Bilateral skeletonized mammary artery grafting: experience with 560 consecutive patients

OBJECTIVE

To test the hypothesis that the skeletonized technique of harvesting the internal thoracic artery improves the surgical results of bilateral internal thoracic artery grafting, we reviewed our 7-year experience with this technique.

METHODS

Between July 1987 and December 1994, 560 patients received bilateral internal thoracic artery grafts and 236 additional grafts (average 2.6 +/- 0.6 anastomoses per patient). There were 515 men (92%) and the average age was 56.9 +/- 8.8 years. There were 63 diabetic patients (11.3%). During harvesting, the internal thoracic arteries were always totally skeletonized from the surrounding tissues without the use of electrocautery.

RESULTS

Postoperative complications included reoperation for bleeding, 17 patients (3%), phrenic nerve paresis, 17 patients (3%), acute respiratory distress syndrome, 9 patients (1.6%), digestive complications, 8 patients (1.4%), neurologic complications, 6 patients (1.1%), and sternal complications, 6 patients (1.1%). No wound complications were observed in diabetic patients. The hospital mortality rate was 1.6% (9 patients, 2 cardiac causes). The early patency of internal thoracic artery grafts was 97.9%. Follow-up averages 29 +/- 20 months. There were 14 late deaths (4 cardiac causes). Angina recurred in 51 patients and the maximal stress test was abnormal in 47 patients.

CONCLUSION

Bilateral internal thoracic artery grafting with skeletonized harvesting carried low post-operative mortality and morbidity and therefore it could be applied routinely without the fear of increased complication rate.

Effects of two different crystalloid cardioplegic solutions assessed by myocardial pH, tissue lactate content and energy metabolism

OBJECTIVE

The influence of composition of crystalloid cardioplegia is imprecise in clinical practice. Therefore, we investigated changes in intramyocardial pH, tissue lactate content and energy metabolism during cardioplegic arrest with 2 different crystalloid cardioplegic solutions.

METHODS

Twenty patients were randomly allocated to 2 groups: 10 patients had crystalloid cardioplegia buffered with bicarbonate (neutral pH of 7.8 at 20 degrees) with no additives (St Thomas' II solution) and 10 patients had a non buffered crystalloid cardioplegia (mildly acidic pH of 7.4 at 20 degrees) enriched with glutamate and mannitol (Menasché's solution). Tissue lactate and energy metabolism were measured on myocardial biopsy specimens and intramyocardial pH were continuously measured during cardioplegic arrest by a miniature glass electrode.

RESULTS

There were no statistical differences in hemodynamic results and in AMP, ADP, ATP, lactate values measured on biopsy specimens. The curves of intramyocardial pH were very similar in the 2 groups, the median values were 7.42 +/- 0.1 in group 1 and 7.41 +/- 0.1 in group 2 (temperature corrected values) and the areas under the curves were 260 +/- 4 and 259 +/- 4 in groups 1 and 2 respectively (P = NS).

CONCLUSIONS

Glutamate provided no additive metabolic myocardial protection, bicarbonate had a weak buffering capacity in cold cardioplegic solutions and the 2 studied crystalloid solutions warranted a good myocardial protection in clinical practice.

Meconium ileus and intestinal atresia in fetuses and neonates

A collaborative study was performed to determine the different types and mechanisms of intestinal abnormalities during gestation. Cases had to fulfill one or more of the following three criteria: (1) meconium ileus, (2) intestinal stenosis or atresia, and (3) meconium peritonitis. Esophageal atresia, anorectal atresia, and abdominal wall defects were excluded. One hundred two cases were reviewed from the autopsies of 42 induced abortions, 22 stillborns, and the surgical findings in 38 neonates. Meconium ileus was detected mainly during the second trimester (28/38), and was associated with cystic fibrosis (15), fetal blood deglutition (4), infection (6), or multiple-abnormalities (10), in which three chromosomal aberrations were found. Intestinal stenosis or atresia was more commonly detected during the third trimester of gestation (46/56). Sixteen of the 30 duodenal malformations were associated with trisomy 21, whereas in the 26 small intestinal atresias, signs of distress or ischemia were most frequently detected. Only 8 of 25 meconium peritonitis cases were isolated. A total of 20 cystic fibrosis cases could be proved. In this series, functional abnormalities were observed predominantly in the second trimester and associated mainly with cystic fibrosis or amniotic fluid abnormalities. Anatomic lesions were commonly detected later on and associated with ischemic conditions, chromosomal aberrations, and even cystic fibrosis.

