Search results for "Endocrinology"
showing 10 items of 8907 documents
Specific, concentration-dependent uptake of vitellin by the oocytes ofNereis virens (Annelida, Polychaeta) in vitro
1991
One purpose of this study was the development of methods for radioactive labeling and handling of the yolk protein of Nereis virens, another, the utilization of this tracer in nereid oocyte cultures to describe the kinetics and specificity of yolk protein uptake. Accumulation of labeled yolk protein by growing oocytes is linear over time, specific for yolk protein, and dependent on tracer concentration in the medium. Incorporation of yolk protein follows saturation kinetics which allows us to reproducibly determine the characteristics of this process. The apparent KM of ∼ 1 × 10−8 M indicates the high affinity of the transport system; the Vmax (160–400 pg protein/day × oocyte) reveals that …
Chapter 23: Choline, a precursor of acetylcholine and phospholipids in the brain
1993
Publisher Summary The plasma level of free choline is remarkably constant at about 10 pM in animals and human. Ingestion of food, especially when rich in choline or lecithin, transiently elevates the plasma choline level up to 20 pM or more. In contrast, choline-deficient diet leads to a reduction of the plasma level by about 50%. Choline is considered an essential nutrient, which is predominantly supplied as phosphatidylcholine (lecithin). For a long time, neuroscientists have been intrigued by the fact that choline is a precursor for the biosynthesis of both acetylcholine (ACh) and phospholipids. For 50 years, lecithin has been marketed in Europe as a drug that was claimed to prevent exha…
Antiphosphatidylserine Antibodies Affect Rat Yolk Sacs in Culture: a Mechanism for Fetal Loss in Antiphospholipid Syndrome
2004
PROBLEM: A variety of reproductive impairments have been reported in the context of the antiphospholipid syndrome (APS). APS is associated with the presence of antibodies to negatively charged phospholipids that may affect the outcome of pregnancy. METHOD OF STUDY: Rat embryos were cultured within their yolk sacs. The effects of two antiphosphatidylserine monoclonal aPS antibodies (HL5B, RR7F) regarding their influence on growth and apoptotic events of the yolk sacs, as well as on growth and the morphology of the embryos, were studied. RESULTS: Exposure of rat embryos and their yolk sacs to aPS inhibited yolk sac growth. Moreover, increased number of apoptotic events of giant cells in the a…
Identification of the yolk receptor protein in oocytes of Nereis virens (Annelida, Polychaeta) and comparison with the locust vitellogenin receptor
1992
In oviparous animals large amounts of yolk proteins of extraovarian origin are accumulated by developing oocytes during vitellogenesis. The yolk protein precursors, the vitellogenins (VTG), are transported into the oocytes by receptor-mediated endocytosis. In oocytes of the polychaetous annelid, Nereis virens, the receptor protein for VTG was visualized by ligand blotting studies as a protein with an apparent molecular mass of 190 kDa under non-reducing conditions. Anti-Locusta VTG receptor antibodies recognize the Nereis VTG receptor protein. The Nereis VTG receptor protein binds Locusta and Schistocerca VTG; the VTG receptor proteins of both locust species bind the Nereis vitellin. These …
The effects of experimentally manipulated yolk androgens on growth and immune function of male and female nestling collared flycatchers Ficedula albi…
2009
Hormone-mediated maternal effects may be an important mechanism for adjusting offspring phenotype to particular requirements of the environment. We manipulated the levels of testosterone and androstenedione in the yolk of collared flycatcher Ficedula albicollis eggs to investigate the effects of pre-natal exposure to androgens on growth and immune function. Androgen treatment tended to reduce the growth of males, and enhance the growth of females, as indicated by significant interaction between sex and androgen treatment. Cellular immune function was not affected by androgen treatment or sex. Survival of nestlings until fledging was not related to androgen treatment. Our results indicate th…
Elevated intraocular pressure induces neuron-specific β-III-tubulin expression in non-neuronal vascular cells.
2019
Purpose Pathological alterations within optic nerve axons and progressive loss of the parental retinal ganglion cell (RGC) bodies are characteristics of glaucomatous neuropathy. Abnormally elevated intraocular pressure (IOP) is thought to be the major risk factor for most forms of glaucomatous changes, while lowering of the IOP is the mainstream of treatment. However, the pathophysiological mechanisms involved in neurodegenerative changes are poorly understood. It remains still a matter of debate whether elevated IOP harms the neurons directly or indirectly through alterations in the retinal vascularization. Methods We analysed morphological and molecular changes within the retina exposed t…
The LDL receptor in the retina: the missing link in aging, the new target in dietary prevention
2012
National audience; Purpose: The discovery of the LDL receptor (LDLR) in 1985 by Brown and Goldstein was awarded by a Nobel Prize. The LDLR has initially been identified for its role in mediating the endocytosis of LDL particles in the vascular endothelium. The deposition of lipids, including cholesterol and cholesteryl esters in Bruch’s Membrane in the one hand, and in the vessel intima in the other hand, is one of the common features of age related macular degeneration (AMD) and cardiovascular disease (CVD). Dietary habits with high intakes of omega 3 long chain fatty acids (LCFA) have been associated with AMD prevention. Similar effects have been demonstrated in CVD prevention. The mechan…
Phosphodiesterase10A: abundance and circadian regulation in the retina and photoreceptor of the rat.
2011
Phosphodiesterase10A (PDE10A) is a dual specific cyclic nucleotide phosphodiesterase that is specifically enriched in striatum and which has gained attention as a therapeutic target for psychiatric disorders. The present study shows that PDE10A is also highly expressed in retinal neurons including photoreceptors. The levels of PDE10A transcript and protein display daily rhythms which could be seen in preparations of the whole retina. Corresponding changes in PDE10A mRNA were seen in photoreceptors isolated using laser microdissection. This suggests that the expressional control of the photoreceptor Pde10a gene contributes to the observed cyclicity in the amount of retinal PDE10A. The daily …
Fructose diet induced short-term impairment of cone sensitivity and gene expression in rat retina
2012
National audience; Abstract: Purpose A high fructose diet has been widely used to trigger insulin resistance in rodent; insulin resistance is one of the major risk factor for the development of type 2 diabetes. Thirty to 40% of diabetic patients develop diabetic retinopathy. In this study, we aimed to evaluate the short-term effect, at 1, 3, 5, 8 days, of a 60% fructose diet, on photoreceptor sensitivity and gene expression in the retina of Brown Norway rats. Methods: Flicker electroretinograms (8Hz) were recorded under anesthesia, from both eyes simultaneously in order to study sensitivity of photoreceptors. Then, rats were euthanized and enucleated. Retinae and posterior poles were collec…
Combined effects of aging and a pro-diabetic diet on retinal function in a murine model of aging of the human eye
2009
; Purpose: Improvement of life expectancy and changes in the dietary behaviour of developed populations are accompanied with the prevalence of diabetes and age-related ocular pathologies. Aging of the retina is characterized by accumulation of lipids at the basement of the retinal pigment epithelium - Bruch’s membrane complex.Meanwhile increased oxidative stress is one of the features of aging and diabetes. A fructose-rich diet induces insulin resistance and hypertriglyceridemia, mimicking diabetes. The goal of our study was to evaluate the effects of a pro-diabetic fructose-enriched diet on the retinal function of the ApoB100,LDLR-/- mice, a murine model of aging of the human eye. Methods…