Whether a student still in training or a veteran of the job, this blog is dedicated to refreshing the mind with all that relates to the field of Clinical Laboratory Sciences.

Tuesday, August 24, 2010

The history of the pregnancy tests

From early Egyption days to the "rabbit" test the pregnancy test has progressed a long way towards today's modern stick test.

Taken from Mental Floss @ http://www.mentalfloss.com/blogs/archives/14656

Dead Rabbits & Other Historical Pregnancy Tests
by Sara Newton - May 5, 2008 - 3:59 PM

In the ubiquitous Baby Mama trailer, Tina Fey looks at a used home pregnancy test that mocks her with a foreboding blue “NO” in the results box. Although the mock factor is optional, home pregnancy tests can lay it out straight: YES or NO. Whether the results are determined by blue lines, a plus or minus sign, or the plain words, the “pee on a stick” method is a popular way to discover if one is with child. Isn’t it interesting that one of life’s greatest achievements (new life) can be diagnosed by one of life’s most common routines (peeing, albeit on a prophetic stick)? Also as fascinating, this dichotomy existed long before the FDA approved the first home pregnancy test in the 1970s.

Knocked up like an Egyptian
The earliest recorded “peeing on a stick” test comes from those innovative Egyptians. In 1350 B.C., in between building pyramids and wrapping sarcophagi, someone produced a document describing how to determine pregnancy. You guessed it; a speculating woman must urinate on wheat and barley seeds, of course! The ancient papyrus read, “If the barley grows, it means a male child. If the wheat grows, it means a female child. If both do not grow, she will not bear at all.” In 1963, testing this theory found it 70 percent accurate, as the urine of pregnant women contains elevated levels of estrogen that may promote growth in these grains. As far as the gender guessing, that was Ra having a chuckle.

The Sample is in the Chamber Pot
Starting in the Middle Ages and up until the 17th century, “piss prophets” diagnosed many different conditions and diseases based on the color of urine. Since proven unscientific and often incorrect, this medical practice known as a “Uroscopy” often referred to a handy Uroscopy Wheel to help with diagnosis. A 1552 European document described pregnancy urine as a “clear pale lemon color leaning toward off-white, having a cloud on its surface.” The aptly named prophets employed another pregnancy test where they mixed urine and wine and watched the alcohol reacting with certain present proteins. In yet another dubious 17th-century test, a ribbon was dipped in a woman’s urine and burned. If the smell nauseated her, baby was on the way!

The Mouse Died
Fast-forward to the early 20th century, when scientists first discovered the role hormones played in female reproduction, they identified a specific hormone found only in pregnant woman, human chorionic gonadotropin (hCG). In the 1920s and 30s, to recognize the presence of hCG, which indicated pregnancy early on, doctors injected urine into an immature mouse, rat, frog, or even a rabbit. If a woman were pregnant, the test subject would go into heat despite its immaturity. To announce their status, women euphemized, “The mouse died” or “I killed the Easter bunny,” because killing and dissecting the lab animal confirmed the results. A common misconception arose that if the animal died after injection, it pointed to a positive pregnancy test. But in actuality, all tested specimens were disposed of, much to the chagrin of animal rights activists. This test was known as the A-Z test, named after the founding scientists, Selmar Ascheim and Bernhard Zondek.

To e.p.t.and Beyond
In the 1970s, as a result of the sexual revolution and the presence of reproductive choices, Wampole’s two-hour, urine-based pregnancy test became available only to doctors and technicians. The test could be done early on, but the packaging pictured an authoritative man wearing a lab coat, implying that this test was not intended for home use. Other intimidating tools in the box included: test tubes, a plastic rack, three bottles of chemical solutions, a small funnel, pipettes, and a saline solution. What a way to create an atmosphere encouraging relaxation and sample giving!
In 1977, the e.p.t. (which originally stood for “early pregnancy test,” and is now the more comforting “error proof test”) became the first home pregnancy test on the U.S. market. The test took two hours and was more accurate when dealing with positive results. In 1978, an issue of Mademoiselle described the original e.p.t.: “For your $10, you get pre-measured ingredients consisting of a vial of purified water, a test tube containing, among other things, sheep red blood cells…as well as a medicine dropper and clear plastic support for the test tube, with an angled mirror at the bottom.”
Home pregnancy tests evolved to the stick we know now and are still evolving. In 2003, Clearblue Easy’s digital pregnancy test ushered in a new generation of home pregnancy tests. In place of a thin blue line, the indicator screen says either “pregnant” or “not pregnant.” But if still skeptical, one can always go into a doctor’s office for a blood serum test for a definitive answer. Or maybe he has some barley or wheat that have a second opinion.

