Biomedical subjects

D Gaillard

Publications and source records attributed to D Gaillard.

At least 73 records · Page 4Linked to original sources

PubMed1994

[Quantification of DNA using image analysis on paraffin sections].

With the new softwares that are available, it is now possible to measure the cellular DNA content on Feulgen stained paraffin sections, without enzymatic dissociation of the samples. The main advantage of this technique is to preserve the cellular histological context and to select the right cells that have to be analyzed. The application is of course to obtain information about cancer prognosis, but it can also be very useful in non tumoral pathology. The DNA measurement on paraffin sections can be applied to the diagnosis of triploidy or tetraploïdy in spontaneous abortions without any karyotype.

DNA↗

PubMed1994

Use of chromosome painting for marker chromosome identification in two children with congenital disorders.

Identification of supernumerary de novo marker chromosomes was considered up to now as difficult and sometimes impossible with classical cytogenetical banding methods. The determination of their chromosomal origin is now easier with fluorescent in situ hybridisation techniques and enables an exact correlation between chromosomal aberration and phenotypic features to be established. The authors describe the use of chromosome painting with chromosome 13 and 18 Whole library DNA probe for identification of supernumerary markers in tow patients with congenital disorders. Cytogenetic examination in the first cave revealed a mosaicism with a ring chromosome 13 but clinical findings were different from the classical "ring 13 syndrome', and chromosome painting revealed in an extra--dicentric 13 chromosome (mos : 47, XX, -13, +r (13) +dic (13) / 46, XX, r (13) / 45, XX, -13 / 48, XX, -13, +r (13), (12) dic (13) / 47, XX, -13, + (2) r (13), R-banding pattern on prometaphases and chromosome painting in the second case confirmed the marker to be a 18 p isochromosome (47, XX, +i (18p)). The feasibility and the usefulness of chromosome painting in ascertainment of the possible genetic significance of markers is discussed.

Chromosome Banding↗

PubMed1993

Differential expression of adenosine A1 and A2 receptors in preadipocytes and adipocytes.

Multiple physiological functions have been described to be affected by adenosine in numerous cell types. A comparative study of the expression of adenosine receptors has been performed in preadipocytes and adipocytes from rat epididymal fat pad. The results show that, in agreement with its well known antilipolytic effect, adenosine induces a negative modulation of adenylate cyclase via the A1 receptor present in adipocytes. By contrast, the A2 receptor subtype, which is positively coupled to adenylate cyclase, is herein demonstrated to be only expressed in adipose precursor cells. This expression allows, in chemically defined medium, the adenosine analogue NECA, by means of its ability to elevate cAMP concentration, to potentiate differentiation. These findings emphasize the role that adenosine might play as a bimodal regulatory extracellular signal in adipose tissue development.

Adenosine↗

PubMed1993

Inhibition of prostacyclin-induced Ca2+ mobilization by phorbol esters in Ob1771 preadipocytes.

In addition to cAMP production, a transient elevation of intracellular free Ca2+ has been shown to take place in preadipose cells upon stimulation by carbaprostacyclin (cPGI2), both messengers acting in synergy to initiate adipose cell differentiation (Vassaux, G., Gaillard, D., Ailhaud, G., and Négrel, R. (1992) J. Biol. Chem.267, 11092-11097). Further studies reported herein show that this Ca2+ transient is i) elicited by the natural prostaglandin PGI2, ii) independent of the presence of extracellular Ca2+, suggesting a mobilization of Ca2+ from intracellular pools and ii) unaffected by cAMP elevating agents. Moreover, and in contrast to the InsP3-dependent Ca2+ signal evoked by PGF2 alpha, that induced by PGI2 is fully abolished by pretreatment with phorbol esters (EC50: 1-5 nM). Furthermore, experiments designed to empty the Ca2+ pools, using PGI2 or PGF2 alpha as Ca2+ mobilizing agents as well as pretreatments with drugs, allow to conclude that PGI2 mobilizes Ca2+ from an InsP3 sensitive, ryanodine insensitive intracellular pool. Altogether, these results strongly suggest that PGI2 mobilizes Ca2+ from an intracellular store common to that affected by InsP3, by means of a mechanism which remains to be elucidated.

1-Methyl-3-isobutylxanthine↗

PubMed1993

Terminal differentiation of mouse preadipocyte cells: adipogenic and antimitogenic role of triiodothyronine.

