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Biomedical subjects

M Laurent

Publications and source records attributed to M Laurent.

At least 145 records · Page 8Linked to original sources
PubMed1991

[Removal of an anatomic post].

Removing an anatomical cast post requires many precaution and, in most situation, gives very good results. Nevertheless, this procedure can be dangerous for the tooth or the surrounding tissues and must be considered only in case of absolute necessity. Two techniques are described using a little hole made in the coronal part of the core. A threaded wire is driven through this hole making possible the use of a crown remover. For the second technique the use of an original appliance, the ATD bridge remover, is demonstrated with very good results too.

Dental Instruments↗
PubMed1991

[Stenosis of the branches of the pulmonary artery caused by Hodgkin's lymphadenopathies].

A 22 year old patient was admitted to hospital for dyspnoea and haemoptysis. Cardiac catheterisation showed a pressure gradient between the main pulmonary artery and its branches. Pulmonary angiography showed appearances of extrinsic compression of the branches of the pulmonary artery. This was shown to be caused by lymphadenopathy on CT scan and Hodgkin's disease was diagnosed after surgical biopsy. The pressure gradient between the main pulmonary artery and its distal branches almost completely regressed after chemotherapy and radiotherapy.

Adult↗
PubMed1991

[Rationale in implant prosthetics].

Today, it is quite easy, even to the unfamiliar practitioner in implantology, to get clear ideas of the surgical stage in treatments where implants are involved. These procedures have been well described and documented, especially by the swedish school. But things are less simple concerning the prosthetical procedures. After a personal experience of years, in this field, both, as oral surgeon and prosthodontist, we think time has come to point out several criterias, leading to long range success. We will review some major aspects of this particular prosthodontics, like: different clinical situations, according to the localisation of edentulism, connections, frameworks and cosmetics, and so on... We are convinced that the respect of these rules is one of the numerous keys of success in today's implantology.

Dental Implantation, Endosseous↗
PubMed1990

Localization of acidic fibroblast growth factor (aFGF) mRNA in mouse and bovine retina by in situ hybridization.

Acidic fibroblast growth factor (aFGF) mRNA has been detected in adult mouse or bovine retina by in situ hybridization with bovine aFGF cDNA clones. It is localized on ganglion cell layer, inner nuclear layer, photoreceptors and slightly on pigmented epithelium. This synthesis of aFGF in highly specialized retinal cell types is discussed in the framework on current views about the role of FGF in retinal cell biology.

Animals↗
PubMed1990

Human beta-fibrinogen gene expression. Upstream sequences involved in its tissue specific expression and its dexamethasone and interleukin 6 stimulation.

The synthesis of fibrinogen in the liver is drastically enhanced during the inflammatory process. Two factors are involved: glucocorticoids and the hepatocyte stimulating factor which is identical with interleukin 6 (Il6), also called interferon beta 2. The function of the 5'-flanking region of the human beta-fibrinogen (beta-Fg) gene has been studied by deletion analysis with the chloramphenicol acetyltransferase (CAT) gene as a transient expression vector. In this analysis, a fragment containing 150 base pairs (bp) upstream from the cap site is sufficient to drive expression of the CAT gene in the hepatoma cells HepG2, but not in HeLa cells. The beta-Fg gene is induced by dexamethasone and Il6 in HepG2. We identify a domain located between -2900 and -1500 bp upstream from the transcription start point involved in dexamethasone sensibility. This distal regulatory region can confer hormone inductibility to a heterologous promoter and exert its effect in either orientation. The sequence located between -150 and -82 bp upstream from the transcription start point is responsive for the Il6-stimulated expression. This 68-bp sequence contains probably all the cis-acting Il6-responsive element of the human beta-Fg gene.

Base Sequence↗
PubMed1990

Basic fibroblast growth factor expression in human omental microvascular endothelial cells and the effect of phorbol ester.

