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Biomedical subjects

C Remé

Publications and source records attributed to C Remé.

At least 37 records · Page 2Linked to original sources
PubMed1985

[Circadian rhythm, the retina and light].

The renewal systems in visual cells, disk-shedding and autophagy, exhibit endogenous circadian rhythms, primarily controlled by an ocular oscillator. Many characteristics of these rhythms have been elucidated, but the actual site and nature of the ocular clock are still unknown. Conceivable regulators of the rhythm are the neurohormone melatonin and the putative retinal neurotransmitter dopamine. Furthermore, dopamine might regulate the sensitivity of the retina to light. It is shown that disk-shedding and autophagy have a circadian sensitivity to light input. The magnitude of the light response was greatest at the beginning of the subjective night, i.e., 12 hours out of phase with the endogenous peak. The latency of the light response was shortest at the beginning of the subjective day, when the endogenous rhythms are at their peak. Additionally, the response to drugs known to modify the metabolism of dopamine was analyzed. The light response of both disk-shedding and autophagy were inhibited by the drugs in the subjective night and stimulated in the subjective day. Thus, light as well as drugs can influence the renewal processes in visual cells.

Animals↗
PubMed1984

The shift of Schlemm's canal during the remodelling of the chamber angle in the developing rat eye.

A morphometric analysis of the pre- and postnatal development of the tissue components of the chamber angle was performed in the rat. One eye of each of five weight-matched littermates was evaluated by light microscopy at the following time points: prenatal days 18, 21; day 0 (= day of birth); postnatal days 5, 10, 15, 20, 40, 60. Composite photomicrographs of the entire chamber angle area at a magnification of 5776 X were prepared from each eye under investigation. Developmental stages were analysed by direct measurements between selected anatomical reference points and by computerised calculations that were obtained from geometrical constructions on the photomicrographs. A statistical analysis was performed on the correlation of measurements and calculations with the entire investigated time period. This way, a modification of the allometric growth analysis was developed. Our data indicate that Schlemm's canal undergoes a distinct forward shift from a position next to the peripheral retina towards the chamber angle recess. This forward shift is paralleled by a considerable growth of the ciliary body. In contrast, an arrest of growth of tissues between the end of Descemet's membrane and the anterior end of Schlemm's canal is observed. Thus, with the anterior chamber angle components remaining constant and the posterior ones growing in the meridional diameter, a forward and internal shift of Schlemm's canal results.

Animals↗
PubMed1984

Chronic clorgyline dampens rat retinal rhythms.

In the rat retina, the rhythm of disk-shedding from visual cell outer segments is circadian in nature, whereas autophagic degradation of organelles in inner segments follows a circadian rhythm that persist in constant light but not in constant darkness. The monoamineoxidase inhibitor clorgyline can phase delay circadian rhythms in hamster and rat. However, clorgyline does not phase delay the plasma corticosterone rhythm nor does it delay the phase position of the retinal disk-shedding rhythm in a light-dark cycle or in constant darkness: only the amplitude of the circadian rhythm is reduced. A marked reduction in rhythm amplitude is also found in the number of autophagic vacuoles after chronic clorgyline treatment. Thus the circadian rhythm of disk-shedding appears to be primarily driven by an oscillator within the eye, and clorgyline modulates the light response of retinal parameters but not their timing.

Animals↗
PubMed1984

Circadian rhythm in rat retinal dopamine.

Rat retinal dopamine concentration and synthetic rate exhibit a circadian rhythm that persists in the absence of time cues. Although the population of retinal amacrine cells containing dopamine is small, retinal dopamine neurones may lie on the pathway mediating light information to the circadian system.

Animals↗
PubMed1984

Modification of autophagic degradation by medium- and illumination conditions in frog visual cells in vitro.

In vertebrate visual cells, cytoplasmic organelles are degraded within autophagic vacuoles occurring in inner segments. In isolated frog retinas in vitro, an increase of autophagic activity as compared to in vivo controls was observed and a reduction of autophagic activity in dim red light as compared to bright white light (Remé, 1981). In this study, isolated frog retinas were superfused: (a) with and without serum addition to the superfusion medium at 400 1 X illumination; (b) without serum at 400 1 X fluorescent light or without visible light. Autophagy was significantly decreased, in cones more than in rods, in retinas superfused with serum containing medium and superfused without visible light. The increased autophagy in serum free medium is interpreted to provide precursor molecules for protein synthesis. The reduction of autophagy in darkness may reflect different functional and metabolic states of visual cells.

Animals↗
PubMed1984

[Retinal light damage--summary of experimental and clinical observations].

The article presents a comprehensive review of the literature on light damage to the retina with special reference to clinical aspects. A definition of the different modes of action of light on the retina and a brief summary of current theories on possible mechanisms of light-damage are presented. Experimental studies applying ophthalmological light sources to the primate eye are described as well as investigations on photochemical light-damage to the human eye. Possible implications of these observations for some types of retinal degeneration are discussed. Finally, the importance of considering possible light-hazards in clinical routine is emphasized.

Animals↗
PubMed1983

The occurrence of cell death during the remodelling of the chamber angle recess in the developing rat eye.