The role of triiodothyronine (T3) in the differentiation process of Ob1771 mouse preadipocyte cells has been studied under serum-free and hormone supplemented culture conditions which were previously shown to lead to terminal differentiation. In the absence of T3, a dramatic decrease in the adipogenic activity of the culture medium (EC50 = 0.1 nM) could be observed, as indicated 12 days after confluence by the low levels of late markers of differentiation such as adipsin, lipid-binding protein aP2 and glycerol-3-phosphate dehydrogenase as well as the sharp reduction of the number of triacyglycerol-containing cells. This decrease in adipogenic activity was accompanied by a parallel increase of the mitogenic potency of the culture medium. Therefore, T3 appears to be a hormone capable of modulating both proliferation and differentiation of preadipocytes. T3 ceased to be necessary provided the culture medium was supplemented with high concentrations of inducers of differentiation, such as 8-bromo-cAMP or carbaprostacyclin.

1-Methyl-3-isobutylxanthine↗

PubMed1993

Tubule formation by human surface respiratory epithelial cells cultured in a three-dimensional collagen lattice.

Human surface respiratory epithelial (HSRE) cells from nasal polyps have been cultured within collagen lattices in a serum-free defined medium. Cell growth observed over a period of 12 days showed a population doubling time of 36 h. Under these culture conditions, we observed a contraction of the lattices. Phase-contrast light microscopy and transmission electron microscopy demonstrated that the HSRE cells formed tubular ductlike structures. Lumens formed by HSRE cells were surrounded by cuboidal-shaped polarized cells with numerous ciliated cells, secretory cells, and undifferentiated cells. Epidermal growth factor (EGF) was observed to stimulate the tubule formation and the contraction of the lattices. Videomicroscopic observations and analysis of the ciliary beating frequency (CBF) demonstrated that the cilia were homogeneously distributed on the whole apical surface of the ciliated cells and that their movement was well coordinated, with a CBF similar to that observed in outgrowth cells from cultured human nasal and tracheal epithelia. Immunofluorescent staining of basement membrane components synthesized and secreted by cells revealed the presence of type III collagen around the tubules. Type IV collagen and laminin were present in the cytoplasm and at the periphery of the cells. The biotin-streptavidin-gold immunocytochemical technique with monoclonal anti-mucin antibody showed intracellular localization of mucins in secretory granules of the secretory cells. With the use of substrate gel electrophoresis polyacrylamide gels impregnated with gelatin, collagenase activity was detected in the conditioned medium of the cultured HSRE cells. These results suggest that both three-dimensional collagen gel and soluble factors such as EGF regulate tubule formation by HSRE cells. Moreover, the capacity of the epithelial cells to contract the gel suggests they may be involved in the wound healing process.

Basement Membrane↗

PubMed1993

The influence of tissue pretreatment on the immunohistochemical demonstration of type I and III collagens and tenascin in fetal human tooth germs.

The influence of tissue pretreatment on the PAP immunostaining for type I and III collagens and tenascin was studied in formalin-fixed and paraffin-embedded human tooth germs at the 24th and 25th weeks of fetal life. Three variables were considered: the type of buffer used (PBS or Tris), pepsin digestion and the use of normal serum as a blocking agent prior to immunostaining. All three proteins needed an enzymatic digestion to be intensely revealed. Pepsin promoted, even at low concentrations, an intracellular staining of type I collagen in the secretory odontoblasts and in the pulpal fibroblasts. Normal serum partially blocked unspecific immunoreaction when polyclonal rabbit antibodies were used. The Tris buffer increased the staining intensity of the three macromolecules and revealed an unusual tenascin-like immunoreactivity in the ameloblasts. This study demonstrated that pepsin digestion and the use of normal serum and different buffers may influence the immunoreactivity of ECM proteins.

Buffers↗

PubMed1993

[Development and maturation of secretory cells in the trachea of human fetuses].

The number of tracheal epithelial secretory cells and their mucus secretions change during the course of human foetal development. The muco-secretory cells of the respiratory mucus and glands were studied in the trachea in 46 human foetuses with the aid of histochemical techniques, and ultrastructural examination. During the second trimester of pregnancy, the mucosecretory cells are very numerous in the surface epithelium for a transitory period, and secrete as much neutral mucin as acid mucin; these latter were predominantly sulphomucins. The glands appear progressively from the 13th week of development and remain almost exclusively of the mucous type until the second trimester. During the third trimester the serous cells appear but their number remains low. The mucosecretory surface epithelial cells are rare in this trimester but produce the same type of secretions. The role of secretory cells in utero in the foetus is poorly understood. Foetal secretions differ from the normal adult mucus cells but approach them with qualitative and quantitative differences observed in the mucus of irritated bronchi or those with scarring.

