Reflexive sneezing induced by light, and sunlight in particular, is estimated to occur in 18 to 35 percent of the population and is known as the photic sneeze reflex (PSR) or the ACHOO (autosomal dominant compulsive helio-ophthalmic outbursts of sneezing) syndrome. Its genetic nature has been known for at least the last 25 years. Observations that emerging from dim light into sunlight or turning to face directly into the sun commonly triggers the reflex prompted early inquiries into the trait. The number of induced sneezes--which seems to be genetically mediated and can be predicted within a family--is constant from episode to episode and typically numbers two or three. Some consequences of the PSR include danger to automobile drivers when emerging from dim light, such as a tunnel, into full sunlight, and disruption of outdoor group photos.
A concussion is an immediate but reversible traumatic paralysis of the nervous function of the brain. It is usually caused by a blow to the head or by striking the head against a stationary object. In fact, a concussion is one of eight different types of traumatic brain injuries (TBI) that most commonly result from falls, motor vehicle accidents, sporting accidents and wrongful firearms discharges. A concussion involves a host of effects (secondary injuries) that emerge several hours or days after the trauma. It is critical for physicians to monitor these secondary tissue damages, as they are frequently the origin of significant long-term effects, including brain damage, cognitive deficits, psychosocial/behavioral/emoti onal changes, bodily damage and biochemical changes at the cellular level.
Eye color is a manifestation of the pigment that is present in the iris. Brown eyes are rich in melanin deposits, and blue eyes indicate a lack of melanin. The melanocytes of the iris rest in a richly innervated psuedosyncytium, which is necessary to maintain eye color. Two genes control eye color: EYCL3, found on chromosome 15, which codes for brown/blue eye color (BEY), and EYCL1, found on chromosome 19, which codes for green/blue eye color (GEY). Although previously believed to be inherited in simple Mendelian fashion, eye color has proved to be a polygenic trait. Precisely how these genes interact to provide the full constellation of colors, such as hazel and gray, is as yet unknown. Furthermore, other genes may determine the pattern and placement of pigment in the iris, thereby accounting for solid brown as opposed to rays of color.
There are a few well-known syndromes of which heterochromia iridis is a striking feature. Waardenburg syndrome type 1, an autosomal dominant disorder caused by mutations in the PAX3 gene, is characterized by pigmentary disturbances of the iris, hair and skin, as well as congenital sensorineural hearing loss. But two different eye colors tends to be an isolated finding, which adds to the seemingly endless and fascinating variation in humans' physical characteristics.
Onion is a rich source of nutrients, including vitamins B, C and G, protein, starch and a series of essential elements. The chemicals contained in onions are reported to be effective agents against fungal and bacterial growth; they protect against stomach, colon and skin cancers; they have anti-inflammatory, antiallergenic, antiasthmatic and antidiabetic actions; and they treat causes of cardiovascular disorders, including hypertension, hyperglycemia and hyperlipidemia while also inhibiting platelet aggregation.
The volatile oils that help to give Allium vegetables their distinctive flavors contain a class of organic molecules known as amino acid sulfoxides. Peeling, cutting or crushing an onion's tissue releases enzymes called allinases, which convert these molecules to sulfenic acids. The sulfenic acids, in turn, spontaneously rearrange to form syn-propanethial-S-oxide, the chemical that triggers the tears. They also condense to form odorous thiosulfinates, coincidentally evoking the pungent odor associated with chopping onions and eliciting the false accusation that it is the odor that causes the weepy eye.
The front surface of the eye--the cornea--serves several purposes, among them protection against physical and chemical irritants. The cornea is densely populated with sensory fibers of the ciliary nerve, a branch of the massive trigeminal nerve that brings touch, temperature and pain sensations from the face and front of the head. The cornea also receives a smaller number of autonomic motor fibers that activate the lachrymal (tear) glands. Free nerve endings detect syn-propanethial-S-oxide on the cornea and drive activity in the ciliary nerve--which the central nervous system interprets as a burning sensation--in proportion to the compound's concentration. This nerve activity reflexively activates the autonomic fibers, which then carry a signal back to the eye ordering the lachrymal glands to wash the irritant away.
