Search PubMed⌕ Search

Biomedical subjects

D Gaillard

Publications and source records attributed to D Gaillard.

At least 91 records · Page 5Linked to original sources
PubMed1991

Control of terminal differentiation of adipose precursor cells by glucocorticoids.

The role of glucocorticoids on adipose conversion has been studied using confluent Ob1771 mouse preadipose cells maintained in a serum-free culture medium able to support the emergence of early but not that of late markers of differentiation. Under these culture conditions, glucocorticoids play, at physiological concentrations, a permissive role for terminal differentiation, characterized by glycerol-3-phosphate dehydrogenase expression and triacylglycerol accumulation within 12 days, whereas progesterone, testosterone, and estradiol are inactive. Glucocorticoids behave as mitogenic-adipogenic stimuli able to trigger growth-arrested, early marker-expressing cells to enter the terminal phase of the differentiation program and thus appear to mimic the mitogenic-adipogenic activity already described for arachidonic acid and cyclic AMP-elevating agents, especially prostacyclin. When compared to corticosterone alone, exposure of Ob1771 cells to both corticosterone and arachidonic acid leads to an additional increase in the glycerol-3-phosphate dehydrogenase activity and number of differentiated cells; this potentiation is further enhanced when the culture medium is supplemented with the cyclic AMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. This suggests indirectly the involvement of prostacyclin as a metabolite of arachidonic acid able to induce cyclic AMP accumulation. In agreement with this hypothesis, it is found that a promoting effect is exerted by corticosterone on the metabolism of arachidonic acid, leading in turn to an increase in the production of prostacyclin. These findings allow a better understanding of the role of glucocorticoids on adipose cell differentiation and explain a posteriori the effectiveness of the combination of dexamethasone-isobutyl-methylxanthine used in innumerable studies.

Adipose Tissue↗
PubMed1991

Late expression of alpha 2-adrenergic-mediated antilipolysis during differentiation of hamster preadipocytes.

In order to study the ontogenesis of the beta- and alpha 2-adrenergic control of lipolysis during the adipose conversion process, a model based on preadipocytes isolated from the stromal-vascular fraction of hamster adipose tissue was developed. When cultured in an ITT (insulin, transferrin, triiodothyronine) medium supplemented with 2% fetal calf serum, adipose precursors differentiated into adipose-like cells. On 8-day-post-confluent differentiating preadipocytes, the rank order of potency of activation of lipolysis by various beta-adrenergic agonists (BRL37344 greater than norepinephrine = isoproterenol greater than epinephrine greater than fenoterol) was equivalent to that determined in mature adipocytes isolated from adult hamster adipose tissue. On 8-day-post-confluent differentiating preadipocytes, phenylisopropyladenosine (A1-adenosine agonist) and prostaglandin E1 evoked a strong antilipolytic response whereas that evoked by UK 14304 and clonidine (alpha 2-adrenergic agonists) remained undetectable at this step of differentiation. The activity of UK 14304 and clonidine only appeared on 20- to 25-day-post-confluent differentiating preadipocytes. They induced dose-dependent antilipolysis with a maximal effect reaching 80-85% inhibition of adenosine deaminase-stimulated lipolysis. Their action was blocked by increased concentrations of different alpha 2-adrenergic antagonists with the following order of potency, RX 821002 greater than phentolamine much greater than yohimbine. This order of potency was similar to that determined on mature adipocytes isolated from adult hamsters. Both the density of the alpha 2-adrenoceptors, identified with the selective alpha 2-adrenergic radioligand [3H]RX-821002 (19 +/- 1 vs. 30 +/- 1 fmol/mg protein: P less than 0.01) and the amount of Gi proteins identified by pertussis toxin-catalyzed ADP-ribosylation (31 +/- 4 vs. 43 +/- 4% of the amount defined in mature fat cells from adult hamsters: P less than 0.05) were significantly increased between 8 days and 20-25 days after confluence, explaining the late emergence of the alpha 2-adrenergic control of lipolysis during preadipocyte differentiation. In conclusion, the late emergence of the alpha 2-adrenergic control of lipolysis, which is also supported by previous data obtained in vivo that demonstrated the age and/or the fat cell size dependence of alpha 2-adrenoreceptor expression in mature adipocytes, allows the alpha 2-adrenoceptor to be considered as a marker of adipocyte hypertrophy.

Adipose Tissue↗
PubMed1991

Comparison of different types of cardioplegia and reperfusion on myocardial metabolism and free radical activity.

