|
Stargardt's Disease
Stargardt disease is the most common inherited single-gene retinal disease. In terms of the first description of the disease, it follows an autosomal recessive inheritance pattern, which has been later linked to bi-allelic ABCA4 gene variants (STGD1). However, there are Stargardt-like diseases with mimicking phenotypes that are referred to as STGD3 and STGD4, and have a autosomal dominant inheritance due to defects with ELOVL4 or PROM1 genes, respectively. It is characterized by macular degeneration that begins in childhood, adolescence or adulthood, resulting in progressive loss of vision. Signs and symptoms The presentation usually occurs in childhood or adolescence, though there is no upper age limit for presentation and late-onset is possible. The main symptom is loss of visual acuity, uncorrectable with glasses. This manifests as the lack of the ability to see fine details when reading or viewing distant objects. Symptoms typically develop before age 20 (median age of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Coherence Tomography
Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or other scattering media. It uses interferometry techniques to detect the amplitude and time-of-flight of reflected light. OCT uses transverse sample scanning of the light beam to obtain two- and three-dimensional images. Short-coherence-length light can be obtained using a superluminescent diode (SLD) with a broad spectral bandwidth or a broadly tunable laser with narrow linewidth. The first demonstration of OCT imaging (in vitro) was published by a team from MIT and Harvard Medical School in a 1991 article in the journal ''Science (journal), Science''. The article introduced the term "OCT" to credit its derivation from optical coherence-domain reflectometry, in which the axial resolution is based on temporal coherence. The first demonstrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological properties, and its behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code (its genotype) and the influence of environmental factors. Both factors may interact, further affecting the phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and again in his 1982 book '' The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as caddisfly larva cases and beaver dams ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autofluorescence
Autofluorescence is the natural fluorescence of biological structures such as mitochondria and lysosomes, in contrast to fluorescence originating from artificially added fluorescent markers (fluorophores). The most commonly observed autofluorescencing molecules are NADPH and flavin group, flavins; the extracellular matrix can also contribute to autofluorescence because of the intrinsic properties of collagen and elastin. Generally, proteins containing an increased amount of the amino acids tryptophan, tyrosine, and phenylalanine show some degree of autofluorescence. Autofluorescence also occurs in non-biological materials found in many papers and textiles. Autofluorescence from U.S. paper money has been demonstrated as a means for discerning counterfeit currency from authentic currency. Microscopy Autofluorescence can be problematic in fluorescence microscopy. Light-emitting staining, stains (such as fluorescently labelled antibody, antibodies) are applied to Sample (material ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scanning Laser Ophthalmoscopy
Scanning laser ophthalmoscopy (SLO) is a method of examination of the eye. It uses the technique of confocal laser scanning microscopy for diagnostic imaging of the retina or cornea of the human eye. As a method used to image the retina with a high degree of spatial sensitivity, it is helpful in the diagnosis of glaucoma, macular degeneration, and other retinal disorders. It has further been combined with adaptive optics technology to provide sharper images of the retina."Roorda Lab" — (last accessed: 9 December 2006) Published on October 25, 2006—(last accessed: 9 December 2006) Scanning laser ophthalmoscopy SLO utilizes horizontal and vertical scanning mirrors to scan a specific region of ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Long Chain Fatty Acid
A very-long-chain fatty acid (VLCFA) is a fatty acid with 22 or more carbons. Their biosynthesis occurs in the endoplasmic reticulum. VLCFA's can represent up to a few percent of the total fatty acid content of a cell. Unlike most fatty acids, VLCFAs are too long to be metabolized in the mitochondria, in the endoplasmic reticulum (ER) in plants and must be metabolized in peroxisomes. Certain peroxisomal disorders, such as adrenoleukodystrophy and Zellweger syndrome, can be associated with an accumulation of VLCFAs. Enzymes that produce VLCFAs are the targets of herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...s including pyroxasulfone. Major VLCFAs Some of the more common saturated VLCFAs: lignoceric acid (C24), cerotic acid (C26), montanic acid (C28), melissic ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystrophy
