Surface-sensitive diamond photonic crystals for high-performance gas detection

Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching a 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultrahigh sensitivity to the surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed, and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing.

Cross-talk between Msx/Dlx homeobox genes and vitamin D during tooth mineralization

Rickets is associated with site-specific disorders of enamel and dentin formation, which may reflect the impact of vitamin D on a morphogenetic pathway. This study is devoted to potential cross-talk between vitamin D and Msx/Dlx transcription factors. We raised the question of a potential link between tooth defects seen in mice with rickets and Msx2 gene misexpression, using mutant mice lacking the nuclear vitamin D receptor as an animal model. Our data showed a modulation of Msx2 expression. In order to search for a functional impact of this Msx2 misexpression secondary to rickets, we focused our attention on osteocalcin as a target gene for both vitamin D and Msx2. Combining Msx2 overexpression and vitamin D addition in vitro, we showed an inhibitory effect on osteocalcin expression in immortalized MO6-G3 odontoblasts. Finally, in the same cells, such combinations appeared to modulate VDR expression outlining the existence of complex cross-regulations between vitamin D and Msx/Dix pathways.

Msx1 homeogene antisense mRNA in mouse dental and bone cells

Msx1 plays a key role in early dental and cranio-facial patterning. A systematic screening of Msx1 transcripts during late postnatal stages of development evidenced not only sense mRNA but also antisense mRNA in the skeleton. Natural antisenses are able to bind their corresponding sense RNAs and block protein expression. Specific reverse-transcription polymerase chain reaction (RT-PCR) Northern-blotting using riboprobes and primer extension analysis allowed to identify and sequence a mouse 2184-base Msx1 antisense transcript. The transcription start site was located in a region including a consensus TATA box. In situ hybridization evidenced an increase in antisense mRNA expression during dental and bone cell differentiation in prenatal (Theiler stages E15.5-18.5) and newborn mice. This upregulation was related to Msx1 protein downregulation in cells expressing Msx1 sense mRNA. In vitro, transient Msx1 sense and antisense mRNA overexpression was performed in MO6-G3 cells, which pertain to the odontoblast lineage (polarization and dentin sialoprotein and phosphoprotein synthesis). The balance between antisense and sense Msx1 mRNAs appeared to control Msx1 protein levels. These data suggest that a bidirectional transcription of Msx1 homeogene may control Msx1 protein levels, and therefore may be critical in cell communication and differentiation during dental and cranio-facial development and mineralization.

Substitution of Met-69 by Ala or Gly in TEM-1 beta-lactamase confer an increased susceptibility to clavulanic acid and other inhibitors

In some inhibitor-resistant TEM-derived beta-lactamases, Met-69 is substituted by Leu, Ile or Val. Residue 69 is located in a region of strong structural constraints, at the beginning of H2 alpha-helix, and in the vicinity of B3 and B4 beta-strands. Analysis of the three-dimensional structure of TEM-1 beta-lactamase suggests that alteration of the substrate-binding site can be produced by changes of the size of residue 69 side chain. Met-69 was substituted by alanine or glycine in TEM-Bs beta-lactamase (a TEM-1-related enzyme) using site-directed mutagenesis. The minimum inhibitory concentrations of the mutants compared with the wild-type revealed an increased susceptibility to beta-lactamase inhibitor-beta-lactam combinations and to first-generation cephalosporins. Comparing the Met69Ala and Met69Gly beta-lactamases with TEM-Bs, K(m) constants of the mutants showed an increased affinity for most beta-lactams but the kcat for most substrates did not change substantially. Mutants also demonstrated lower IC50 for the three inhibitors (clavulanic acid, tazobactam and sulbactam). The two substitutions of the residue 69 by alanine and glycine had a noticeable effect on K(m) values of TEM-Bs beta-lactamase, and on affinity for beta-lactamase inhibitors.

Hepatic glucokinase is induced by dietary carbohydrates in rainbow trout, gilthead seabream, and common carp

Glucokinase (GK) plays a central role in glucose homeostasis in mammals. The absence of an inducible GK has been suggested to explain the poor utilization of dietary carbohydrates in rainbow trout. In this context, we analyzed GK expression in three fish species (rainbow trout, gilthead seabream, and common carp) known to differ in regard to their dietary carbohydrate tolerance. Fish were fed for 10 wk with either a diet containing a high level of digestible starch (>20%) or a diet totally deprived of starch. Our data demonstrate an induction of GK gene expression and GK activity by dietary carbohydrates in all three species. These studies strongly suggest that low dietary carbohydrate utilization in rainbow trout is not due to the absence of inducible hepatic GK as previously suggested. Interestingly, we also observed a significantly lower GK expression in common carp (a glucose-tolerant fish) than in rainbow trout and gilthead seabream, which are generally considered as glucose intolerant. These data suggest that other biochemical mechanisms are implicated in the inability of rainbow trout and gilthead seabream to control blood glucose closely.

