Differential expression of the neuronal acetylcholine receptor alpha 2 subunit gene during chick brain development.

In situ hybridization histochemistry reveals localized expression of the nicotinic acetylcholine receptor (nAChR) alpha 2 subunit mRNA restricted to the lateral spiriform nucleus (SpL) of the chick diencephalon. The alpha 2 nAChR transcripts are not detected in immature SpL neurons at 4.5-5 days of embryonic development. They begin to accumulate in the SpL at embryonic day 11 and increase until the newborn stage. Specific alpha 2 cDNA amplification by the polymerase chain reaction shows that during this period, the absolute content of alpha 2 mRNA increases about 20-fold. The expression of the alpha 2 nAChR gene is thus developmentally regulated and appears concomitant with the entry of cholinergic fibers into the SpL, as demonstrated by choline acetyltransferase immunohistochemistry.

A 5'-flanking region of the chicken acetylcholine receptor alpha-subunit gene confers tissue specificity and developmental control of expression in transfected cells.

The 5' end and promoter region of the alpha-subunit gene of chicken muscle acetylcholine receptor was mapped and sequenced. It includes a TATA and a CAAT box and a potential Sp1-binding site. When inserted in front of the chloramphenicol acetyltransferase gene, this promoter (including 850 base pairs of upstream sequence) directed high transient chloramphenicol acetyltransferase expression in transfected mouse C2.7 myotubes but not in C2.7 myoblasts or nonmyogenic 3T6 cells.

A radioimmunoassay of human leukocyte interferon using protein A-containing Staphylococcus aureus.

We report the establishment of a radioimmune assay for human alpha-interferon using highly purified alpha-interferon labeled with iodine-125, a purified rabbit immunoglobulin directed against human interferon and the Cowan strain of Staphylococcus aureus. Radiolabeling conditions used do not change the antigenicity of interferon molecules. The regression of counts bound upon log. dose was found to be linear down to 10 units/ml of alpha-interferon (6-7 X10-12 M). This assay was specific for alpha-interferons derived from human peripheral blood leukocytes and from a continuous line of lymphoblastoid cells. No cross-reaction was found with either human beta-interferon or murine interferon. Neither human serum nor plasma interfered with the assay. Correlation between biological assay and radioimmune assay was found to be significant.

Actin and myosin multigene families: their expression during the formation and maturation of striated muscle.

The initial formation of skeletal muscle fibers is accompanied by the expression of muscle-type actin and myosin genes. During subsequent maturation of muscle fibers in vivo, developmental changes in the fetal/adult isoforms of these proteins occur. Skeletal muscle-specific transcripts coding for different myosin heavy chains accumulate sequentially both in vivo and in vitro. A genetic analysis demonstrates that these genes are clustered, implicating cis-acting regulatory factors. In contrast, actin and myosin light chain genes are dispersed in the mouse genome. These gene families show a different developmental "strategy": Genes expressed in adult cardiac tissue are coexpressed with the corresponding skeletal muscle sequence during fetal development. This phenomenon also occurs in adult tissue. Under conditions of cardiac overload, adult rat hearts accumulate skeletal actin mRNA and cardiac actin transcripts. In some mouse lines, a mutant cardiac actin gene locus is present. The presence of a second active upstream promoter at this locus depresses transcription of the bone fide gene, resulting in low levels of mature cardiac actin mRNA. In this situation skeletal actin gene transcripts accumulate. Genes expressed in the same fetal or adult muscle phenotype are not linked, suggesting that their coexpression is regulated by transacting factors. The promoter regions of such genes in the mouse have no common characteristics of primary structure with the exception of an E1A-type enhancer core sequence, which has a conserved 5' flanking element, seen for actin and myosin light chain genes. Reintroduction of these promoter regions into muscle cells provides a functional test for such potential regulatory sequences.

[Infectious crystalline keratopathy: a case report]. / Kératopathie cristalline infectieuse: à propos d'une observation.

We report a case of perforated infectious crystalline keratopathy in a 88-year-old woman. Corneal surgery like keratoplasty and topical corticosteroids are the main causative factors present in the rare reported cases. Clinically, the anterior layers of cornea exhibit slowly progressive stellate infiltrates. "Viridans streptococci" are the most common micro-organisms involved but their culture for identification is difficult. As compared to cultures, histologic examination is more sensitive for diagnosis, by showing clusters of bacteria in the corneal stroma with no inflammatory response.