Dystrophy is the degeneration of tissue, due to disease or malnutrition, most likely due to heredity. Types * Muscular dystrophy ** Duchenne muscular dystrophy ** Becker's muscular dystrophy ** Myotonic dystrophy * Reflex neurovascular dystrophy * Retinal dystrophy * Cone dystrophy * Corneal dystrophy * Lipodystrophy * Nail dystrophy See also * Muscle weakness * Muscle atrophy * Myotonia * List of biological development disorders The following is a list of terms used to describe biological disorders of development, arranged by root word and shared prefix: References Bibliography * {{DEFAULTSORT:Biological development disorders Lists of diseases Disability-relate ... {{Authority control Medical terminology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal Pigmented Epithelium
The pigmented layer of retina or retinal pigment epithelium (RPE) is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells. History The RPE was known in the 18th and 19th centuries as the pigmentum nigrum, referring to the observation that the RPE is dark (black in many animals, brown in humans); and as the tapetum nigrum, referring to the observation that in animals with a tapetum lucidum, in the region of the tapetum lucidum the RPE is not pigmented. Anatomy The RPE is composed of a single layer of hexagonal cells that are densely packed with pigment granules. When viewed from the outer surface, these cells are smooth and hexagonal in shape. When seen in section, each cell consists of an outer non-pigmented part containing a large oval nucleus and an inner pigmented portion which extends as a series of straight thread-like processes between the rods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipofuscin
Lipofuscin is the name given to fine yellow-brown pigment Granule (cell biology), granules composed of lipid-containing residues of Lysosome, lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells. Formation and turnover Lipofuscin appears to be the product of the oxidation of unsaturated fatty acids and may be symptomatic of membrane damage, or damage to mitochondria and lysosomes. Aside from a large lipid content, lipofuscin is known to contain sugars and metals, including mercury (element), mercury, aluminium, iron, copper and zinc.Chris Gaugler,Lipofuscin", ''Stanislaus Journal of Biochemical Reviews'' May 1997 Lipofuscin is also accepted as consisting of oxidized proteins (30–70%) as well as lipids (20–50%). It is a type of lipochrome and is specifically arranged around the nucleus. The accumulation of lipofuscin-like material may be the result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Phototransduction
Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells ( rods and cones) in the vertebrate retina. A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve. Overview Light enters the eye, passes through the optical media, then the inner neural layers of the retina before finally reaching the photoreceptor cells in the outer layer of the retina. The light may be absorbed by a chromophore bound to an opsin, which photoisomerizes the chromophore, initiating both the visual cycle, which "resets" the chromophore, and the phototransduction cascade, which transmits the visual signal to the brain. The cascade begins with graded polarisation (an analog signal) of the excited photoreceptor cell, as its membrane potential increases from a resting po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP-binding Cassette Transporter
The ABC transporters, ATP synthase (ATP)-binding cassette transporters are a transport system superfamily that is one of the largest and possibly one of the oldest gene family, gene families. It is represented in all extant taxon, extant Phylum, phyla, from prokaryotes to humans. ABC transporters belong to translocases. ABC transporters often consist of multiple subunits, one or two of which are transmembrane proteins and one or two of which are membrane-associated AAA proteins, AAA ATPases. The ATPase subunits utilize the energy of adenosine triphosphate (ATP) binding and hydrolysis to provide the energy needed for the translocation of substrates across membranes, either for uptake or for export of the substrate. Most of the uptake systems also have an extracytoplasmic receptor, a solute binding protein. Some homologous ATPases function in non-transport-related processes such as RNA translation, translation of RNA and DNA repair. ABC transporters are considered to be an ABC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Missense
In genetics, a missense mutation is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid. It is a type of nonsynonymous substitution. Missense mutations change amino acids, which in turn alter proteins and may alter a protein's function or structure. These mutations may arise spontaneously from mutagens like UV radiation, tobacco smoke, an error in DNA replication, and other factors. Screening for missense mutations can be done by sequencing the genome of an organism and comparing the sequence to a reference genome to analyze for differences. Missense mutations can be repaired by the cell when there are errors in DNA replication by using mechanisms such as DNA proofreading and mismatch repair. They can also be repaired by using genetic engineering technologies or pharmaceuticals. Some notable examples of human diseases caused by missense mutations are Rett syndrome, cystic fibrosis, and sickle-cell disease. Impact on Protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominance (genetics)
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second is called recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