Determination of reliable histological features associated with early triploidy using DNA image cytometry

In order to determine reliable histological features characterizing triploidy, the following features were examined and graded by three pathologists on 46 early abortion specimens: hydropic swelling of the villi, cisterns, villous scalloping, trophoblastic hyperplasia with syncytial vacuolization, single cytotrophoblastic cells in villous stroma, trophoblastic inclusions, microcalcifications and fibrosis. At the same time, the DNA content of the 46 specimens was quantified cytophotometrically using the CAS 200 image analyzer, in order to confirm or not the diagnosis of triploidy. Triploidy was confirmed in 45.7%, and in the triploid group, the grading of three features differed significantly from the non triploid group i.e. cisterns (p < 0.001), trophoblastic hyperplasia (p < 0.05) and trophoblastic inclusions (p < 0.05). Using these three features we were able to give a triploid score per slide which represents the sum of the grades of each of these three features. The minimum score obtained was 0, the maximum was 6. The average of these scores in the triploid group was 3.095, and 1.45 in the non triploid group (p < 0.001). This scoring method on the three significant features (cisterns, trophoblastic hyperplasia and trophoblastic inclusions) appears to be useful to classify an abortion specimen as triploid or not, and to select the specimens for which a DNA quantification may be necessary.

Thiazolidinediones and fatty acids convert myogenic cells into adipose-like cells

Fatty acids and thiazolidinediones act as potent activators of the adipose differentiation program in established preadipose cell lines. In this report, the effects of these agents on the differentiation pathway of myoblasts have been investigated. Exposure of C2C12N myoblasts (a subclone of the C2C12 cell line) to thiazolidinediones or fatty acids prevents the expression of myogenin, alpha-actin, and creatine kinase, thus abolishing the formation of multinucleated myotubes. These treatments lead in parallel to the expression of a typical adipose differentiation program including acquisition of adipocyte morphology and activation of adipose-related genes. A similar transition toward the adipose differentiation pathway also occurs in mouse muscle satellite cells maintained in primary culture. Thiazolidinediones exert their adipogenic effects only in non-terminally differentiated myoblasts; myotubes are insensitive to the compounds. Continuous exposure to inducers after growth arrest is not required to maintain the adipose phenotype, but proliferation of adipose-like C2C12N cells leads to a complete reversion toward undifferentiated cells able to undergo either myogenic or adipogenic differentiation depending on the composition of culture medium. These results indicate that adipogenic inducers, such as thiazolidinediones or fatty acids, specifically convert the differentiation pathway of myoblasts into that of adipoblasts.

In situ microdialysis of prostaglandins in adipose tissue: stimulation of prostacyclin release by angiotensin II

In order to clarify the physiological roles that PGE2 and PGI2, the two major metabolites of arachidonic acid in adipose tissue could play in vivo, their measurements have been undertaken in the interstitial fluid of rat periepididymal adipose tissue using in situ microdialysis. This technique appears suitable with a rather high dialysis yield (70%) for the measurement of prostaglandins. The basal equilibrium extracellular concentrations of 6-keto-PGF1 alpha (the stable metabolite of PGI2) and PGE2 can be estimated to 1 and 0.3 nM, respectively. Experiments designed to study the hormonal regulation of in situ PGI2 and PGE2 production show that (i) lipolysis induced by local perfusion of 10(-6) M isoproterenol is not accompanied by an increase of either 6-keto-PGF1 alpha or PGE2 in the dialysate but, in contrast (ii) perfusion of angiotensin II (10(-7)-10(-5) M) leads, independently of triacylglycerol hydrolysis, to a transient dose-dependent and indomethacin-sensitive increase of released 6-keto-PGF1 alpha with no change in released PGE2. Therefore, in vivo PGI2 appears as the major hormonally regulated prostaglandin in rat adipose tissue, and angiotensin II appears as a physiological effector of its extracellular release.

Glandular-like morphogenesis and secretory activity of human tracheal gland cells in a three-dimensional collagen gel matrix

The extracellular matrix has been demonstrated to affect the differentiation of epithelial cells. We present evidence that in a three-dimensional (3-D) type I collagen gel matrix, isolated human adult tracheal gland (HTG) cells are capable of reconstructing new functional gland-like tubules in vitro. During the first two weeks in culture, HTG cells developed globular epithelial cell aggregates in which lumina is absent. By the third week in culture, the tubulogenesis and the formation of branching structures became evident with a polarized morphology, which in many aspects resembles the in vivo morphology. A central lumen was lined by polarized secretory epithelial cells exhibiting well-developed microvilli and apical secretory granules. Furthermore, we showed that the capacity of in vitro tracheal gland differentiation was associated with the basal deposition of laminin and type IV collagen around the gland-like tubules. A cell-associated 72 kDa type IV collagenase was expressed in developing tubule cells, as shown by immunocytochemistry. The secretion of the antileucoprotease (ALP), a protein marker of tracheal gland serous cells, was bidirectional in gland-like tubules, since up to 65% of released ALP was in the basolateral direction. Taken together, these observations indicate that isolated HTG cells in a 3-D collagen matrix form functional tracheal gland-like tubules and suggest that similar new tracheobronchial gland formations may occur during the human normal gland development and remodeling.