[Dural fistula between the middle meningeal artery and cavernous sinus discovered in ophthalmology]. / Fistule durale entre artère méningée moyenne et sinus caverneux, de découverte ophtalmologique.

The authors report case of a dural arterio-venous fistula fed exclusively by the external carotid artery.

[Macular functions in professional divers]. / Fonction maculaire chez le plongeur professionnel.

PURPOSE: Air diving is frequently practiced by professionals or sportsmen. Controversial data exist in the literature on the existence of retinal abnormalities in divers. PATIENTS AND METHODS: 18 divers (aged: 27-58y) who dived around 2000 times in their life were studied: half of them dived only with air while the others used an O2-enriched gas mixture (40 to 60%). None of them had presented a bend (decompression sickness). Visual acuity and ocular fundus examination have been explored. A quantification of color vision and central visual field, so as a fluorescein angiography have been performed. RESULTS: No alteration of visual acuity was noted; abnormalities in the color vision and the visual field are reported; however the angiographic lesions described in the literature have not been observed. DISCUSSION: The alterations of color vision were quite severe but not very frequent. No correlation was found with any characteristics or type of diving. CONCLUSION: These observations are comforting for sportive divers who do not dive very often nor very deep but an individual predisposition is suspected.

Regulation of skeletal muscle stem cell behavior by Pax3 and Pax7.

Pax genes have important roles in the regulation of stem cell behavior, leading to tissue differentiation. In the case of skeletal muscle, Pax3 and Pax7 perform this function both during development and on regeneration in the adult. The myogenic determination gene Myf5 is directly activated by Pax3, leading to the formation of skeletal muscle. Fgfr4 is also a direct Pax3 target and Sprouty1, which encodes an intracellular inhibitor of fibroblast growth factor (FGF) signaling, is under Pax3 control. Orchestration of FGF signaling, through Fgfr4/Sprouty1, modulates the entry of cells into the myogenic program, thus controling the balance between stem cell self-renewal and tissue differentiation. This and other aspects of Pax3/7 function in regulating the behavior of skeletal muscle stem cells are discussed.

[Multifocal ERG using ERG-jet and Gold Foil electrodes in normal subjects: comparison and reproducibility]. / ERG multifocal avec électrodes ERG-jet et Gold Foil chez le sujet normal: comparaison et reproductibilité.

PURPOSE: To compare multifocal electroretinogram (mfERG) amplitudes with the Gold Foil electrode and ERG-jet electrode. To study mfERG amplitude changes between two successive records (intraindividual reproducibility). METHODS: The right eye of 27 normal subjects was examined. Two mfERG recordings using the 61-hexagon strategy (Vision Monitor, Métrovision, France) were made with both ERG-jet and Gold Foil electrodes. N1 and P1 wave amplitudes were analyzed in the central response and in four concentric rings. Bland and Altman analysis was used for the reproducibility study. RESULTS: MfERG amplitudes were significantly lower with the Gold Foil electrode, which averaged 72+/-10% of ERG-jet amplitudes. For N1 and P1 waves, the percentage change for the intraindividual reproducibility study was 9.1% and 6.7%, respectively, with the ERG-jet electrode and 18.2% and 13.5%, respectively, with the Gold Foil electrode. CONCLUSION: MfERG amplitudes were larger and more reproducible with an ERG-jet electrode than with a Gold Foil electrode. The limits of agreement of each ring can be used in clinical practice to determine whether the variation between two mfERG recordings over time is normal, which could reflect a retinal disorder.

[Improved visualization of fundus with green-light ophthalmoscopy]. / Intérêt de l'examen biomicroscopique du fond d'oeil en lumière verte.

Monochromatic light accentuates details of different retinal layers because of its variable absorption and reflectance by structures both within and above these layers. Red-free light is little used, although it is an elementary method. Green-light ophthalmoscopy, with its short wavelength, enhances some fundus and vitreous structures and may make the examination of pathologic conditions (premacular pathology, vascular abnormalities, etc.) easier. Furthermore, it is often more comfortable for the patient.