Molecular cloning, tissue distribution and sequence analysis of complete glucokinase cDNAs from gilthead seabream (Sparus aurata), rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio)

The enzyme glucokinase (GK) (EC 2.7.1.1) plays an important role in the control of glucose homeostasis. Qualitative and/or quantitative variations in GK enzyme have been postulated by previous studies to explain why dietary carbohydrate utilisation is lower in gilthead seabream (Sparus aurata) and rainbow trout (Oncorhynchus mykiss) than in common carp (Cyprinus carpio). In this study, we report the isolation and characterisation of a full-length cDNA coding for GK in these teleosts. Amino acid sequences derived from these cDNA clones are highly similar to other vertebrate GKs. These findings, including a detailed phylogenetic analysis, reveal that GK gene highly homologous to mammalian GK exists in these fish species with similar tissue specific expression (mainly liver).

Estradiol-dependent uterine leiomyomas in transgenic mice

Uterine leiomyomas are a major health problem for women of reproductive age. The molecular biology of these tumors is poorly understood partly because of the lack of relevant animal models. We have produced transgenic mice expressing the simian virus 40 T antigen driven by the promoter of the Calbindin-D9K (CaBP9K) gene and either -1,000 or -117 bp of regulatory sequences so as to establish in vivo, uterine smooth muscle tumor models. Six transgenic mouse lines were obtained. Leiomyomas developed in all of them, with an almost complete penetrance of the phenotype. The smooth muscle tumors arose in different parts of the female reproductive tract. Leiomyomas usually developed in the corpus of the uterus, but one mouse line developed leiomyomas in the horn of the uterus, and another in the vagina. The CaBP9K regulatory sequences directing the expression of the Tag gene possess an estradiol responsive element, and accordingly, development of the tumors was strictly under the control of estrogen. Expression of the Tag gene is not only necessary for the initiation of the tumor but also for its development and maintenance. These transgenic mouse models should be useful for studying the pathobiology of uterine leiomyomas and could be instrumental in designing new therapeutic approaches to this disease.

Functional and growth properties of a myometrial cell line derived from transgenic mice: effects of estradiol and antiestrogens

This study describes the properties of a myometrial cell line, m-M116, that was derived from a leiomyoma developed in an adult female transgenic mouse harboring the simian virus 40 large T antigen (Tag) under the control of the 5'-regulatory sequence of the calbindin D9k (CaBP9k) gene. As the expression of this transgene is governed by the CaBP9k estrogen-responsive element, m-M116 cells were grown in medium supplemented with 17 beta-estradiol. The cells were long lived, had Tag-positive nuclei, and were nontumorigenic when injected into nude mice. They formed irregular layers of elongated cells with typical features of uterine, smooth muscle cells, as assessed by the presence of alpha-smooth muscle actin and desmin filaments, estradiol and progesterone receptors, and expression of the CaBP9k gene. The rate of cell doublings and the expression of the Tag gene in early passaged cells depended on the presence of 17 beta-estradiol. Tamoxifen, a mixed estrogen agonist-antagonist, also stimulated the growth of m-M116 cells, whereas ICI 182 780, a pure antiestrogen, blocked cell growth. Later passages of m-M116 cells still had a smooth muscle phenotype, but proliferated even in the absence of 17 beta-estradiol. These mouse uterine smooth muscle cells obtained by targeted oncogenesis provide a useful model for studies of the progression of steroid-independent carcinomas.

cis-Acting elements and transcription factors involved in the intestinal specific expression of the rat calbindin-D9K gene: binding of the intestine-specific transcription factor Cdx-2 to the TATA box