Current techniques of myocardial protection during global ischemia include hypothermia, cardioplegic arrest and controlled reperfusion. To compare different types of cardioplegia and reperfusion techniques we measured the levels of adenine nucleotides and malondialdehyde (MDA, as free radical activity) in 33 patients undergoing heart surgery. The patients were randomized in three groups according to the characteristics of cardioplegia and reperfusion: cold blood cardioplegia with unmodified blood reperfusion (control group, 11 patients), crystalloid cardioplegia and reperfusion (Hôpital Lariboisière protocol, 11 patients) and crystalloid cardioplegia with allopurinol enriched blood reperfusion (Hôpital Broussais protocol, 11 patients). Myocardial biopsy specimens were obtained before cardioplegic arrest (preischemic values), at the end of ischemia and after 30 minutes of reperfusion. Biopsy specimens were analyzed by high performance liquid chromatography for levels of adenine nucleotides and MDA. In the three groups, the preischemic values of adenine nucleotides and MDA were not significantly different. For AMP and ADP concentrations neither treatment nor biopsy-time effects appeared. ATP concentration decreased significantly with biopsy-time without specific treatment effect. For MDA concentration neither treatment nor biopsy-time effects were observed. This study suggests that there is no statistically significant difference between any of the three cardioplegia and reperfusion techniques for either ATP or MDA; the three reperfusion techniques limit the free radical activity but do not prevent the fall in high energy phosphates.

Adenine Nucleotides↗
PubMed1991

[Value of coronary reperfusion in cases of very low cardiac output following coronary artery bypass grafts].

From January 1986 to December 1988, 244 patients had a coronary artery revascularization at St Joseph Hospital. Four patients (1.8%) died in post operative time (less than 30 days). None died directly from cardiogenic shock. Five patients had a severe low cardiac output (2 h to 48 h post-op) and needed cardiac resuscitation. These patients were immediately taken to the operating room. The coronary bypasses were explored (2 technical errors corrected), the metabolic disorders were treated and a coronary reperfusion was done with the Buckberg's technique. All the patients could be weaned from cardiopulmonary bypass, two with intra aortic balloon pumping. One patient died of digestive complication the 10th postoperative day. The four other patients survived and are in good clinical condition. The severe low cardiac output after coronary revascularization can be reversible with resuscitation in operating room, short assistance, and coronary reperfusion.

Aged↗
PubMed1990

Functional activity of ciliated outgrowths from cultured human nasal and tracheal epithelia.

Primary cultures of respiratory epithelium were produced as outgrowths from human fetal and adult tracheal and nasal polyp explants. Video recordings of the epithelial cell outgrowths were carried out after 5 days of culture and the ciliary beating frequency was analyzed by using a video technique. Uniform fields of differentiated ciliated cells were observed near the edge of the explant. In the transition region of the outgrowth from the explant to the outgrowth periphery, isolated ciliated cells were present, as well as cells with fused cilia. The ciliary beating frequency of the outgrowth of well-differentiated ciliated cells (13.5 +/- 1.4 Hz) was significantly higher (p less than 0.001) than the beating frequency of both the explant (11.9 +/- 0.7 Hz) and the ciliated cells with fused cilia (9.8 +/- 1.7 Hz). The same differentiation stages and functional activities were observed in the outgrowth cultures, whatever their origin. These in vitro models are comparable with each other and therefore could be useful for studying the ciliogenesis and functional activity of the human respiratory epithelium.

Cilia↗
PubMed1990

[Mucin histochemistry of the digestive tract in the human fetus].

Mucin secretion was studied in the gastric, intestinal, left colic and/or rectal mucosa of 42 human fetuses ranging in age from 10 to 41 weeks of gestation (menstrual age). Several histochemical techniques were used at different pH to demonstrate neutral mucins, sialomucins and sulphomucins (Periodic Acid Shiff (PAS) with and without amylase, Alcian Blue (BA) pH 2.5, pH 1 with and without hyaluronidase, BA/PAS pH 2.5 and High Iron Diamine (HID)/BA). The gastric mucosa showed mixed neutral/acid secretions during the second term. The neutral mucins increased during the 3rd term when acid mucins fell and represented only 20 percent of the secretions by the end of gestation, as during the neonatal period. These mixed secretions closely reassembled the intestinal metaplasia described in inflammatory or tumoral lesions of the stomach. The intestinal mucosa secreted mucins as early as 10 weeks before the gastric and rectal mucosa. There were neutral and acid mucins, but unlike in adults, the sulphomucins were secreted by the goblet cells of the villous and crypt epithelia. The secretions of the rectal mucosa were acid and the sulphomucins increased in quantity from 14 to 26 weeks of gestation. The HID positive sulphomucins diffused into the meconium, and probably modified the physical and chemical properties of meconium and influenced anal continence.