Embryonic and Fetal Development↗

PubMed1993

Extracorporeal circulation in European Economic Community (ECC in EEC): 1979-1989.

This study determines the evolution of ECC in EEC. After recollecting the great stages of ECC since its routinely use in open heart surgery, the study situates its position in the entire world taking into account several indexes like the Gross National Product (GNP) and its evolution, the life expectancy and some other factors either technical or economical. Only a coarse analysis could be done for Europe due to an unsteady evolution. A more detailed analysis has been achieved for France thanks to a greater number of data. In such a study the major difficulty is to estimate the relevance and consistency of data which can change very quickly and are provided either by companies or by other organization.

Economics↗

PubMed1992

Prostacyclin is a specific effector of adipose cell differentiation. Its dual role as a cAMP- and Ca(2+)-elevating agent.

The mitogenic-adipogenic activity of carbaprostacyclin (cPGI2), a stable analogue of prostacyclin (PGI2), has been proposed to be related to its ability to elicit cAMP production and to activate the protein kinase A cascade (Négrel, R., Gaillard, D., and Ailhaud, G. (1989) Biochem. J. 257, 399-405). In the present study, cPGI2 has been compared with other activators of the cAMP pathway, namely isoproterenol, forskolin and 8-bromo-cAMP, with respect to adipose cell differentiation. Carbaprostacyclin behaved as a much more potent and efficient effector of mouse Ob1771 preadipocyte differentiation than the latter agents. Moreover, cPGI2 also exerted a specific amplifying mitogenic-adipogenic role, as compared with isoproterenol in rat as well as human adipose precursor cells in primary culture, suggesting that the prostanoid was able to generate an additional second messenger. The fact that ionomycin was able to potentiate and amplify the differentiation induced by 8-bromo-cAMP led us to give evidence, using preadipocytes preloaded with the fluorescent calcium chelator Indo-1, that cPGI2, besides its ability to activate adenyl cyclase, was also able to induce a transient increase in intracellular free calcium. This phenomenon was independent of cAMP production or inositol phospholipid breakdown and appeared to be mediated after binding to a single class of PGI2 receptor. The potential to generate simultaneously two synergistic intracellular signals allows us to ascribe to PGI2 a key and specific role in the differentiation of adipose precursor cells in vitro that would likely lead in vivo to the recruitment of "dormant" preadipocytes to become adipocytes.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1992

Differential localization of the cystic fibrosis transmembrane conductance regulator in normal and cystic fibrosis airway epithelium.

Deletion of the amino acid residue Phe 508 of the cystic fibrosis transmembrane conductance regulator (CFTR) protein represents the most common mutation identified in cystic fibrosis (CF) patients. A monoclonal and a polyclonal antibody directed against different regions of CFTR were used to localize the CFTR protein in normal and CF airway epithelium derived from polyps of non-CF and CF subjects homozygous for the delta Phe 508 CFTR mutation. To identify the cellular and subcellular localization of CFTR, immunofluorescent light microscopy, confocal scanning microscopy, and immunogold transmission electron microscopy were performed on cryofixed tissue. A markedly different subcellular distribution was identified between normal and CF airway epithelial cells. In normal epithelium, labeling was restricted to the surface apical compartment of the ciliated cells. In contrast, in the epithelium from homozygous delta Phe 508 CF patients, CFTR markedly accumulated in the cytosol of all the epithelial cells. These findings are consistent with the concept that the CFTR delta Phe 508 mutation modifies the intracellular maturation and trafficking of the protein, leading to an altered subcellular distribution of the delta Phe 508 mutant CFTR.

Cystic Fibrosis↗

PubMed1992

Differential response of preadipocytes and adipocytes to prostacyclin and prostaglandin E2: physiological implications.