The calbindin-D9K (CaBP9k) gene is mainly expressed in differentiated duodenal epithelial cells and is used as a model for studying the molecular mechanisms of intestine-specific transcription. The gene has been cloned, two major DNase-I-hypersensitive sites in the duodenum have been described, and a vitamin-D-response element has been identified. We have now analysed the transcription factors and regulatory sequences involved in the transcription of the CaBP9k gene in the intestine in ex vivo and in vitro experiments. Transfection experiments in intestinal (CaCo-2) and non-intestinal (HeLa) cell lines defined two regions in the 5'-flanking sequences of the rat CaBP9k gene. A minimal proximal region (-117 to +20) promoted transcription in both intestinal expressing and non-expressing cell lines. Tissue specificity was conferred by the sequences situated further upstream, which are responsible for complete repression in the non-intestinal cells. Intestinal transcription was specified by the proximal region, containing a specialized TATA box, and a distal region, which contains a previously described intestinal DNase-I-hypersensitive site. In vitro DNase I footprinting, electrophoretic mobility shift assays and antibody supershift assays were used to examine the factors bound to the proximal promoter region (-800 to +80 bp). Rat duodenal nuclear extracts protected 12 sites. Some of them appear to be binding sites for ubiquitous (nuclear factor 1) or hepatic-enriched sites (hepatocyte nuclear factors 1 and 4, enhancer binding protein alpha and beta factors. DNA binding studies and transfection experiments indicated that an intestine-specific transcription factor, caudal homeobox-2, binds to the TATA box of the rat CaBP9k gene. These data contribute to our understanding of the control of the intestinal transcription of the CaBP9k gene and demonstrate that several trans-acting factors, other than the vitamin D receptor, may be factors for intestine-specific CaBP9k gene expression.

Familial acromegaly: a specific clinical entity--further evidence from the genetic study of a three-generation family

Familial acromegaly is a very rare inherited disorder, characterized by the clustering within a single family of several related cases with somatotroph adenomas and acromegaly. The causes of these dominantly inherited pituitary tumours remain unknown. Although these families have a clinical presentation distinct from that of multiple endocrine neoplasia type 1 (MEN-1), the question of this syndrome as being linked to the MEN-1 locus has remained open. Our aim was to study a three-generation family with cases of acromegaly in a mother and her son, to explore better the clinical presentation of the disease, its pattern of inheritance and to test the hypothesis of a genetic linkage to the MEN-1 locus using closely linked polymorphic genetic markers. The refined analysis of 15 unaffected relatives revealed miscellaneous non-specific endocrine dysfunctions and the presence of multiple lipomata, as noted previously in some cases. Moreover, the notion of acromegalo-gigantism in the maternal grandmother and an incomplete penetrance appeared even more typical, suggesting that familial acromegaly is a specific clinical entity. Finally, under the hypotheses assumed for segregation analysis, no clinical, biological or genetic evidence of linkage to the MEN-1 locus could be retained in this family. However, these conclusions were limited because of incomplete penetrance and uncertain definition of the carrier status. Therefore, we conclude that further identification of the genetic predisposition to familial acromegaly might be obtained from the combined molecular genetic analysis of several families presenting with the same clinical features.

Contrasting effects of tamoxifen and ICI 182 780 on estrogen-induced calbindin-D 9k gene expression in the uterus and in primary culture of myometrial cells

Antiestrogens have a large range of tissue- and promoter-specific actions, many of which still remain unclear, particularly in the uterus. Thus, we have analyzed the effects of two antiestrogens, tamoxifen (TAM) and ICI 182 780 (ICI) on the uterine estrogen-responsive gene calbindin-D9k (CaBP9k), in the ovariectomized rat uterus, and in primary cultures of myometrial cells. In the ovariectomized rat uterus, estradiol (E2) or E2 plus TAM induced CaBP9k mRNA to the same levels in 6h. Rats given TAM alone had the same mRNA concentration, but maximal induction was obtained later, 12h after injection. ICI alone did not induce CaBP9k gene expression. Rats given E2 plus ICI had low uterine CaBP9k mRNA levels at 6-12h that became undetectable at 24h. Thus ICI has a full antagonistic effect on E2-induced CaBP9k gene. Estradiol receptor (ER) assays showed that TAM had a partial antagonist effect, while ICI had a full antagonist effect on the ER. We also analyzed the effect of TAM and ICI on CaBP9k gene expression in primary cultures of myometrial cells. The effects were similar to those observed in whole uterus. Thus, TAM has mixed effects, being an agonist for CaBP9k gene induction, and an antagonist for ER. ICI antagonizes the effects of E2 on the CaBP9k gene in myometrial cells and in the intact uterus, but in a way that does not involve a decrease in the cellular content of ER. Instead, it interferes with at least one of the events leading to transcriptional activation.