The human omentum contains a potent, not yet identified angiogenic activity. The omentum is very vascularized. Therefore, we investigated whether human omental microvascular endothelial cells (HOME cells) express the angiogenic peptide basic fibroblast growth factor (bFGF). Cytosol prepared from HOME cells stimulated DNA synthesis in bovine epithelial lens cells (BEL cells). The mitogenic activity could be neutralized by an anti-bFGF antibody. Basic FGF-like material from the HOME cell cytosol was bound onto a heparin-Sepharose column at 0.6 M and was eluted at 3 M NaCl. The 3 M NaCl eluted material reacted with the specific anti-bFGF antibody in an ELISA and stimulated DNA synthesis. It did not react with a specific anti-acidic fibroblast growth factor (aFGF) antibody. Western blotting experiments using the same bFGF antibody showed the presence of a major band of 17 Kd and a doublet of 20-22 Kd. Northern blotting of non-stimulated HOME cells using a specific 1.4 kb bFGF probe showed the presence of 5 molecular species of 6.6, 3.7, 2.2, 2.0, and 1.0 kb. No aFGF mRNA was detected with a specific previously characterized 4.04 kb probe. 12-O-tetradecanoylphorbol 13-acetate (TPA) did not influence significantly the expression of bFGF at the protein and mRNA level in HOME cells. Thus, protein kinase C activation by TPA did not appear to modulate significantly the expression of bFGF for that cell type. Contrastingly, human umbilical vein endothelial cells (HUVE cells), which expressed no bFGF and aFGF mRNA at a basal level, were induced to express bFGF but not aFGF mRNA when stimulated by TPA. These results suggest that the described angiogenic activity could be the bFGF-like mitogen contained in HOME cells and that these cells are different from endothelial cells derived from large vessels (HUVE cells) regarding the expression of bFGF.

Biological Assay↗
PubMed1990

Analysis of lens protein synthesis in a cataractous mutant mouse: the Cat Fraser.

The cataract produced by the dominant Cat Fraser gene in mouse is associated with quantitative changes in lens proteins (crystallin) and with capsule abnormalities. We have analyzed and compared the protein synthesis in control and mutant lenses using [3H]leucine and [3H]proline incorporation. The specific activities of free [3H]leucine in the intracellular pools of the two mouse strains were identical, while the incorporation of both labelled amino acids in proteins was largely increased in Cat Fraser lens. These data indicate that the higher labelling of Cat Fraser lens proteins reflects a true change in the cellular synthesis activity by Cat Fraser lens cells. Despite the enhanced type IV collagen synthesis by Cat Fraser epithelial cells, the amount of type IV collagen in Cat Fraser capsule is lower than in control. This altered type-IV collagen metabolism may disturb the structure of Cat Fraser capsule which becomes thicker.

Animals↗
PubMed1990

[Carney's triad: a new case associated with adrenal cortex adenoma].

Carney's triad is a combination of at least 2 of 3 tumor sites: multiple gastric leiomyoblastoma, pulmonary chondroma and paraganglioma, most often extra-adrenal and secreting. Thirty-three cases have been published; we report a new case in a 20 year-old woman, with multiple gastric leiomyoblastomas, liver metastasis, and bilateral pulmonary chondroma. The research of paraganglioma, in regard to Carney's disease, led to the discovery of corticoadrenal adenoma.

Adenoma↗
PubMed1990

[Breast microcalcifications without palpable tumor detected using mammography. Anatomo-pathologic study technique].

Screening mammograms to detect early non palpable breast cancers will hopefully diminish the breast cancer mortality rate. However, proper pathologic examination of mammographically directed breast biopsies is mandatory. Sampling of a specimen containing microcalcifications should be directed by examination of the specimen radiogram. Frozen section of non palpable foci of microcalcifications is never performed. Thorough localization and sampling of the microcalcified lesions permit the detection of very small cancers usually of the intraductal type.

Breast Diseases↗
PubMed1989

Detection by in situ hybridization of messenger RNAs of collagen types I and IV in murine mammary cancer.