The major prostaglandins (PGs) locally produced in adipose tissue both in rodent and man are PGE2 and prostacyclin (PGI2). We have recently described PGI2 as an autocrine promoter and/or amplifier of terminal differentiation of cultured preadipocytes in several species. The effectiveness and specificity of PGI2 as an adipogenic agent are related to its ability to induce in preadipocytes intracellular increases of both cAMP and free calcium. Moreover, PGs of the E series are well known to exert an antilipolytic effect in mature adipocytes. These observations have prompted us to address two questions of physiological interest: 1) Is PGI2 still able to increase cAMP in differentiated adipocytes, behaving thus as a lipolytic agent, and 2) Is PGE2 able to negatively modulate cAMP production in adipose precursor cells, behaving thus as a counteracting effector of PGI2 action? Our results, with respect to cAMP production and/or lipolysis and antilipolysis, demonstrate clearly that in adipose tissue of both rat and man, PGI2 exclusively affects adipose precursor cells whereas PGE2 exclusively affects adipocytes. We propose a model of concerted action for both PGs in the development of adipose tissue mass, PGI2 behaving as an adipogenic-hyperplastic effector and PGE2 as an antilipolytic-hypertrophic effector.

Adipose Tissue↗

PubMed1992

Terminal differentiation of mouse preadipocyte cells: the mitogenic-adipogenic role of growth hormone is mediated by the protein kinase C signalling pathway.

The role of growth hormone (GH) in the differentiation process of Ob1771 mouse preadipocyte cells has been studied under culture conditions that were serum-free and hormone-supplemented and which were previously shown to lead to terminal differentiation. In the absence of GH, a dramatic decrease in the adipogenic activity of the culture medium could be observed, as indicated 12 days after confluence by the low levels of glycerol-3-phosphate dehydrogenase activity and the sharp reduction of the number of triacylglycerol-containing cells. This decrease in adipogenic activity was accompanied by a parallel loss of the mitogenic potency of the culture medium. Determination of the half-maximal and maximal concentrations of GH required for the restoration of growth and differentiation were identical, 0.5 and 2 nM, respectively. Despite the presence of insulin-like growth factor-I (IGF-I) to substitute for supraphysiological concentrations of insulin and to saturate IGF-I receptor, GH was still required to induce terminal differentiation of a maximal number of cells. However, protein kinase C activators such as prostaglandin F2 alpha, phorbol esters and diacylglycerol were able to mimic GH in promoting a maximal mitogenic-adipogenic response, indicating that the ability of GH to induce diacylglycerol production (Doglio et al., 1989; Catalioto et al., 1990) plays a prominent role in this process. Furthermore, in agreement with the fact that the mitoses which precede terminal differentiation of Ob1771 preadipocytes are strictly controlled by cAMP and only modulated by protein kinase C, terminal differentiation of Ob1771 preadipocytes occurred in the absence of GH upon supplementation with high concentrations of carbaprostacyclin, added as a cAMP-elevating agent or with 8-Br-cAMP, added as a cAMP analogue. It is concluded that the control exerted by GH on terminal differentiation of mouse preadipocytes corresponds to a modulating mitogenic effect mediated through protein kinase C activation and leading to a potentiation of the cAMP and IGF-I mitogenic signalling pathways.

Adipose Tissue↗

PubMed1992

[Decrease of postoperative morbidity in coronary surgery using the two internal mammary arteries].

The surgical risk of bilateral internal mammary artery grafting was analyzed in 100 successive patients separated chronologically into two groups. These groups were not statistically different in terms of age, severity of angina, and extent of coronary artery disease. The number of grafts per patient and the time of aortic cross clamping were not statistically different in the two groups. The postoperative mortality was 1% in the 100 patients. The incidence of perioperative myocardial infarction was not statistically different in the two groups. No mediastinal suppuration was observed. The mean postoperative hemorrhage was 633 +/- 558 ml in the first 50 patients and 560 +/- 410 ml for the last 50 patients (p < 0.05). The percentage of patients receiving no homologous blood transfusion was 64% in the first 50 patients and 94% in the last 50 patients. The percentage of phrenic palsy was 36% in the first 50 patients and 6% in the last 50 patients (p < 0.05). With surgical experience, the risk of coronary bypass with bilateral internal mammary artery was lowered and very similar to the surgical risk of conventional aorto-coronary bypass with saphenous veins or one mammary artery.

Adult↗

PubMed1992

[Coronary artery bypass with 2 internal mammary arteries. Early clinical and angiographic results in 100 patients].