Identification of DNA sequences that bind retinoid X receptor-1,25(OH)2D3-receptor heterodimers with high affinity

Vitamin D3 receptors (VDR) bind as heterodimers with retinoid X receptors (RXR) to vitamin D response elements (VDRE) and transactivate gene expression in a 1,25(OH)2D3-dependent manner. These elements are tandem direct repeats (DRs) of the hexamer RGGTCA separated by three nucleotides (DR3). We determined whether this DR3 was the optimal and/or only recognition sequence, by PCR-mediated binding site selection with reticulocyte lysate-expressed hVDR and mRXRalpha, and a pool of random sequences. We derived a consensus binding site for RXR-VDR heterodimers, RGGTCANN RRGTTCAB, and analyzed 10 of the 45 sequences slected by EMSA, methylation interference and transfection experiments: all the sequences were specific and acted as positive VDREs; the underlined purine of the spacer interacted with the heterodimer; the mutation of the third T in the second motif to a G did not influence VDRE activity. Thus, the selectivity of vitamin D pathway involving heterodimerization rather than VDR-homodimerization is not due to internal sequence variations. Except for mouse osteopontin VDRE, the natural VDREs would be efficient, only when helped by adjacent sequences and/or transactivators other than VDR and RXR.

Differential expression of the full-length and secreted truncated forms of EGF receptor during formation of dental tissues

The developmental regulation of various receptor forms may be a key-element in the local fine tuning of growth factor effects. The present study focuses on the tissue- and stage-specificity of the alternative splicing of EGF receptor transcripts in the rat incisor. In situ hybridization, as well as light- and electron-microscopic immunolocalization were performed with a set of tools which enable us to discriminate the full-length and secreted truncated forms of EGF receptor. Our data show that, apart from a transient expression in differentiating odontoblasts, EGF receptor expression was predominantly observed in the dental epithelium. In the crown, the expression of the full-length EGF receptor was maximal during preameloblast proliferation and differentiation, decreased in differentiated ameloblasts, and remained low throughout enamel secretion. On the other hand, maturation stage ameloblasts, which regulate the final mineralization of enamel, express high levels of the full-length EGF receptor. In contrast with ameloblasts, epithelial supra-ameloblastic cells, which are not directly involved in the deposition of enamel matrix, showed an alternating predominance of the secreted truncated form during the secretion stage, and the full-length form during the maturation stage. The presence of the secreted truncated EGF receptor form was supported by the electron microscopic detection of extracellular aggregates of immunoreactive EGF receptor. Finally, Northern-blotting of enamel organ samples confirmed the presence of transcripts corresponding to mRNAs of both EGF receptor forms. During root formation, a decreasing gradient of full-length EGF receptor form expression was observed from the apical loop to the disrupting zone in root epithelium. The secreted truncated EGF receptor form was essentially detected in epithelial cells of the disrupting zone of root epithelium. During crown formation, the secreted truncated EGF receptor form, which appears to be synthesized by epithelial supra-ameloblastic cells and secreted toward ameloblasts, may competitively bind EGF receptor ligands and modify activation of the full-length EGF receptor.

Calbindin-D9k gene expression in the uterus: study of the two messenger ribonucleic acid species and analysis of an imperfect estrogen-responsive element

The calbindin D9k (CaBP9k) gene is under strict estrogen control in the rat uterus. This tissue contains two CaBP9k messenger RNA (mRNA) species. We have used primer extension analysis, reverse transcriptase associated with polymerase chain reaction, and RNase H digestion to show that these two mRNA species have the same structural features, including 5'- and 3'-ends, and poly(A) tail length. Our results suggest that the difference in electrophoretic mobilities of the two mRNA species might be due to interaction with another factor. We also analyzed the imperfect estrogen-responsive element (ERE) present on the first 5'-splice site of the rat CaBP9k gene. The oligonucleotide corresponding to the CaBP9k ERE was cloned in the plasmid pBLCAT2 (where the thymidine kinase promoter governs the expression of the chloramphenicol acetyl transferase gene) and transfected into MCF7 cells. This CaBP9k ERE was found to be a hormone-inducible enhancer that worked in an orientation-independent manner on a heterologous promoter and was functional at physiological hormone concentrations. One CaBP9k ERE conferred only weak (about 2-fold) estrogen induction, but two EREs cloned in tandem were strongly synergistic (14- to 16-fold). The CaBP9k ERE also bound to the partially purified estrogen receptor (ER) and to ER expressed in COS cells by gel shift assay. Methylation interference showed that all the guanine residues in both half-sites of the CaBP9k ERE were protected by ER binding. Thus, ER binds to the CaBP9k ERE in a way similar to other EREs. The gel shift assay results indicate that the strong synergistic effect of two EREs cloned in tandem is not due to cooperative binding between the two elements. As the CaBP9k gene is under strong estrogenic control in the uterus in vivo, the imperfect CaBP9k ERE may cooperate with another trans-acting factor to become fully efficient.