Age Factors↗
PubMed1990

Intrauterine versus postnatal repair of created pulmonary artery stenosis in the lamb. Morphologic comparison.

Experimental lamb models were used for intrauterine creation of pulmonary artery stenosis and later intrauterine repair or postnatal repair. Intrauterine creation of pulmonary artery stenosis was performed in 23 fetal lambs at 90 +/- 1 days of gestation. Eight lambs underwent intrauterine repair of pulmonary artery stenosis at 135 +/- 1 days of gestation and were studied 110 +/- 13 days after repair. Seven lambs underwent postnatal repair at 57 +/- 9 days after birth and were studied 162 +/- 32 days after repair. Eight fetal lambs with unrepaired pulmonary artery stenosis were studied 89 +/- 18 days after birth. All study lambs were compared with normal control lambs. The systolic right ventricular pressure was significantly higher after unrepaired stenosis (78.6 +/- 6.8 mm Hg) than in other lambs, but there was no statistically significant difference after intrauterine repair (23.3 +/- 2.9 mm Hg), postnatal repair (25.9 +/- 3.4 mm Hg), and normal lambs (21.6 +/- 1.1 mm Hg). The systolic pulmonary artery pressure was also not statistically different in these three groups. The weight measurements were age-adjusted for comparison of postnatal and intrauterine repair with normal lambs. The adjusted heart weights were similar in the three groups. The comparison of the adjusted heart weight/adjusted body weight ratio (10(-3) showed a significantly higher ratio in postnatal repair (7.4 +/- 0.1) than in intrauterine repair (6.1 +/- 0.1). The adjusted right ventricular weight/adjusted left ventricular weight ratio was significantly higher in the postnatal repair group (0.71 +/- 0.01) than in both the intrauterine repair group (0.59 +/- 0.01) and normal lambs (0.59 +/- 0.01). The transverse myocyte diameter was not statistically different in all groups of animals and there were no ultrastructural changes even when the pulmonary stenosis was unrepaired. We conclude that intrauterine repair was more satisfactory than postnatal repair in terms of age-adjusted heart weight results, but we did not find any advantages of intrauterine repair in terms of histologic and ultrastructural changes.

Animals↗
PubMed1990

[Peroperative autologous transfusion in cardiac surgery. Course, medical and economic evaluation. Prospects].

The authors report their experience since 1979 in the utilization of a system for blood salvaging in cardiac surgery. An initial comparative study showed that the patient group in which blood salvaging was used, received only 0.8 unit of red cells per patient and per hospitalisation and 50% of patients required no transfusion. In the patients receiving ATS, postoperative bleeding was significantly decreased. To confirm the advantages of the technique, a group of 200 patients was studied, consisting of 28 children and 172 adults. Hemodilution was difficult to perform in children weighing less than 15 kg. Nevertheless, ATS allowed for a significant reduction in the number of red cell units transfused. In the adult group, homologous blood consumption was 0.3 unit per patient and per hospitalization. 83% of the patients received no red cells, and 93% had no need for FFP. This reduction in homologous blood transfusion ensures a reduction in the transfusional risk. An improvement in these results will be obtained by a better organization of preoperative ATS and of the retrieval of postoperative blood.

Adolescent↗
PubMed1990

Monitoring of blood gases during extracorporeal circulation with an artificial lung.

During cardiopulmonary bypass, the heart-lung machine and the patient's gas exchange systems (uptake and elimination) form an undissociable couple. Changes in one of the components lead to corresponding changes in the other. In the artificial lung, like in the natural lung and peripheral tissues, gas exchanges depend on several parameters: blood inlet conditions, blood flow rate, temperature, composition of the gas mixture used for ventilation, blood tissue perfusion, O2 consumption, etc. The perfusionist's primary objective is to obtain from the artificial lung adequate O2 delivery to and CO2 removal from the tissues. This paper discusses the main parameters which must be taken into account and analyses the main sensors currently available for in-line measurement of blood gases.

