[Chest diseases in elderly: role of imaging and clinical features]. / Pathologie pulmonaire du sujet âgé: rôle de l'imagerie et aspects cliniques.

Chest x-ray is the most useful examination in the elderly as community acquired pneumonia is very frequent in this high risk population. Technical details have to be considered due to the clinical status of elderly patients. Raising arms above the head may help in the radiographic diagnosis of pneumonia. Guidelines for good radiological practice indicate that a chest x-ray should be done in patients with acute respiratory illness and dementia. Clinical and biological findings of pneumonia may be misleading in the elderly and treatment should be instituted rapidly to avoid complications. Lung cancer of elderly patients has to be investigated and treated without consideration for age. Surgery should be done whenever the tumor is removable by lobectomy. Chemotherapy may be safe even in patients older than 80 with an acceptable quality of life.

The BTB/POZ domain of the regulatory proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) interacts with the novel Drosophila TAF(II) factor BIP2/dTAF(II)155.

The BTB/POZ domain is an evolutionarily conserved protein-protein interaction domain present in the N-terminal region of numerous transcription factors involved in development, chromatin remodeling, and human cancers. This domain is involved in homomeric and heteromeric associations with other BTB/POZ domains. The Drosophila BTB/POZ proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) are developmentally regulated transcription factors which are involved in pattern formation along the proximo-distal axis of the leg and antenna, in the morphogenesis of the adult ovaries, and in the control of sexually dimorphic characters. We have identified partners of the BAB1 protein by using the two-hybrid system. The characterization of one of these proteins, called BIP2 for BAB Interacting Protein 2, is presented. BIP2 is a novel Drosophila TATA-box Protein Associated Factor (TAF(II)), also named dTAF(II)155. We show that the BTB/POZ domains of BAB1 and BAB2 are sufficient to mediate a direct interaction with BIP2/dTAF(II)155. This provides a direct link between these BTB/POZ transcription factors and the basal transcriptional machinery. We discuss the implications of the interaction between a BTB/POZ domain and a TAF(II) for the molecular mechanisms of transcriptional control mediated by BTB/POZ transcription factors.

The TFIID components human TAF(II)140 and Drosophila BIP2 (TAF(II)155) are novel metazoan homologues of yeast TAF(II)47 containing a histone fold and a PHD finger.

The RNA polymerase II transcription factor TFIID comprises the TATA binding protein (TBP) and a set of TBP-associated factors (TAF(II)s). TFIID has been extensively characterized for yeast, Drosophila, and humans, demonstrating a high degree of conservation of both the amino acid sequences of the constituent TAF(II)s and overall molecular organization. In recent years, it has been assumed that all the metazoan TAF(II)s have been identified, yet no metazoan homologues of yeast TAF(II)47 (yTAF(II)47) and yTAF(II)65 are known. Both of these yTAF(II)s contain a histone fold domain (HFD) which selectively heterodimerizes with that of yTAF(II)25. We have cloned a novel mouse protein, TAF(II)140, containing an HFD and a plant homeodomain (PHD) finger, which we demonstrated by immunoprecipitation to be a mammalian TFIID component. TAF(II)140 shows extensive sequence similarity to Drosophila BIP2 (dBIP2) (dTAF(II)155), which we also show to be a component of Drosophila TFIID. These proteins are metazoan homologues of yTAF(II)47 as their HFDs selectively heterodimerize with dTAF(II)24 and human TAF(II)30, metazoan homologues of yTAF(II)25. We further show that yTAF(II)65 shares two domains with the Drosophila Prodos protein, a recently described potential dTAF(II). These conserved domains are critical for yTAF(II)65 function in vivo. Our results therefore identify metazoan homologues of yTAF(II)47 and yTAF(II)65.

Toucan protein is essential for the assembly of syncytial mitotic spindles in Drosophila melanogaster.

