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Alkaptonuria
Alkaptonuria is a rare inherited genetic disease which is caused by a mutation in the ''HGD'' gene for the enzyme homogentisate 1,2-dioxygenase (); if a person inherits an abnormal copy from both parents (it is a recessive condition), the body accumulates an intermediate substance called homogentisic acid in the blood and tissues. Homogentisic acid and its oxidized form ''alkapton'' are excreted in the urine, giving it an unusually dark color. The accumulating homogentisic acid causes damage to cartilage (ochronosis, leading to osteoarthritis) and heart valves, as well as precipitating as kidney stones and stones in other organs. Symptoms usually develop in people over 30 years old, although the dark discoloration of the urine is present from birth. Apart from treatment of the complications (such as pain relief and joint replacement for the cartilage damage), the drug nitisinone has been found to suppress homogentisic acid production, and research is ongoing as to whether it can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogentisate 1,2-dioxygenase
Homogentisate 1,2-dioxygenase (homogentisic acid oxidase, homogentisate oxidase, homogentisicase) is an enzyme which catalyzes the conversion of homogentisate to 4-Maleylacetoacetate, 4-maleylacetoacetate. Homogentisate 1,2-dioxygenase or HGD is involved in the catabolism of aromatic rings, more specifically in the breakdown of the amino acids tyrosine and phenylalanine. HGD appears in the metabolic pathway of tyrosine and phenylalanine degradation once the molecule homogentisate is produced. Homogentisate reacts with HGD to produce maleylacetoacetate, which then is further used in the metabolic pathway. HGD requires the use of Fe2+ and O2 in order to cleave the aromatic ring of homogentisate. Image:Homogentisic acid.svg, homogentisate Image:4-maleylacetoacetic acid.svg, 4-Maleylacetoacetate, 4-maleylacetoacetate Enzyme active site The active site of Homogentisate 1,2-dioxygenase was determined through the crystal structure, which was captured through the work of Titus et al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitisinone
Nitisinone, sold under the brand name Orfadin among others, is a medication used to slow the effects of hereditary tyrosinemia type 1 (HT-1). Uses Nitisinone is used to treat hereditary tyrosinemia type 1 (HT-1) in patients from all ages, in combination with dietary restriction of tyrosine and phenylalanine. Since its first use for this indication in 1991, it has replaced liver transplantation as the first-line treatment for this ultra rare condition. Adverse effects The most common adverse reactions (>1%) for nitisinone are elevated tyrosine levels, thrombocytopenia, leukopenia, conjunctivitis, corneal opacity, keratitis, photophobia, eye pain, blepharitis, cataracts, granulocytopenia, epistaxis, pruritus, exfoliative dermatitis, dry skin, maculopapular rash and alopecia.has several negative side effects; these include but are not limited to: bloated abdomen, dark urine, abdominal pain, feeling of tiredness or weakness, headache, light-colored stools, loss of appetite, weight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the world. The most common symptoms are joint pain and stiffness. Usually the symptoms progress slowly over years. Initially they may occur only after exercise but can become constant over time. Other symptoms may include joint swelling, decreased range of motion, and, when the back is affected, weakness or numbness of the arms and legs. The most commonly involved joints are the two near the ends of the fingers and the joint at the base of the thumbs; the knee and hip joints; and the joints of the neck and lower back. Joints on one side of the body are often more affected than those on the other. The symptoms can interfere with work and normal daily activities. Unlike some other types of arthritis, only the joints, not internal organs, are af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kidney Stone
Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine stream. A small stone may pass without causing symptoms. If a stone grows to more than , it can cause blockage of the ureter, resulting in sharp and severe pain in the lower back or abdomen. A stone may also result in blood in the urine, vomiting, or painful urination. About half of people who have had a kidney stone will have another within ten years. Most stones form by a combination of genetics and environmental factors. Risk factors include high urine calcium levels, obesity, certain foods, some medications, calcium supplements, hyperparathyroidism, gout and not drinking enough fluids. Stones form in the kidney when minerals in urine are at high concentration. The diagnosis is usually based on symptoms, urine testing, and medical i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ochronosis