Ten breast carcinomas developing in C3H/Bi female mice were studied by an in situ hybridization technique using cDNA probes encoding alpha-I chains of collagens of types I and IV. The results obtained are compared to histochemical data on antibodies to collagens of types I and IV and ultrastructural observations on these tumors. Immunohistochemistry has revealed the presence of type-IV collagen in basement membranes lining intraductal and well-differentiated cancer nests. Type-I collagen was detected in the stroma surrounding these cells. There was no cellular labelling when these antisera were used. In situ hybridization has shown that type-IV collagen mRNA is detected in non-invasive intraductal and well-differentiated tumor cells and in endothelial cells in the stroma. Good correlation between detection of type-IV collagen lining these cells and evidence of mRNA by in situ hybridization was thus observed. Invasive cancer cells did not express hybridization grains with the type-IV collagen probe. Type-I collagen mRNA was visualized in stromal cells, probably fibroblasts and myofibroblasts as shown by electron microscopy. The most active cells were localized close to non-invasive areas. Our data indicate persistent in-vivo biosynthesis of type-IV collagen by some cancer cells that produce their own limitative environment; they suggest that type-IV collagen is not produced by invasive tumor cells and that stromal cells lining the non-invasive regions have a peculiar behavior.

Animals↗
PubMed1989

Increased sensitivity of various genes to endogenous DNase activity in terminal differentiating chick lens fibers.

In the lens, epithelial cells from the equatorial zone differentiate into postmitotic elongated fibers. One aspect of this differentiation is nuclear shape transformation and DNA degradation. This process is controlled by DNase activity which in fiber nuclei increases with development. DNase activity is also present in the epithelial cell nuclei which appears to be non-functional but could be activated in vitro by exogenous addition of Ca2+. We have analyzed the possible selective action of endogenous DNase on 3 genes involved in lens terminal differentiation, namely delta-crystallin, beta-tubulin and vimentin, and on 1 gene not thought to participate in this process, ovalbumin. We have compared restriction DNA patterns of these genes in nuclei isolated from 11-day-old chick embryos and incubated in Ca2+-free medium or in fresh epithelial and fiber lens tissue at 11 and 18 days of development. During incubation in vitro of 11-day fiber nuclei, there is a net increase in the sensitivity of the delta-crystallin, beta-tubulin, ovalbumin and vimentin chromatin to the endogenous DNase. The vimentin gene appears to be more stable than the beta-tubulin and delta-crystallin genes indicating a degree of specificity of the endogenous DNase activity. In the epithelial nuclei, the lens-specific genes appear to be more stable but paradoxically there is a net degradation of the ovalbumin gene. In freshly isolated tissues the 4 genes were detected in epithelial and fiber cells at 11 and 18 days. Furthermore, in the mature fibers in which the nuclei were degenerating, the latter genes were still not completely digested.

Animals↗
PubMed1989

Relationship between primitive reflexes, extra-pyramidal signs, reflective apraxia and severity of cognitive impairment in dementia of the Alzheimer type.

Controversy exists in the literature about the significance of primitive reflexes (PR) and extrapyramidal signs (EP) as diffuse cortical dysfunction signs and their relationship to age and cognitive impairment. A sample of 91 patients with a dementia of the Alzheimer type were examined with a standardized technique to assess the relationship between the finding of PR, EP and severity of cognitive impairment measured by Mini-Mental Status Examination. The value of a short cognitive test, the reflective apraxia (i.e. imitation of meaningless gestures), were also assessed. A significantly lower MMS score was correlated with the number of present PR and with presence of snout, sucking and grasping reflexes. No correlation was found between presence or absence of PR and age, depression, or drug therapy. EP score was correlated with the number of present PR and MMS, but not with age. Reflective apraxia score was significantly correlated with the degree of cognitive impairment and was found with lower cognitive impairment than PR.

Aged↗
PubMed1989

Current biotechnological developments in Belgium.