The toc gene of Drosophila melanogaster encodes a 235-kD polypeptide with a coiled-coil domain, which is highly expressed during oogenesis (Grammont et al., 1997, 2000). We now report the localization of the Toucan protein during early embryonic development. The Toucan protein is present only during the syncytial stages and is associated with the nuclear envelope and the cytoskeletal structures of the syncytial embryo. In anaphase A, Toucan is concentrated at the spindle poles near the minus end of microtubules. This microtubule association is very dynamic during the nuclear cell cycle. Mutant embryos lacking the Toucan protein are blocked in a metaphase-like state. They display abnormal and nonfunctional spindles, characterized by broad poles, detachment of the centrosomes, and failure of migration of the chromosomes. These results strongly suggest that Toucan represents a factor essential for the assembly and the function of the syncytial mitotic spindles.

Expression and cellular localization of the Toucan protein during Drosophila oogenesis.

The toucan (toc) gene is required in the germline for somatic cell patterning during Drosophila oogenesis. To better understand the function of toc, we performed a detailed analysis of the distribution of the Toucan protein during oogenesis. Toc expression is restricted to the germline cells and shows a dynamic distribution pattern throughout follicle development. Mislocalization of the Toc protein in mutant follicles in which the microtubule network is altered indicates that microtubules play a role in Toc localization during oogenesis.

The Drosophila toucan (toc) gene is required in germline cells for the somatic cell patterning during oogenesis.

We have characterized a new gene, called toucan, that is expressed and required in germline cells to promote proper differentiation of the somatic follicle cells. toucan mutant ovaries are defective in (i) the enclosure of newly formed germline cysts by the follicle cells, (ii) the formation of interfollicular stalks, (iii) the migration of the follicle cells over the oocyte and (iv) the formation of the eggshell. Overexpression of a toucan cDNA in the germline leads to the production of longer interfollicular stalks than wild-type ovaries, a phenotype that is the exact opposite of the toucan mutant phenotype. This observation shows that the formation of the interfollicular stalks depends not only on interactions among the somatic cells but also requires a germline signal. Moreover, dominant interactions have been observed between toucan and certain alleles of the daughterless, Notch and Delta genes, each of which is required in the somatic cells for the formation of egg chambers. toucan encodes for a large protein with a coiled-coil domain but has no other homology with known proteins. We propose that toucan participates in the production or localization of a germline-specific signal(s) that is required for the patterning of the follicular epithelium.

[Efficacy and tolerability of a combination of indomethacin and gentamicin for preventing inflammation after cataract surgery]. / Efficacité et tolérance d'une association d'indométacine et de gentamicine dans la prévention de l'inflammation consécutive à la chirurgie de la cataracte.

PURPOSE: The aim of the study was to compare 2 combinations of anti-inflammatory drug and antibiotic, in patients undergoing cataract surgery: 0.1% indomethacin/gentamicin or 0.1% dexamethasone/ neomycin. METHODS: Two hundred and two patients undergoing extra-capsular cataract extraction with posterior chamber lens implantation were included in a randomized, double-blinded multicentric study comparing 2 parallel groups of treatment. Treatment was administered the day before surgery, the day of surgery and for the following 7 days. On the 8th post-operative day, the antibiotic was stopped and the anti-inflammatory treatment continued alone until the 30th post-operative day. Post-operative ocular inflammation was assessed clinically on the 1st, 7th, 15th and 30th post-operative days. The main evaluation criterion of treatment efficacy was the assessment of anterior chamber flare and cells. RESULTS: No statistically significant difference-was observed between the 2 treatment groups concerning post-operative inflammation. Both treatments were well tolerated. CONCLUSION: Eye drops combining 0.1% indomethacin and gentamicin proved to be effective and well tolerated in preventing inflammation after cataract surgery.

Drosophila ovary morphogenesis: analysis of terminal filament formation and identification of a gene required for this process.

