Friday, October 29, 2010
Doctors rely on genetic testing in many conditions, most of them involving pregnant women or infants. However, they may also be used in adults to see if they carry a risk factor for a disease before the symptoms even begin to show up. Doctors use genetic tests for several reasons. These include:
•Finding possible genetic diseases in unborn babies
•Finding out if people carry a gene for a disease and might pass it on to their children
•Screening embryos for disease
•Testing for genetic diseases in adults before they cause symptoms
•Confirming a diagnosis in a person who has disease symptoms
People have many different reasons for being tested or not being tested. For many, it is important to know whether a disease can be prevented or treated if a gene alteration is found. In some cases, there is no treatment. But test results might help a person make life decisions, such as career choice, family planning or insurance coverage.
How do you feel about genetic testing?
Thursday, October 28, 2010
Polygenic traits are traits that are controlled by several different genes. Usually these traits exist on a continuum of expression. For example consider height; there are not just two types of height but instead normal height exists on a fairly large continum of about 12 inches. Where you fall in this height range is caused by genetic material on several different genes. Other examples of the influence of multiple genese can be seen in skin color, autism, hypertension, hair color and eye color.
First let's start with a few definitions.
With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits. With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.
Here are a couple of examples: Incomplete dominance is seen in wavy hair. It is a new phenotype that occurs when one parent has straight hair and one parent has curly hair. An example of condominance is found in blood types. The blood type AB is made up of both A proteins and B proteins.
Friday, October 22, 2010
According the the manufacture, Johnson and Johnson, DERMABOND® is an adhesive material which forms a strong microbial shield to protect wounds while they heal.
DERMABOND® wears off naturally during the healing process, which is usually completed within 7 to 10 days. It appears that this material can take the place of stitches.
Hydrogels are also used for wound but their purpose is to provide a moist environment for wound healing. Johnson and Johnson also makes a hydrogel product called Nu-gel.
Thursday, October 21, 2010
Actually, they don't.
Jeffrey Mogil, Ph.D., is professor of pain studies at McGill University in Montreal, Canada. He explains that while not all studies have found sex differences, those which have all point in the same direction that contradicts conventional wisdom. "Females are more sensitive to pain, less tolerant and more able to discriminate different levels of pain than males," he says. This is true in studies of both humans and animals.
Another really interesting finding from Dr. Mogil relates to pain and hair color.He found that natural red heads (female only) experience pain differently from blondes or brunettes. This was not true in males. "It turns out that processing pain involves a receptor which, when mutated, produces red hair and fair skin, among other changes. This receptor—the MC1r receptor— was initially thought to occur only in the skin. However, it has now been found in the brain, and there, in women, it's part of the pathway that processes pain."
Another great question on cancer!
Inheriting cancer in vitro is extremely rare. It appears that only 30 documented cases show the infant received cancer from the mother before birth. There was previously no genetic evidence to explain why a child’s immune system would not recognize and destroy any invasive cancer cells that were of maternal — and therefore, foreign — origin.
The new study, led by Mel Greaves, of the Institute of Cancer Research (ICR), and published in Proceedings of the National Academy of Sciences, used advanced genetic fingerprinting to prove that an infant’s leukemic cells were unquestionably of maternal origin.
The case, involving a Japanese mother aged 28 and her daughter, revealed that both patients’ leukemic cells carried the identical mutated cancer gene BCR-ABL1 even though the infant had not inherited this gene.
This meant that the child, who had cancer diagnosed at 11 months old, could not have developed this type of leukemia in isolation.
Heart cancer is extremely rare and is referred to as cardiac sarcoma (cancer of a soft tissue). The number of people dying of heart cancer is combined with those dying of all soft tissue cancer and is estimated to be 4,000 people in 2010.
Many people diagnosed with heart cancer had a primary cancer close to the heart like melanoma and then it went on to invade the heart cells too. Tumors found in the heart are usually benign and can be removed.
It looks like research articles on cyclin have been published regularly over the past twenty years. In fact the 2001 Nobel Prize in Physiology or Medicine was awarded for the discovery of CDKs and cyclins and the complete description of cyclin and cyclin-dependent kinase mechanisms.
You remember from our textbook that when cyclin is injected into a non-dividing cell it begins to form spindles and goes into cell division. A research article published in 2008 found that cyclin d1 is over-expressed in human breast cancer. These findings may explain how cyclin d1 contributes to breast tumor growth, and provides the rationale for targeted therapies in humans.
In April 2010, over 50 abstracts were presented at the American Association of Cancer Research meeting dealing with cyclins and ways to inhibit the cyclin dependent kinase. It looks like a very promising area of cancer study.
Sources: ErbB2 Induces Notch1 Activity and Function in Breast Cancer Cells Clinical
and Translational Science Volume 1, Issue 2, pages 107–115, September 2008
Studying about cell division always brings up great questions about cancer.
One very recent discovery is the develop of blood vessels in tumors which serves as a pipeline for nourishment. It appears that tumors have hormone receptors that allows a hormone called FSH (follicle stimulating hormone) to bind and start forming new blood vessels. This receptor was found in 11 different types of tumors and the race is on to see if compounds can be used to block the receptor or inhibit the protein.
Source: A. Radu et al. Expression of follicle-stimulating hormone receptor in tumor blood vessels. New England Journal of Medicine, Vol 363, Oct 21, 2010, p.1621.
Friday, October 8, 2010
Sleep consists of three stages plus a stage of rapid eye movement know as REM. When a person enters stage 3, extremely slow brain waves called delta waves are interspersed with smaller, faster waves which progress into delta waves almost exclusively. Stages 3 is referred to as deep sleep or delta sleep, and it is very difficult to wake someone from it.
In deep sleep, there is no eye movement or muscle activity. This is when some children experience bedwetting, sleepwalking or night terrors. Adults spend about 20%of their sleep time in REM and about 15% of their time in Stage 3.
Eye color is genetically determined and is not as simple as once thought. The color of the eye is determined by multiple genes allowing for many different shades of gray, gree, blue and brown.
Eye color can change as a person grows older although most colors are permanent by age one.
Thursday, October 7, 2010
Cells growth and division is controlled by genes. One part of the gene stimulates and growth and another part of the gene restrains it. Those two pieces need to work in perfect harmony in order to have a normal rate of cell division. When cells divide much faster than usual they form a tumor. All cancers develop from a primary tumor.If the tumor sheds cells in the blood or lymph they will go on to form a secondary tumor elsewhere in the body.
Wednesday, October 6, 2010
The beauty of a stem cell is that it can develop into any type of cell. The stem cell is described as being pluripotent meaning that it is capable of generating any and all cells in the body under the right conditions.
So theoretically, a stem cell can be grown into a muscle cell however, right now the focus of researchers is on repairing diseased cells with new ones. So stem cells grown into muscle cells would be used to help someone with Muscular Dystrophy not a body builder.
Bruises hurt because they are the physical evidence of an injury. When a bruise appears it means that the tissue below has been damaged and blood vessels have broken beneath the skin. The swelling of the area due to escaping blood irritates the nerve endings in the area and you perceive pain.
Light bruising usually fades in about one week.