Blood Gas Analysis↗
PubMed1989

Requirement and role of arachidonic acid in the differentiation of pre-adipose cells.

The terminal adipose differentiation of Ob1771 cells, characterized by glycerol-3-phosphate dehydrogenase activity and triacylglycerol accumulation, was studied in serum-free hormone-supplemented medium containing growth hormone, tri-iodothyronine, insulin, transferrin and fetuin. Arachidonic acid was able to substitute for a crude adipogenic fraction isolated from fetal bovine serum but not for growth hormone or tri-iodothyronine. Arachidonic acid was also able to increase in a rapid and dramatic manner cyclic AMP production; moreover it was able to amplify the adipose conversion promoted by other agents elevating cyclic AMP concentrations and to induce inositol phospholipid breakdown. Both phorbol 12-myristate 13-acetate, a protein kinase C activator and ionomycin, a Ca2+-mobilizing agent, showed potent synergy with agents elevating cyclic AMP concentrations for the promotion of adipose conversion, whereas 8-bromo cyclic GMP and 4 alpha-phorbol 12,13-dibutyrate were ineffective. The triggering of both the cyclic AMP and inositol phospholipid pathways was accompanied by a single round of cell division, and within a few days all the cells became differentiated. Similar results were obtained, after exposure to arachidonic acid, with preadipose 3T3-F442A cells and with rat adipose precursor cells in primary culture. The availability of arachidonic acid from intracellular stores and/or of exogenous origin should play a major role for the onset of critical mitoses leading to terminal differentiation in pre-adipose cells.

Adipose Tissue↗
PubMed1989

Prostacyclin as a potent effector of adipose-cell differentiation.

The terminal differentiation of Ob1771 pre-adipose cells induced by arachidonic acid in serum-free hormone-supplemented medium containing insulin, transferrin, growth hormone, tri-iodothyronine and fetuin (5F medium) was strongly diminished in the presence of inhibitors of prostaglandin synthesis, namely aspirin or indomethacin. Carbaprostacyclin, a stable analogue of prostacyclin (prostaglandin I2) known to be synthesized by pre-adipocytes and adipocytes, behaved as an efficient activator of cyclic AMP production and was able, when added to 5F medium, to mimic the adipogenic effect of arachidonic acid. Prostaglandins E2, F2 alpha and D2, unable to affect the cyclic AMP production, failed to substitute for carbaprostacyclin. However, prostaglandin F2 alpha, which is another metabolite of arachidonic acid in pre-adipose and adipose cells, able to promote inositol phospholipid breakdown and protein kinase C activation, potentiated the adipogenic effect of carbaprostacyclin. In addition, carbaprostacyclin enhanced both a limited proliferation and terminal differentiation of adipose precursor cells isolated from rodent and human adipose tissues maintained in primary culture. These results demonstrate the critical role of prostacyclin and prostaglandin F2 alpha on adipose conversion in vitro and suggest a paracrine/autocrine role of both prostanoids in the development of adipose tissue in vivo.

Adipose Tissue↗
PubMed1989

Promoting effect of glucocorticoids on the differentiation of human adipocyte precursor cells cultured in a chemically defined medium.

Stromal-vascular cells obtained from adult human subcutaneous adipose tissue were cultured in a chemically defined serum-free medium. In the presence of 0.2 nM triiodothyronine and 0.5 microM insulin, up to 25% of the cells were able to undergo terminal adipose differentiation within 18 d, as assessed by lipid accumulation and the expression of lipoprotein lipase (LPL) and glycerol-3-phosphate dehydrogenase (GPDH) activities. Addition of cortisol resulted in a potent dose-dependent stimulation of the adipose differentiation process. Cortisol could be replaced by dexamethasone and partly by aldosterone, but not by sex steroids. The proportion of differentiated cells was dependent upon the age of the donor; when isolated from young adults, up to 70% of the stromal-vascular cells expressed the adipocyte phenotype as compared with 5-10% when the cells were isolated from the oldest subjects. An inverse relationship was observed between the age of the 27 normal-weight donors and the extent of GPDH expression after maintenance of the cells for 18 d in chemically defined medium supplemented with insulin, triiodothyronine, and cortisol (r = -0.787, P less than 0.001). It is concluded that adult human adipose tissue still contains precursor cells that are able to undergo adipose differentiation in vitro. This improved culture system may offer the opportunity to characterize other adipogenic factors as well as antiadipogenic factors involved in the control of adipose tissue growth.