One hundred patients underwent coronary revascularisation with both internal mammary arteries between 1987 and 1990. The average age of the patients was 55 years. The left internal mammary was used in 97 of the 100 cases as a pediculated graft to revascularise the left anterior descending (66 cases), left lateral (27 cases) or a bissecting artery (4 cases). The right internal mammary was used as a pediculated graft in 51 cases and as a free graft to revascularise a left lateral (51 cases), left anterior descending (29 cases) or right coronary artery (20 cases). There was one death in the first 30 postoperative days. Morbidity was low with no cases of sternal infection. The average postoperative bleeding was 633 +/- 550 ml per patient. The incidence of phrenic nerve paralysis decreased from 36% in the first 50 patients to 6% in the second 50 patients. Angiography at the 10th postoperative day showed 4 occlusions out of 132 internal mammary arteries opacified (97% patency). Ninety four patients are asymptomatic and have negative exercise stress tests. Mortality and morbidity of coronary surgery using the two internal mammary arteries are therefore the same as those of conventional coronary surgery using saphenous veinar only one internal mammary artery, providing that it is reserved for patients in good general condition, under 65 years of age, without obesity or diabetes. This technique of coronary artery revascularization should provide better long-term results because of the high patency rate of the grafts.

Adult↗

PubMed1992

Human airway secretory cells during development and in mature airway epithelium.

The combined secretions of distinct secretory cells of the airway lining mucosa serve to keep the inspired air moist and free of potentially harmful dust particles, organisms and adsorbed gases. Apart from their role in protecting the respiratory zone of the lung, mucus-secreting cells act as pluripotential stem cells during foetal development and, in the adult, following mucosal injury. The variety of secretory cells include the mucous and serous cells of the surface and glandular epithelium, the non-ciliated bronchiolar (Clara) cell and the less frequent dense-core granulated (neuroendocrine) cell. The last-mentioned is the first type to differentiate at about 10 weeks of gestation; mucus-secreting cells are present from the 13th week of gestation, when mature ciliated cells are already present, and Clara cells begin to mature during the 19th week of human development. The alteration of secretory cell number and chemical composition of their secretions during the second trimester of foetal life is similar to that which occurs in chronic bronchitis in the adult. However, in hypersecretory disease the extent and site of the major change appear to be inappropriate to the defence of the lung.

Epithelial Cells↗

PubMed1992

[Use of extracorporeal circulation oxygenators (CEC) in the European Economic Community (EEC)].

This study analyses the growth of CPB in the EEC. The study situates its position in the world taking into account several indexes such as the Gross National Product and its growth the life expectancy and other technical or economic factors. Only a broad analysis could be performed for Europe to the irregular development of CPB. A more detailed analysis was performed for France thanks to a greater number of data. In this type of study the most important problem is to estimate the relevance and consistency of the data provided either by companies or by other organizations because they can change very quickly.

Cardiopulmonary Bypass↗

PubMed1991

Autocrine control of adipose cell differentiation by prostacyclin and PGF2 alpha.

The mitogenic-adipogenic effect exerted by arachidonic acid, which leads to terminal differentiation of Ob1771 mouse preadipocytes, has been shown to be (i) blocked by cyclooxygenase inhibitors, (ii) mimicked by a stable analogue of prostacyclin (carbaprostacyclin) and (iii) potentiated by PGF2 alpha. Since these prostanoids are known to be synthesized and secreted by preadipocytes, we have proposed that both prostacyclin as the key mediator and PGF2 alpha as a modulator control the expression of terminal events of adipose conversion by means of an autocrine mechanism (Gaillard, D. et al. and Negrel, R. et al. Biochem. J. (1989) 257, 389-397 and 399-405). In order to test this hypothesis, the release of prostacyclin, characterized under the form of its stable degradation product 6-keto-PGF1 alpha, and that of PGF2 alpha have been studied in the culture medium of Ob1771 cells. A striking increase in the release of 6-keto-PGF1 alpha and to a minor degree of PGF2 alpha was observed when cells were exposed to arachidonic acid as shown by using [3H]arachidonic acid prelabelled cells or by radio-immunoassays. Since antagonists of PGF2 alpha and PGI2 receptors were not available, specific antibodies directed against PGF2 alpha and 6 beta-PGI1, another stable analogue of prostacyclin, were added as neutralizing agents in the culture medium. These antibodies were able to counteract the mitogenic-adipogenic effect of arachidonic acid. Prostacyclin and PGF2 alpha thus appear as autocrine mediators in the process of adipose conversion.

Adipose Tissue↗