Structure and polymorphism of the mouse myelin/oligodendrocyte glycoprotein gene.

We have isolated and characterized genomic clones containing the mouse myelin/oligodendrocyte glycoprotein (MOG) gene. It spans a region of 12.5 kb and consists of eight exons. Its exon-intron structure differs from that of classical MHC-class I genes, with which it is linked in the mouse genome. Nucleotide sequencing of the 5' flanking region reveals that it contains several putative protein-binding sites, some of them in common with other myelin gene promoters. One intragenic polymorphism has been identified: it consists of a GA repeat, defining at least three alleles in mouse inbred strains, and is easily detectable using the polymerase chain reaction method.

[Cornea and anterior chamber implant with flexible closed haptics]. / Cornée et implant de chambre antérieure à anses flexibles fermées.

Authors report the result of 148 cases of flexible (with closed haptics) anterior chamber lens implantation. Analysis of per and post-operative corneal complications, Study shows increase in time of such complications, in relation to secondary displacement and alteration of lens shape.

["Bell clappers" with "ophthalmologic alarm". Apropos of 2 cases of colloid cysts of the 3d ventricle]. / "Battants de cloche" à "alarme ophtalmologique". A propos de deux cas de kyste colloïde du 3e ventricule.

We report two cases of third ventricle colloid cyst in atypical adult's neurological descriptions, tracked down by ophthalmologist, proved by computed tomography and magnetic resonance imaging. We describe physio-pathological mechanism and dwell on different ophthalmological events of exceptional occurrence with those benign tumours and on ophthalmological investigation's importance in case of persisting and unexplained headache. We conclude with spontaneous clinical course, and neurological surgery's efficacy on hydrocephalus.

A comparison between mammalian and avian fast skeletal muscle alkali myosin light chain genes: regulatory implications.

A single locus in the mouse, rat and chicken encodes both alkali myosin light chains, MLC1F and MLC3F. This gene has two distinct promoters and gives rise to two different primary transcripts, which are processed by alternative and different modes of splicing to form MLC1F and MLC3F mRNAs. The MLC1F/MLC3F gene is very similar between mouse, rat and chicken, in terms of its overall structure, the length and location of the introns, and the splice site consensus sequences. Nucleotide sequences of coding regions are very conserved but 3' and 5' non coding regions of the mRNAs have diverged. In the MLC1F promoter regions, several blocks of nucleotides are highly conserved (more than 70% homology), especially a sequence of about 70 nucleotides, located between positions -80 and -150 relative to the Cap site. Conserved blocks of homology are also found in the MLC3F promoter regions, although the common sequences are shorter. The presence of such highly conserved nucleotide sequences in the 5' flanking regions suggests that these sequences are functionally important in initiation of transcription and regulation of expression of this complex gene. Primer extension experiments indicate multiple cap sites for MLC3F mRNA.

Functional activity of the two promoters of the myosin alkali light chain gene in primary muscle cell cultures: comparison with other muscle gene promoters and other culture systems.

Proximal upstream flanking sequences of the mouse myosin alkali light chain gene encoding MLC1F and MLC3F, the mouse alpha-cardiac actin gene and the chicken gene for the alpha-subunit of the acetylcholine receptor were linked to the bacterial chloramphenicol acetyl transferase (CAT) gene and transfected into primary cultures derived from mouse skeletal muscle or into myogenic cell lines. We demonstrate that the mouse MLC1F/MLC3F gene has two functional promoters. In primary muscle cultures, a 1200 bp sequence flanking exon 1 (MLC1F) and a 438 bp sequence flanking exon 2 (MLC3F) direct CAT activity in myotubes, but not in myoblasts or in non myogenic 3T6 and CV1 cells. Developmentally regulated expression is also seen with the alpha-cardiac actin (320 bp) and acetylcholine receptor alpha-subunit (850 bp) upstream sequences in the primary culture system. Transfection experiments with myogenic cell lines show different results with a given promoter construct, reflecting possible differences in the levels of regulatory factors between lines. Different muscle gene promoters behave differently in a given cell line, suggesting different regulatory factor requirements between these promoters.