asn in the C-terminal domain, which contains the nucleotide binding site. It is associated with rhabdomyolysis crises but not with hemolysis or mental retardation. In the other case, which is associated with chronic hemolytic anemia and mental retardation (PGK Amiens), an A-->T nucleotide interchange was found at position 571 in cDNA (exon 5); this leads to amino acid substitution 163 Asp-->Val in the N-terminal domain, which contains the catalytic site for phosphoglycerate binding. These results corroborate the kinetic data observed. In the two cases, the mutations are distinct from others previously reported and no significant relationship could be observed between the location of the amino acid substitution and its clinical consequences.

Adult↗
PubMed1994

Evaluation of the osteogenic potential of biomaterials implanted in the palatal connective tissue of miniature pigs using undecalcified sections.

Calcium phosphate or calcium carbonate biomaterials are widely used as bone substitutes in periodontal surgery. This study evaluates the osteogenic potential of five different alloplastic biomaterials implanted in the connective tissue of the palatal papilla in miniature pigs. A porous hydroxyapatite (PHA), a dense hydroxyapatite (DHA), a semi-porous hydroxyapatite (SPHA), a tricalcium phosphate (TCP) and a calcium carbonate natural coral (NC) were implanted in a tunnel in the palatal papillae of seven miniature pigs. Undecalcified sections were examined histologically at 1, 2, 3, 4, 8, 12 and 24 wk intervals. Resorbable materials (TCP and NC) were totally resorbed by 24 wk. DHA, PHA and HA showed very limited resorption, although there were multinucleated giant cells in contact with PHA and SPHA. There was no histologically detectable bone formation in contact with or near any of the biomaterials tested. However, several particles of NC, and sometimes of PHA, were surrounded by a dense, mineralized matrix. It is concluded that none of these biomaterials, in their presently available forms, has any bone inducing capacity.

Animals↗
PubMed1993

A composite of natural coral, collagen, bone protein and basic fibroblast growth factor tested in a rat subcutaneous model.

A rat subcutaneous model was used to test the osteoinductive efficacy of a composite consisting of natural coral, collagen, a bone morphogenetic protein-like material [termed bone protein (BP)], and basic fibroblast growth factor (bFGF). Results indicated good ossicle formation only when BP was present, whether with or without bFGF. Initially, cartilage and mineralized cartilage were apparent. With time, osteoblastic bone formation and hematopoietic marrow were evident. bFGF may have enhanced the maturation of the ossicles in the early stages. Coral-collagen appears to be a good carrier vehicle for BP and should be tested in a bony site. This would allow the osteoconductive property of coral to be expressed.

Animals↗
PubMed1991

[Prevention of substance loss in an edentulous site: report of case combining gingival graft and coral particles].

Ridge collapse is often seen after tooth extraction and grafting procedure is used in this technique. This case report presents, after block section of two maxillary incisors, the use of an occlusal epithelio-connective tissue graft, followed by grafting of coral particles. Clinical results, six months post-operatively, show a total maintenance of edentulous ridge volume and height. A biopsy at the same interval shows fibrous tissue surrounding coral particles, giant cells in some areas, but also some areas of calcification.

Adult↗
PubMed1989

Comparison of coral resorption and bone apposition with two natural corals of different porosities.

Previous studies showed that natural coral implanted into bone tissue was gradually resorbed and progressively replaced by newly formed bone. The objectives of this study were to compare the fate of two Madreporian corals, Porites and Acropora, after implantation during 1 and 2 months into sheep and pig long bones. These materials are identical in composition (CaCo3) but differ in volume (49 +/- 2%, 12 +/- 4%, respectively) and mean size (250 vs. 500 microns) of porosities. The non-decalcified histological slices were observed under light microscopy. Implant resorption and new bone formation were quantified through an automatic image analysis system. Quantitative results showed that the larger the porosity volume, the greater was the coral resorption as well as the new bone apposition. Large differences were found between the two animal species. Histological findings were identical to those previously reported: implants were resorbed and progressively replaced by newly formed bone. Coral was found to be an osteoconductive biomaterial which acted as a scaffold for a direct osteoblastic apposition and consequently could be an interesting alternative to bone auto-, allo-, or xenografts.

Animals↗
PubMed1989

[Natural coral used as a replacement biomaterial in bone grafts].

Natural coral, submitted to rigorous protocols of preparation and purification, can be used as a replacement biomaterial for bone grafts both in orthopaedic surgery and maxillo-cranio-facial surgery and neurosurgery. Experimental studies commenced in 1977 and human clinical applications, commenced in 1979, have largely demonstrated the biocompatibility of the material and its entirely original nature. This biomaterial is progressively and totally replaced by newly formed bone with, after completion of the restoration process, has the characteristics of the recipient bone.

Animals↗
PubMed1989

[Coral substituted for bone grafting in posterior vertebral arthrodesis in children. Initial results].

The authors used natural coral as a substitutive element to bone supply in children in need of posterior vertebral graft. The use of natural coral was part of a protocol aiming at diminishing peroperative bleeding, and as far as possible, at doing away with resorting to homotransfusion. After reviewing the biological, experimental and clinical bases, the authors studied 49 cases of posterior vertebral fusion instrumented with the Cotrel-Dubousset device and with natural coral grafts. Results were appraised with X-ray in all cases, 5 times with scintigraphies and 7 times with biopsies and were encouraging: coral behaves quite similarly to the usual bone graft. From their experience the authors describe how coral is to be used and consider that the use of this substitutive element should spread in the future under various forms.

Animals↗
PubMed1988

Madreporic coral: a new bone graft substitute for cranial surgery.

Since 1985, the authors have been using madreporic coral fragments (genera Porites) as a bone graft substitute. Of the 167 coral grafts implanted, 150 were coral "corks" used to obliterate burr holes (diameter 10 mm), five were large implants (length 20 to 40 mm) to repair skull defects, and 12 were coral blocks to reconstruct the floor of the anterior cranial fossa. Previous experimental studies suggested that coral grafts would be well tolerated and become partially reossified as the calcific skeleton was resorbed. The authors describe their experience and detail the main biological properties of these materials, which appear to be very promising for use in cranial reconstructive surgery.

Animals↗
PubMed1988

[The coefficient of saturation of iron in transferrin].

Theoretical iron fixation capacity of transferrin (FCT) can be calculated on its immunochemical titration: (FCT (mumol/l = transferrin (g/l) x 25). Today, its reckoning is more advisable to serum total iron binding capacity measurement. The authors studied the effects of this new proceeding upon usual values interval of transferrin saturation (i.e. serum iron/FCT ratio). The mean value and the distribution of transferrin saturation appear displaced with regard to those achieved by chemical measurement of serum total iron binding capacity. We discuss interpretation of transferrin saturation related to its methods of determination and its semiological interest.

Adolescent↗
PubMed1988

[Reconstruction of the anterior face of the base of the skull using coral grafts].

Following experimental investigations on animals, small coral grafts have been utilized on patients since 1985 to fill in burr holes (42 patients). This first clinical experimental step has been satisfactory. Therefore, blocks of corals have since then been used as bone graft substitutes for anterior skull basis reconstruction (12 patients). Cheap and easily sterilized, coral implants have the advantage of being inert (99% of calcium carbonate), biodegradable and well reossified. They shorten surgical procedures by avoiding the use of iliac and/or costal grafts. No infectious complications have been noted.

Biocompatible Materials↗