Adipose Tissue↗
PubMed1989

Coupling growth arrest and adipocyte differentiation.

The complete differentiation program of preadipose cells can be divided into early and late events. The expression of early markers takes place at growth arrest (G1/S boundary), whereas that of late markers, leading to terminal differentiation, takes place after a limited number of mitoses of early marker-containing cells. Only terminal differentiation requires the presence of growth hormone and triiodothyronine and results in the formation of triacylglycerol-filled, nondividing cells. The events of adipose cell differentiation which take place in vitro allow a better understanding of the development of adipose tissue in vivo.

Adipose Tissue↗
PubMed1989

[Liposarcoma in children. Apropos of 3 cases and a review of the literature].

Liposarcoma is an uncommon tumour in childhood. Three cases are reported. Two patients remain alive and well without local recurrence or metastasis following the initial treatment, however one patient died as a result of direct tumour extension despite chemotherapy. A review of the literature revealed the following features: the extremity are the most common location, the predominance of myxoid histology and its best prognosis. The treatment is the complete surgical excision, the efficiency of radiotherapy or chemotherapy has not been formally proved.

Buttocks↗
PubMed1988

Infantile familial encephalopathy with cerebral calcifications and leukodystrophy.

Two sets of siblings, in two different families, presenting with congenital and progressive neurological disorders, cerebral calcifications and leukodystrophy are reported. In the first family, the diagnosis of brain calcifications in two infants was based on skull X-rays; in the second family, ultrasound scans showed hyperechoic areas in the basal ganglia and periventricular white matter in both infants. Neuropathological studies confirmed the calcifications and revealed severe abnormalities of the white matter with GFAP positive gliosis. Electron micrographs showed large astrocytes with an increased amount of glial filaments. In the group of idiopathic non arteriosclerotic cerebral calcifications, these four cases may represent a separate entity with possible autosomal recessive inheritance.

Age Factors↗
PubMed1988

Cardiac pacing and valvular surgery.

Over a 17-year period (1970-1987) 75 patients, 3% of overall valvular surgery (VS) patients have been permanently paced at the time of VS (group 1), nine have been paced long after (group 2), 12 were already paced at the time of valve replacement (group 3), and 81 had a permanent pacing lead inserted during VS without further need for permanent pacing (group 4). Based on pre-, per- and post-operative clinical and electrocardiographic data we studied these four groups (GR). Aortic disease and especially calcified aortic stenosis (CAS) are the main valvular pathologies in all GR. The survival rate in GR 1 is lower than the survival rate of our overall VS PT5 due to older average ages and more severe cardiac conditions. In five patients GR 2 a myocardial pacing lead placed during VS was used long after for permanent stimulation. Patients in GR 3 were older than in other GR at the time of VS. The mortality was high in the patients operated on between 1973 and 1978 (average survived 3.5 years after pacing/2 years after VS) thus demonstrating the benefit of myocardial protection. For GR 4 the ratio of permanent lead implantation during VS was high in the late seventies (10%), it is now around 0.5%. In cases where the evolution of peroperative conduction disturbances is doubtful, it seems to us simpler to place a myocardial lead avoiding subsequent endocardial pacing if necessary, later, especially in patients with tricuspid disease.

Aged↗
PubMed1988

[Distribution of fibronectin and laminin during development of the human myenteric plexus and Hirschsprung's disease].

The distribution of fibronectin and laminin, two glycoproteins involved in the migration of neural crest cells, was studied by an indirect immunohistofluorescence technique in 35 embryos and fetuses (from 6 weeks old to birth), 5 normal controls, and 6 patients with Hirschsprung's disease, in order to provide a new approach to the embryogenesis of human myenteric plexus and the pathogenesis of aganglionosis. Fibronectin was not seen near individual neuroblasts unlike myoblasts and mesenchymal cells which were surrounded by this macromolecule. There was a progressive and parallel cephalocaudal development of the plexus and the muscular layers from the esophagus to the intestine. However, in the rectum, at 7 weeks, neuroblasts were detected in close contact to fibronectin-labeled cells whereas they were not in the colon. These present results were in favor of two origins for neuroblasts: the vagal and the caudal neural crest cells. Faulty migration of caudal neural crest cells might be involved in the aganglionosis of Hirschsprung's disease in spite of the fact that local environment of fibronectin and laminin was identical to that of normal subjects.

Adult↗