Gaucher (pronounced Go-SHAY) disease is a rare genetic disorder affecting fewer than 10,000 people worldwide. It is caused by deficiency of the enzyme glucocerebrosidase, which breaks down a certain lipid, or fat, in the body's cells called glucocerebroside. Without this enzyme, the lipid builds up, causing the disease's symptoms. Symptoms include anemia, fatigue, and enlarged liver and spleen. Patients can also suffer from easy bleeding and bruising, and deterioration of bones, leading to frequent fractures.
The only therapy for Type 1 Gaucher disease is Cerezyme* (imiglucerase for injection), a recombinant drug developed by Genzyme General of Cambridge, Mass. Cerezyme stops and reverses the symptoms of Gaucher disease, allowing patients to live normal, healthy lives. Cerezyme and its predecessor, Ceredase*, have been available for nearly 10 years. Gaucher disease is the most prevalent lysosomal storage disorder, caused by an inherited enzymatic defect with consequent accumulation of undegraded glucocerebroside in monocyte-macrophage cells, the so-called Gaucher cells. Diagnosis of the disease is via assay of decreased glucocerebrosidase activity in peripheral blood samples, in conjunction with DNA mutation analysis. Nonetheless, neither quantity of residual activity nor specific genetic makeup (genotype) can accurately predict the type or degree of severity of the disease (phenotype), except in a broad sense.
Scleroderma, meaning "hard skin," takes its name from one of the more obvious symptoms of this illness. The disease causes thickening and hardening of the skin and damages arteries, joints and internal organs such as the lungs and kidneys. The treatment of scleroderma follows the various aspects of the disease as just described. The change in skin color associated with Raynaud's phenomenon indicates a dramatic loss of the normal blood supply to the fingers, which should be avoided or treated immediately. A warm bath is one of the fastest and most effective ways to warm the fingers. In emergency situations, the fingers can be placed under the warmer parts of the body, such as the armpits and the abdomen. If the Raynaud's phenomenon is not treated, the patient may develop digital ulcers or sores, requiring amputation of the finger tips in extreme cases. Most of the patients suffering from scleroderma have antibodies (produced by the B cells) that bind self components. There are two main kinds of antibodies involved in scleroderma, anticentromere antibodies, and anti-topoisomerase-I antibodies.
September 23rd 2011 13:51
Ultraviolet (UV) light kills cells by damaging their DNA. The light initiates a reaction between two molecules of thymine, one of the bases that make up DNA. The resulting thymine dimer is very stable, but repair of this kind of DNA damage--usually by excising or removing the two bases and filling in the gaps with new nucleotides--is fairly efficient. Even so, it breaks down when the damage is extensive. The longer the exposure to UV light, the more thymine dimers are formed in the DNA and the greater the risk of an incorrect repair or a "missed" dimer. If cellular processes are disrupted because of an incorrect repair or remaining damage, the cell cannot carry out its normal functions. At this point, there are two possibilities, depending on the extent and location of the damage. If the damage is not too extensive, cancerous or precancerous cells are created from healthy cells. If it is widespread, the cell will die.
Basically, UV kills cells because of the accumulation of DNA damage. A gene product, called p53, is one of the responsible parties for slowing the cell cycle and checking for damage. If the damage is fixable, p53 sends in the repair machinery. If the damage is too extensive, it directs the cell to apoptosis, or programmed cell death.