Evidence for a common mechanism of action for fatty acids and thiazolidinedione antidiabetic agents on gene expression in preadipose cells

In diabetic rodents, thiazolidinediones are able to improve insulin sensitivity of target tissues and to reverse, at least partially, the diabetic state. The effects of these drugs on phenotypic expression in various tissues, including adipose tissue, have been reported. We report here that a new thiazolidinedione compound, BRL 49653, exerts, in preadipose cells, potent effects on the expression of genes encoding proteins involved in fatty acid metabolism. These effects of BRL 49653 in Ob 1771 preadipose cells are similar, in terms of kinetics, reversibility, specificity of genes affected, and requirement for protein synthesis, to those already described for natural or nonmetabolizable fatty acids. Moreover, when used at submaximally effective concentrations, BRL49653 and 2-bromopalmitate act in an additive manner to induce gene expression in preadipose cells, but this additivity of effects is lost when one of the compounds is used at a maximally effective concentration. These observations, suggesting similar mechanisms of action for thiazolidinediones and fatty acids, are strongly supported by the demonstration that (i) both molecules activate, in a heterogolous trans-activation assay, the same nuclear receptor of the steroid/thyroid hormone nuclear receptor superfamily and (ii) transfection of 3T3-C2 fibroblasts with an expression vector for this nuclear receptor confers thiazolidinedione inducibility of adipocyte lipid-binding protein gene expression.

Proliferation and differentiation of rat adipose precursor cells in chemically defined medium: differential action of anti-adipogenic agents

Primary rat adipose precursor cells, maintained in the minimal chemically defined medium (ITT medium) able to promote differentiation, have been used to investigate the ability of several agents to modulate their proliferation and their differentiation. Fetuin and fibroblast growth factor (FGF), which exhibited a strong and a weak mitogenic activity, respectively, do not significantly affect the proportion of differentiated cells as indicated by glycerol-3-phosphate dehydrogenase (GPDH) activity values. In contrast, carbaprostacyclin (cPGI2), a stable analogue of prostacyclin, behaves as a true adipogenic factor leading to a 4 to 5-fold increase in GPDH-specific activities with no significant effect on cell growth. Submaxillary gland kallikrein (SMGK), transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) behave as growth-promoting agents but at the same time elicit a dose-dependent inhibition of differentiation. Epidermal growth factor (EGF) and prostaglandin F2 alpha (PGF2 alpha) do not show any effect on cell proliferation at concentrations which exert a maximal inhibitory action on differentiation. Upon removal of EGF from the culture medium, complete resumption of differentiation occurs, whereas upon removal of PGF2 alpha or SMGK, complete resumption only takes place when differentiation is triggered by cPGI2. Upon removal of TNF-alpha, a partial resumption of differentiation is observed, whereas no subsequent differentiation is observed upon TGF-beta removal. These results emphasize the adipogenic, nonmitogenic role of cPGI2 and also allow the distinction between the various adipogenic/mitogenic factors which affect adipose cell differentiation.

Gene transfer to human fetal pulmonary tissue developed in immunodeficient SCID mice

Human fetal lung rudiments (8-12 weeks of development) undergo considerable growth upon microsurgical ectopic implantation in the xenograft-tolerant SCID mouse, and differentiate into a lung-like tissue that includes: (i) bronchial structures lined with pseudostratified, secretory, ciliated epithelium surrounded by smooth muscle and cartilage rings, (ii) submucosal glands, and (iii) alveolar sacs. Normal expression of the cystic fibrosis transmembrane conductance regulator (CFTR) protein was detected by immunostaining in those grafts, and similar differentiation was observed from either normal or cystic fibrosis (CF) fetal lung rudiments. Upon microinjection into human CF or normal lung grafts in SCID mice, beta-galactosidase-adenovirus gene constructs were efficiently transduced into epithelial and glandular cells. Such an in vivo replica of the human respiratory tissue may be a useful experimental model to study normal and pathologic lung development, and to assay candidate therapeutic gene constructs preclinically.