The adult ovary of Drosophila is composed of approximately 20 parallel repetitive structures called ovarioles. At the anterior tip of each ovariole is a stack of 8-9 disc-shaped cells, called the terminal filament. Ovariole morphogenesis starts with the formation of the terminal filaments. Using two enhancer trap markers for terminal filament cells, we show that terminal filaments form in a progressive manner from medial to lateral across the ovary and that the number of terminal filament cells in a developing stack increases gradually. This process occurs during the second half of the third larval instar. One of these enhancer trap mutations, which is in the bric à brac gene, demonstrates that this gene is necessary for terminal filament formation and that a terminal filament cell cluster is required for ovariole morphogenesis to take place.

The BTB domain of bric à brac mediates dimerization in vitro.

The gene bric à brac (bab) is required for the proper development of the limbs and ovary in Drosophila melanogaster. bab encodes a BTB domain (also called a POZ domain), an approximately 115-amino-acid conserved motif found primarily in the N termini of zinc finger proteins. In this paper, we show that the BTB domain of bab can mediate protein dimerization in vitro. In addition, we demonstrate that the first 51 amino acids of the bab BTB domain are sufficient for dimerization, and we identify amino acids within this region that are required for binding.

The BTB domain, found primarily in zinc finger proteins, defines an evolutionarily conserved family that includes several developmentally regulated genes in Drosophila.

The Drosophila bric à brac protein and the transcriptional regulators encoded by tramtrack and Broad-Complex contain a highly conserved domain of approximately 115 amino acids, which we have called the BTB domain. We have identified six additional Drosophila genes that encode this domain. Five of these genes are developmentally regulated, and one of them appears to be functionally related to bric à brac. The BTB domain defines a gene family with an estimated 40 members in Drosophila. This domain is found primarily at the N terminus of zinc finger proteins and is evolutionarily conserved from Drosophila to mammals.

[Acanthamoeba keratitis. Apropos of 2 cases]. / Kératites à acanthamoeba. A propos de deux observations.

Acanthamoeba keratitis is a rare pathology which is currently observed with increasing frequency in France. Two new cases are reported in young patients wearing soft hydrophile contact lenses. One patient apparently followed cleansing instructions, but the other did not. The essential parasitological diagnosis was confirmed rapidly after comeal sampling, but had been highly suspected from the clinical symptomatology. Treatment combining propamidine and eye-drop antibiotics led to recovery in both cases. Anatomical damage was however observed in one case and a penetrating graft was necessary.

Pattern formation in the limbs of Drosophila: bric à brac is expressed in both a gradient and a wave-like pattern and is required for specification and proper segmentation of the tarsus.

We have identified the gene bric à brac and show that it is required for pattern formation along the proximal-distal axis of the leg and antenna of Drosophila. In bric à brac mutant legs, the bristle pattern of the three central tarsal segments is transformed towards the pattern of the most proximal tarsal segment. In addition, bric à brac mutant legs and antennae have segmentation defects. bric à brac encodes a nuclear protein that shares a highly conserved domain with two transcription factors from Drosophila. bric à brac function is dosage dependent and is required in a graded manner for the specification of tarsal segments. The graded requirement for bric à brac correlates with its graded expression pattern, suggesting that the concentration of BRIC A BRAC protein specifies segment identity in the tarsus.

Intronic and 5' flanking sequences of the Drosophila beta 3 tubulin gene are essential to confer ecdysone responsiveness.

The expression of the beta 3 tubulin gene is regulated, at the transcriptional level, by the steroid hormone ecdysone, in Drosophila Kc cells. Using a transient expression assay, we show that 360 bp from the first intron of the beta 3 tubulin gene, associated with the 5' flanking sequences, are essential to confer ecdysone inducibility on a minimum promoter driving the chloramphenicol acetyl transferase (CAT) gene. The 5' flanking region contains ecdysone-independent cis-positive elements located in proximity to the promoter. Deletion analysis of the 360 bp intronic region reveals that a fragment of 57 bp is crucial for the ecdysone response of the beta 3 tubulin gene. This fragment contains 5'-TGA(A/C)C-3' motifs homologous to ecdysone responsive elements (EcRE) half sites. Band shift assays show that this 57-bp fragment is bound by three specific complexes. One of them appears to be involved in the level of the ecdysone response.