Estrogen-induced calbindin-D 9k gene expression in the rat uterus during the estrous cycle: late antagonistic effect of progesterone

Progesterone modulates estrogen-stimulated responses in the uterus. Calbindin-D 9k (CaBP9k), a 17 beta-estradiol-responsive gene expressed in the uterus, was used as a marker to examine the interactions between endogenous progesterone and estradiol in the rat. The variations in uterine CaBP9k messenger RNAs (mRNAs) during the rat estrous cycle indicated that CaBP9k gene expression was greatest during the estrogen-dominated phases (proestrus and estrus) and became totally repressed during diestrus, when progesterone predominates. Estradiol was found to be the major controlling factor of CaBP9k gene expression in vivo, progesterone antagonizing estrogen-induced CaBP9k gene expression. The inhibitory role of progesterone was further examined in two experiments. Mature cyclic rats were injected with the progesterone antagonist RU486 before the progesterone surge of proestrus, and the estrous cycle was mimicked in ovariectomized rats by sequential injections of estrogen and progestin. Progesterone did not appear to be involved in the rapid decrease in CaBP9k mRNA during estrus but was implicated in the down-regulation of the estrogen-stimulated CaBP9k gene expression at the end of estrus and during diestrus. This delayed effect of progesterone was confirmed in the ovariectomized rat model. CaBP9k mRNA accumulation in estrogen-primed ovariectomized rats was suppressed by estrogen followed 1 h later by the progesterone agonist R5020. This effect occurred more than 24 h after progestin treatment. The inhibition of the estrogen-induced CaBP9k gene expression in the rat uterus by progesterone is certainly mediated by the progesterone receptor, because progesterone had no effect without estrogen priming or when the antagonist RU486 was used. The delayed progesterone effect probably does not involve depletion of nuclear estrogen receptors, the major rapid mechanism proposed for estrogen inhibition by progesterone in the rodent uterus, or control of estrogen receptor synthesis, as shown by Northern blot analysis of estrogen receptor mRNA.

[Antibiotic sensitivity testing on the automatic MS-2. Use of antibiotic discs from 3 different sources]

The MS-2 automate for antibiotic susceptibility testing was experimented under conditions different from those recommended by the manufacturer, namely using antibiotic discs from different firms. Susceptibility of eight Enterobacteriaceae strains recovered from urine to nine antibiotics borne by discs from three different firms was tested. Results obtained with the different brands of discs were dissonant in less than 7% of cases (major and minor disagreements compounded). Major discrepancies ranged from 2.8 to 4.2% according to the origin of discs. The reproducibility study found consistent results in 87.5% of cases, and satisfactory results (i.e. minor discrepancies excluded) in 93.5% of cases.

[Serum antibacterial activity during antibiotic treatment in automated bacteriology]

The conventional serum-dilution bactericidal test used for monitoring antibiotic therapy in severely infected in patients requires 72 h. Use of an automaton would be expected to provide faster results. We tested the MS-2 diagnostic automaton which performs kinetic analysis of bacterial growth. A relation between exponential growth onset time and initial bacterial concentration of the inoculum was first determined using successive ratio 10 dilutions. Sixty-two serum samples from twenty-one patients with endocarditis or septicemia were examined. A selection of findings is presented. Results of the automatic method and serum-dilution bactericidal test are studied comparatively. From our data we define the major advantages of automation: only 0.65 ml of serum and 10 minutes are needed to perform the test and results are obtained in five to twelve hours according to the bacterial strain. This new technique could be integrated in the monitoring protocol of severe infections.

[Atypical mycobacteria and mycobacteriosis]

Atypical mycobacteria were isolated from 16 patients admitted to the Versailles Hospital Center over a two-years period (1981-1982). Two cases of pulmonary disease due to M. avium-intracellulare and one case of skin disease due to M. marinum were diagnosed. Pulmonary infection remained doubtful in two patients despite repeated recovery of M. Kansasii and M. chelonei.