Blood that remains in the human umbilical cord and placenta after birth supplies doctors with a rich source of hematopoietic progenitor cells (stem cells), the precursors of all other blood cells. Bone marrow from donors has traditionally been used as a source of stem cells for restoration of diseased bone marrow, but researchers have demonstrated that cord blood provides an excellent alternative source. Thus, cord blood is utilized for the treatment of many diseases--such as leukemia, sickle cell anemia and Hodgkin's disease--that are typically remedied by bone marrow transplants. There appear to be several advantages to using stem cells from umbilical cord blood, including rapid availability, potential to expand the ethnic diversity of the donor pool (minorities are vastly underrepresented in bone marrow donor pools), no donor risk, less likelihood of viral contamination and less risk of graft-versus-host disorder (GVHD). GVHD is a significant consideration because stem cells from a donor's bone marrow often recognize the host as foreign, resulting in complications after transplantation. Cord blood stem cells are potentially less immunologically active and may pose less risk of GVHD than stem cells from bone marrow. The future holds great promise for the use of umbilical cord blood stem cells. In the transplantation discipline, collection of data from clinical trials will continue to improve knowledge, thereby helping to increase survival rates.
Tissue engineering integrates the sciences of biomaterials, cell biology, biochemistry, biomedical engineering and transplantation to create tissue and organ substitutes. Starting with a few human cells, tissue engineers simulate the environments that allow cells to develop into viable tissue. The primary motivation behind tissue engineering is the ongoing, dire need for available, safe and transplantable organs and tissues. Every year thousands of people die waiting for hearts, livers, lungs and kidneys simply because there aren't enough transplantable organs to go around. Similarly, the need for other human tissues such as skin and cartilage is constant, and the availability (or lack thereof) can make a real difference in the lives of burn and accident victims. Tissue engineering has the potential to redefine tissue and organ repair and replacement. Tissue engineering will soon address the tremendous number of problems seen by patients who require replacements of skin, bone and other tissues and organs.
Muscle stiffness is caused when the muscles in a certain area of the body contract and become tense. Muscle stiffness can sometimes occur if you don’t warm up and cool down before and after a workout. When you perform strenuous exercise and you have not stretched your muscles you usually develop muscle stiffness the next day. Sometimes the stiffness lasts several days. If muscles are healthy, muscle stiffness may be caused from an insect bite, an infection, an injury or possibly bleeding in the muscle and various medical conditions. Stiff muscles in the neck area can be caused by something as simple as poor sleeping posture or being exposed to cold weather for long periods of time. It can be caused by physical conditions that stem from an injury, whiplash, arthritis or various spinal disorders.
Halogen bulbs are versatile, provide a good source of light and last slightly longer than regular bulbs, but have no reported ill-effects to humans. Halogen bulbs are safe if used continuously for several hours. They are dangerous only if they are overheated as this can lead to catch on fire. Their advantage is that they last for a long time. Moreover, if you touch it with your bear figures than it can the bulb can be damaged. In 1992, the University of Genoa in Italy released a study linking halogen bulbs to skin cancer. The FDA claims that there isn't enough evidence to warrant action. Although halogen bulbs burn longer than traditional light bulbs, but not as long as compact fluorescent bulbs, they can pose a fire hazard as they burn very hot. The biggest caution has to be keeping the bulbs away from drapes or other flammable materials and avoid touching them. Many fire departments around the world have issued warnings about them. In certain types of fixtures can be dangerous. Torchiere lamps should not be used around children because they can be easily knocked over and cause a fire. Halogen lamps, however, have a higher incidence of exploding and/or catching fire than florescent or incandescent bulbs.
Endometriosis is a condition in females where endrometrial cells, typically found in the uterine cavity, are deposited in inappropriate locations. Endometriosis is a condition in which the uterine lining grows on other parts of the body (typically in the pelvic area). These cells are intended to line the uterine cavity, but often during years of reproduction an egg implantation outside of the uterus will cause the endometrial cells to deposit outside of the uterus. The most common symptom is pelvic pain. This pain correlates to a women's menstrual cycle and can be severe and in some cases debilitating. Endometriosis affects women in their reproductive years. Endometriosis can be treated with medications, such as, NSAIDS and other anit-imfammatories.
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