Enhancer and silencer elements within the first intron mediate the transcriptional regulation of the beta 3 tubulin gene by 20-hydroxyecdysone in Drosophila Kc cells.

We have studied the transcriptional regulation of the beta 3 tubulin gene by the steroid hormone 20-hydroxyecdysone (20-E) in Drosophila Kc cells. A series of hybrid genes, with different fragments of the beta 3 tubulin gene driving the bacterial chloramphenicol acetyl transferase (CAT) gene were constructed. The promoter activity was assayed after transient expression in Kc cells, in the presence and the absence of 20-E. Constructs with 0.91 kb upstream from the transcription start site and 360 bp from the first large intron allowed the hormonal regulation, i.e. a repression in the absence of 20-E and a derepression-activation in the presence of the hormone. This 360 bp fragment contains several enhancers and silencer(s) sequences. The regulation of the expression of the beta 3 tubulin gene results from the combined activity of all the positive and negative regulatory sequences of the first intron, and a dialogue with the promoter sequences. The nucleotide sequence of this intronic regulatory-fragment has been established and we have identified several EcRE (ecdysone responsive element) consensus sequences.

In Drosophila Kc cells 20-OHE induction of the 60C beta3 tubulin gene expression is a primary transcriptional event.

In Drosophila Kc cells, the 60C beta3 tubulin transcription unit, whose expression is induced by 20-hydroxyecdysone (20-OHE), has the same structure as in Drosophila. This gene is characterized by an unusual 5' intron of regulating importance, by an alternatively spliced second intron and by a long 3' transcribed but untranslated region. This gene codes for two beta3 tubulin isoforms with one amino acid difference. We have established that beta3 tubulin gene expression is transcriptionally regulated by the steroid hormone in a time and hormonal concentration-dependent fashion, without requirement of protein synthesis. This implies that this transcriptional induction is a primary event and that this gene is probably a direct target for the 20-OHE receptor.

Regulatory elements in the first intron contribute to transcriptional regulation of the beta 3 tubulin gene by 20-hydroxyecdysone in Drosophila Kc cells.

We have studied the transcriptional regulation of the beta 3 tubulin gene by the steroid hormone 20-hydroxyecdysone (20-OH-E) in Drosophila Kc cells. A series of hybrid genes with varying tubulin gene lengths driving the bacterial chloramphenicol acetyl transferase (CAT) gene were constructed. The promoter activity was assayed after transient expression in Kc cells, in the presence or absence of 20-OH-E. We find that 0.91Kb upstream from the transcription start site contain one or several hormone independent positive cis-acting elements, responsible for the constitutive expression of the beta 3 tubulin gene. In the large (4.5 Kb) first intron of this gene, we identified additional hormone dependent negative and positive regulatory elements, which can act in both directions and in a position-independence manner. Then, the negative intron element(s), which repress the transcription in the absence of 20-OH-E has characteristics of silencer.

20-OH-ecdysone regulates 60 C beta tubulin gene expression in Kc cells and during Drosophila development.

Cultured Kc cells of Drosophila melanogaster are sensitive to the insect moulting hormone, 20-hydroxy-ecdysone (20-OH-E). Morphological changes of Kc-treated cells were observed and electron microscopic analysis of pseudopodia shows a large increase in the number of microtubules, all arranged in the same orientation. The 60 C beta tubulin gene which is expressed only in 20-OH-E-treated cells encodes a 2.6-kb mRNA which is essentially cytoplasmic and polyadenylated. The corresponding premessenger is 7 kb in length and is absent in untreated cells. Two peaks of expression of the 60 C beta tubulin gene are observed during Drosophila development: at midembryogenesis (stage 8-13 h) and at the late third instar larvae-early pupae stage. By use of the Ecdysone 1 mutant, 60 C beta tubulin gene expression was demonstrated to be regulated in part by 20-OH-E during Drosophila development. Through these two complementary biological models of study, the mode and role of beta tubulin gene regulation are discussed.