Ochronosis is a syndrome caused by the accumulation of homogentisic acid in connective tissues. The condition was named after the yellowish (ocher-like) discoloration of the tissue seen on microscopic examination. Macroscopically, though, the affected tissues appear bluish-grey because of a light-scattering phenomenon known as the Tyndall effect. The condition is most often associated with alkaptonuria, but can occur from exogenous administration of phenol complex (chemistry), complexes such as hydroquinone. It was first described by Rudolf Virchow in 1865.Findlay GH, et al. Ochronosis. Clinics in Dermatology 1989;7:28-35 Types The two types of ochronosis are endogenous and exogenous. The endogenous variety is an autosomal-recessive disease, known as alkaptonuria, that is caused by a lack of homogentisate oxidase enzyme.Charlín, R., Barcaui, C. B., Kac, B. K., Soares, D. B., Rabello-Fonseca, R. and Azulay-Abulafia, L. (2008), Hydroquinone-induced exogenous ochronosis: a report ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Limbus
The corneal limbus (''Latin'': corneal border) is the border between the cornea and the sclera (the white of the eye). It contains stem cells in its palisades of Vogt. It may be affected by cancer or by aniridia (a developmental problem), among other issues. Structure The corneal limbus is the border between the cornea and the sclera. It is highly vascularised. Its stratified squamous epithelium is continuous with the epithelium covering the cornea. The corneal limbus contains radially-oriented fibrovascular ridges known as the palisades of Vogt that contain stem cells. The palisades of Vogt are more common in the superior and inferior quadrants around the eye. Clinical significance Cancer The corneal limbus is a common site for the occurrence of corneal epithelial neoplasm. Aniridia Aniridia, a developmental anomaly of the iris, disrupts the normal barrier of the cornea to the conjunctival epithelial cells at the limbus. Glaucoma The corneal limbus may be c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone Mineral Density
Bone density, or bone mineral density, is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. The measurement is painless and non-invasive and involves low radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip. The forearm may be scanned if the hip and lumbar spine are not accessible. There is a statistical association between poor bone density and higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone Fracture
A bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a ''comminuted fracture''. A bone fracture may be the result of high force impact or stress, or a minimal trauma injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, osteopenia, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture. Signs and symptoms Although bone tissue contains no pain receptors, a bone fracture is painful for several reasons: * Breaking in the continuity of the periosteum, with or without similar discontinuity in endosteum, as both contain multiple pain receptors. * Edema and hematoma of nearby soft tissues caused by ruptured bone marrow evokes pressure pain. * Involuntary muscle spasms trying to hold bone fragments in place. D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valvular Heart Disease
Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging,Burden of valvular heart diseases: a population-based study. Nkomo VT, Gardin JM, Skelton TN, Gottdiener JS, Scott CG, Enriquez-Sarano. Lancet. 2006 Sep;368(9540):1005-11. but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy. Anatomically, the valves are part of the dense connective tissue of the heart known as the cardiac skeleton and are responsible for the regulation of blood flow through the heart and great vessels. Valve failure or dysfunction can result in diminished heart functionality, though the particular consequences are dependent on the type and severity of valvular disease. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication (translesion synthesis). Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aortic Valve
The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The aortic valve normally has three cusps or leaflets, although in 1–2% of the population it is found to congenitally have two leaflets. The aortic valve is the last structure in the heart the blood travels through before stopping the flow through the systemic circulation. Structure The aortic valve normally has three cusps however there is some discrepancy in their naming. They may be called the left coronary, right coronary and non-coronary cusp. Some sources also advocate they be named as a left, right and posterior cusp. Anatomists have traditionally named them the left posterior (origin of left coronary), anterior (origin of the right coronary) and right posterior. The three cusps, when the valve is closed, contain a sinus called an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymptomatic
In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asymptomatic. Infections of this kind are usually called subclinical infections. Diseases such as mental illnesses or psychosomatic conditions are considered subclinical if they present some individual symptoms but not all those normally required for a clinical diagnosis. The term clinically silent is also found. Producing only a few, mild symptoms, disease is paucisymptomatic. Symptoms appearing later, after an asymptomatic incubation period, mean a pre-symptomatic period has existed. Importance Knowing that a condition is asymptomatic is important because: * It may develop symptoms later and only then require treatment. * It may resolve itself or become benign. * It may be contagious, and the contribution of asymptomatic and pre-symptomat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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