Airway epithelial damage and inflammation in children with recurrent bronchitis

Inflammation and epithelial damage of the bronchial mucosa are frequently identified in children with bronchial diseases. Nevertheless, until now the quantitative assessment of the epithelial damage has never been studied in relation to clinical or respiratory function or mucus abnormalities. Bronchial biopsies and brushings were performed in 31 children with recurrent bronchitis and without atopia. The quantitative histologic data were compared with clinical results, the endoscopic appearance of the mucosa, ciliary beating frequency, mucus transport capacity, leukocyte count, and protein concentration in mucus samples. Most of the biopsies (87%) collected in this group of children without recent acute infections showed extensive epithelial damage. A significant correlation was observed between the degree of shedding and edema (p < 0.01). Bronchial epithelial edema was associated with a significantly decreased (p < 0.01) mucus transport rate. Inflammation of the submucosa was significantly correlated with lymphocyte epithelial infiltration (p < 0.01), total mucus protein content (p < 0.01), and local airway inflammation estimated by bronchoscopy. These results demonstrate that children with recurrent bronchitis develop a severe bronchial inflammation associated with an increased mucus protein content and a reduction in the mucociliary function.

Immunohistochemical localization of cystic fibrosis transmembrane conductance regulator in human fetal airway and digestive mucosa

The cellular distribution of the cystic fibrosis transmembrane conductance regulator (CFTR) in human fetal digestive and respiratory mucosa has been studied by immunohistochemistry. The streptavidin-biotin immunoperoxidase method was applied to paraffin-embedded specimens collected from normal fetuses ranging from 7 to 39 wk of gestation. By the 7th wk, CFTR protein was strongly detected in the yolk sack; in contrast, the staining was weak in the undifferentiated epithelium of the intestine and the airways. At 12 wk, the intestine showed strongly and diffusely stained enterocytes and a basal cytoplasmic reactivity in the first secretory cells. During development, only slight changes could be detected in the digestive epithelial distribution of CFTR. In the airways, the CFTR distribution followed the cephalocaudal maturation. In the tracheal ciliated cells, the CFTR protein was diffusely detected in the cytoplasm as early as 7 wk. After 24-25 wk, CFTR was localized at the apical domain of the ciliated cells and was also present in the collecting ducts and in the glands of the airways, predominantly in the periphery of the acini. Our data suggest that the CFTR is present as early as 7 wk during organogenesis and probably plays an important role during fetal life. There is an evolution in the CFTR distribution during airway development, whereas, in the intestine, CFTR is highly expressed through the epithelium as early as 12 wk and keeps the same distribution until birth.

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.

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.

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.

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.

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.

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.

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.

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.

Nucleolar organizer regions in congenital mesoblastic nephroma

A review of 78 renal tumors in patients under 6 months of age revealed 35 congenital mesoblastic nephromas (CMNs). Based on cellular criteria, 14 were classified as classical, 4 as partly cellular, and 17 as cellular CMN. The mean ages were 24, 11, and 70 days, respectively. There were 13 intrarenal tumors (stage I) but 9 classical, 3 partly cellular, and 5 cellular CMNs extended to the perirenal fat (stage II) and 5 cellular tumors ruptured (stage III). In order to assess cellular proliferative activity, silver staining of nucleolar organizer region (Ag-NOR) proteins was performed on 19 CMNs. The number of Ag-NOR dots per cell was significantly lower in classical and partly cellular CMN than in cellular CMN, whatever the stage (P < .01). Within the cellular CMNs, the mean number of Ag-NOR dots was statistically higher in the single case that recurred with fatal outcome (P < .02). Counting of Ag-NOR dots appears to be a reproducible method for evaluating the biologic potential of CMNs. The number of Ag-NOR dots, DNA content measurements, the histological subclassification, and the presence or absence of tumor at the surgical margins may be useful features in selecting those patients who will benefit from further treatment after nephrectomy.

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.

[Morphogenesis and modifications of the respiratory epithelium]

The tracheobronchial tree begins to form during the fourth week of development through a series of dichotomic divisions of an entoblastic evagination. The morphogenesis and maturation of the respiratory tract depend both on the nature of the extracellular matrix which facilitates cell migration and on epithelial-mesenchymal interactions which induce the proliferation and differentiation of epithelial cells. The study of the plasticity and the phenotypic modifications of secretory cells during both development and inflammatory remodeling of the tracheobronchial mucosa suggests an important role for secretory cells during ciliogenesis and repair.

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.