In recent years, actions have been undertaken by the Belgian government to promote process innovation and technical diversification. Research programs are initiated and coordinated by the study committee for biotechnology setup within the Institute for Scientific Research in Industry and Agriculture (IRSIA). As a result of this action, the main areas where biotechnological processes are developed or commercially exploited include plant genetics, protein engineering, hybridoma technology, biopesticides, production by genetic engineering of vaccines and drugs, monoclonal detection of human and animal deseases, process reactors for aerobic and anaerobic wastewater treatment, and genetic modification of yeast and bacteria as a base for biomass and energy. Development research also includes new fermentation technologies principally based on immobilization of microorganisms, reactor design, and optimization of unit operations involved in downstream processing. Food, pharmaceutical, and chemical industries are involved in genetic engineering and biotechnology and each of these sectors is overviewed in this paper.

Agriculture↗
PubMed1989

[AIDS in elderly patients. Apropos of 22 cases observed in the Paris region].

If geriatric AIDS is defined as the occurrence of this disease in individuals over 60 years old, it represents about 5% of the cases reported to the Direction Générale de la Santé by the end of 1988. We retrospectively analyzed 22 clinical cases of geriatric AIDS observed between 1985 and 1987, i.e. 21% of the cases reported at that time. In 55% of them, infection resulted from contaminated blood transfusions. Initially, hospitalization was indicated due to a significant deterioration of the patient's general condition, however, neuropsychiatric disorders and intellectual degeneration were present in 18% of the cases. Biological anomalies at the time of admission were classical with the exception of a high frequency of leukopenia often associated with anemia or thrombopenia. During the evolution of the disease, opportunistic infections were very common (90% of the cases). However, the major characteristic of this clinical form of AIDS is the high percentage (55%) of patients suffering from major neurological and psychiatric disorders, including subacute encephalitis in more than half of these patients. The prognosis is very bad, with an average survival time of 4.3 months from the time of diagnosis (median 2.5 months). The cumulative effect of the delay in diagnosing AIDS during the first hospitalization and the classical seriousness of encephalitis suffice to explain the very poor prognosis in patients whose age can play a role in altering the immune response.

AIDS Dementia Complex↗
PubMed1989

[Rhabdomyosarcomas discovered in newborn infants. Study of markers of muscle differentiation].

Rhabdomyosarcomas were observed at birth in two premature infants. The evolution of these tumors was both rapid and fatal. One case was a botryoid sarcoma of the bladder and the second was a cervical alveolar sarcoma of Riopelle and Thériault. A cytological differentiation of the tumor was observed in the first case spontaneously and in the second following chemotherapy. In the second case histology, immunocytochemistry and a novel biochemical analysis of the contractile proteins demonstrated this differentiation of the tumor. The cellular reactivity varies according to the degree of muscular differentiation that can be defined either by studying the type of intermediate filaments present or the expression of specific muscle contractile proteins.

Female↗
PubMed1989

[A case of epidermoid carcinoma developing from contact with an articular hip prosthesis].

Several cases of sarcomas which developed in contact with joint prosthetic material were reported previously. They were mostly malignant fibrous histiocytoma, but to our knowledge, no case of epidermoid carcinoma was reported. We report here one case of epidermoid carcinoma which developed in contact with a hip prosthesis. Surgery was complicated by local infection and necessitated multiple reoperations, which may be responsible for the implantation of skin cells. It is generally admitted that multiple factors contribute to the development of a tumor clone. In our patient we must take into consideration such factors as chronic infection with fistula and prosthetic material. However carcinomas, even rare, which form on fistulas appear only after many years of suppuration. The short delay between the prosthesis setting and the carcinoma onset in our patients, suggests that a cofactor may have speeded up tumor induction. This cofactor could be the platelet derived growth factor (PDGF) in the case of sarcomas appearing on bone infarcts without foreign body introduction, and possibly other tumors.

Bone Neoplasms↗