Prenatal and postnatal stages of the developing chamber angle in the rat eye were analysed qualitatively by light and electron microscopy. One eye of each of five weight-matched littermates was investigated at the following time points: prenatal days 14, 17, 18 and 21; day 0 = day of birth; postnatal days 5, 10, 15, 20, 40, 60, 100 and 200. From postnatal days 5 to 60, conspicuous amounts of necrotic cells were observed within the chamber angle area. At birth and at postnatal day 200, only a few scattered necroses were observed. Necrotic cells were found within the trabecular area, the region of Fontana's spaces and beams and the peripheral iris, the iris root, the ciliary body and the adjoining choroid. Large macrophages containing lysosomal dense bodies were found within the previously described areas and were frequently in close contact with necrotic cells. It is concluded that cell death within the developing chamber angle of the rat may represent an important event that may contribute to two morphogenetic effects: (1) the opening of large spaces of Fontana and (2) space formation within the trabecular area and uveoscleral outflow routes.

Animals↗
PubMed1983

The development of the chamber angle in the rat eye. Morphological characteristics of developmental stages.

The pre- and postnatal development of the chamber angle region was studied in the rat. The eyes of five weight-matched littermates were investigated by light- and electron microscopy at each of the following times: prenatal days 14, 17, 18, 21; day of birth; postnatal days 5, 10, 15, 20, 40, 60, 100, 200. Major developmental stages are demonstrated and the morphological characteristics of each stage shown. Developmental periods in the rat are correlated with periods that have previously been outlined in the human (Remé and Lalive 1981). Major periods comprise the following events: I. anlage formation (day 17 prenatal - day postnatal); II. differentiation into definitive structures (days 5-10); III. specialization of definitive structures (days 10-20); IV. final components (days 20-60); V. final molding and rarefaction (days 60-100). Our data indicate that the developing rat eye is a suitable experimental model for studies on the development of the chamber angle. Moreover, this study provides baseline data for a separate investigation on morphogenetic events contributing to the remodeling processes occurring within the vertebrate chamber angle.

Animals↗
PubMed1981

Periods of development of the normal human chamber angle.

Stages of fetal and postnatal development of the normal human chamber angle are reevaluated. Major growth phases can be detected: trabecular anlage formation (around the 15th week), differentiation into definitive structures (around the 24th week), specialisation of the definitive structures (around the 28th week), achievement of final components (birth) and final moulding of the chamber angle and the maturation of its cellular and extracellular constituents (1-8 years). A cleavage or gradual atrophy of chamber angle tissues could not be detected during any of the above phases, nor was a membrane found, which covered the chamber angle recess at any stage of development. In the light of the described periods, potential disturbances of development are discussed, which might be a cause of congenital glaucoma.

Anterior Chamber↗
PubMed1980

[Histopathological aspects of the surgical treatment of congenital glaucoma].

Two tissue specimens obtained by trabeculectomy from infant eyes with different reactive changes in their chamber angles due to previous trabeculotomies are described and discussed. Both eyes had been operated on glaucoma for several times. In the first case, the trabeculotomy had resulted in the formation of laminar scar tissue with hyalinized and atrophic trabecular sheets. In the second case, however, the original trabecular meshwork was completely transformed to a fibrocellular scar tissue. These different structural changes in the chamber angle region may support the hypothesis that such tissue reactions are not only the result of the antiglaucoma procedure adopted, but are also caused by surgical wounds.

Female↗
PubMed1977

[Some aspects of congenital glaucoma (author's transl)].

The following paper on certain aspects of congenital glaucoma was read at a meeting for advanced medical education. Particular emphasis was placed on a review of the theories and concepts dealing with pathogenetic factors of congenital glaucoma. Two main concepts appeared to be most prominent in past and current literature: 1. The concept of a membrane obstructing the chamber angle, 2. underdevelopment or malformation of all or some structure of the chamber angle region. In order to clarify the above mentioned concepts, three stages of development of normal human chamber angles were demonstrated by light and electronmicroscopy. Aspects of surgical treatment of congenital glaucoma were discussed. Light and electronmicroscopic findings in some trabeculectomy specimens were shown. In eyes which underwent repeated surgery, marked scar tissue was seen in the area of trabecular meshwork, thus obliterating aqueous pathways. In those cases, an excision of trabecular tissue (trabeculectomy) was recommended rather than destruction of remaining trabecular tissue (trabeculotomy).

Cornea↗
PubMed1976

[Clinical and morphological studies in a case of congenital glaucoma combined with an ocular-dental-digital dysplasia (author's transl)].

Clinical and morphological studies were undertaken to characterize a case of congenital glaucoma combined with an ocular-dental-digital dysplasia in a two year old patient. Light and electromicroscopic investigations of a surgically removed trabecular specimen were carried out. A trabeculotomy had been performed at this exact site 10 months prior to removal. The existence of a canal of Schlemm was demonstrated. The regular trabecular meshwork and trabecular region was replaced by fairly dense scar tissue, containing rudimentary intertrabecular spaces. Proliferating corneal endothelial cells covered the wound area up to the uveal part of the trabecular region. The morphological findings correlated well with the clinical observation of continued raised intraocular pressure despite trabeculotomy. It is concluded that, contrary to the situation in adult onset glaucoma, the strong proliferative tendency of juvenile tissue has a marked influence on the postoperative efficacy of the trabeculotomy.

Child, Preschool↗