Sara Newton is an occasional contributor to mental_floss.

Sunday, August 15, 2010

Rheumatoid Factor

Rheumatoid factor (RF) is an autoantibody that is produced by the body in response to certain disease states. Rheumatoid factor is usually an IgM antibody; however other classes of immunoglobulins can be produced. The antibody targets the Fc region of human IgG that is altered in protein structure. The RF autoantibodies attach themselves to healthy tissues throughout the body causing damage. The body can produce rheumatoid factor in response to various illnesses however it is most commonly measured to help diagnose potential cases of Rheumatoid Arthritis and Sjogren’s syndrome.

Rheumatoid factor can be present in a variety of illnesses. Around 75% of patients with Rheumatoid arthritis or Sjogren’s syndrome will present with a positive RF test. The remaining percentage of people with these two diseases will present with a negative level of RF or have very low levels. High RF levels can be found in patients with other autoimmune diseases such as lupus, scleroderma, and vasculitis. Positive RF tests can also be associated with diseases such as tuberculosis, malaria, hepatitis, endocarditis, and leukemia. Because RF levels may or may not be present in a patient with a specific illness RF is not used to definitively diagnose any disease.

Rheumatoid factor is measured in conjunction with other tests to help make a diagnosis. If Rheumatoid arthritis or Sjogren’s syndrome is suspected, a clinician might order other autoantibody tests such as an ANA (antinuclear antibody), anti-SS-A, or anti-SS-B to help differentiate between all possibilities. Performing a CRP level or a Sedimentation rate can help to determine if there is inflammation present. A newer test called the Cyclic Citrullinated Peptide Antibody (CCP) test can be ordered to detected early onset Rheumatoid Arthritis. This test can be performed in the event that RF levels are negative and the clinician still suspects Rheumatoid arthritis. Clinicians will use results from a variety of tests along with clinical findings to diagnose a patient with Rheumatoid arthritis.

Rheumatoid factor testing can be performed either by agglutination assays or through nephelometry. Here at BSHS we perform RF testing on the Dimension Vista system. The Vista uses nephelometry to measure levels of rheumatoid factor in a sample. The reagent includes polystyrene particles that are coated with anti-human IgG and a phosphate buffer. When the reagent is added to a patient’s sample any rheumatoid factor present will bind to the anti-human IgG. The aggregates that are formed scatter light in direct proportion to the concentration of RF present.

Normal values for rheumatoid factor can vary depending on testing methods. Agglutination methods will report results out as a titer. Nephelometric methods will report out rheumatoid factor as a unit of concentration. For the method utilized by the Dimension Vista, the normal range is less than 15 IU/mL. Factors that can affect results include excessively lipemic and icteric samples. Age can play a factor as well. High RF levels can be found in up to 10% of people over the age of 65 years. These potential false positive results should be taken into account when determining a diagnosis.

Rheumatoid factor is an autoantibody produced by the body for unknown reasons. It attaches to various tissues in the body causing damage and subsequent illness. Clinicians will measure levels of rheumatoid factor in the body in order to determine if a patient potentially has rheumatoid arthritis or Sjogern’s syndrome. While there is no definitive test to diagnosis rheumatoid arthrisis, testing for RF in conjunction with others assays and clinical findings can help clinicians in diagnosing potential cases of rheumatoid arthritis.

• SIEMENS Dimension Vista Flex reagent cartridge. (2008). RF. (REF K7068). Newark, DE: Siemens Healthcare Diagnostics Inc.
• Rheumatoid Factor. (2010). Rheumatoid Factor: The Test. Lab Tests Online. Retrieved on July 18, 2010 from http://www.labtestsonline.org/understanding/analytes/rheumatoid/test.html
• Arthritis Health Center: Rheumatoid Factor. (2008). Rheumatoid Factor. WebMD. Retrieved on July 18, 2010 from http://www.arthritis.webmd.com/rheumatoid-factor-rf

Sunday, August 8, 2010

Sickle Cell Disease

What Is Sickle Cell Disease?
By Rachael Rettner, LiveScience Staff Writer

posted: 30 July 2010 10:38 am ET

Sickle cell disease gets its name from the distorted shape of a patient's red blood cells, which are sometimes C-shaped rather than the normal doughnut shape. The cells' disfigurement comes from the presence of abnormal hemoglobin — a protein in red blood cells that carries oxygen throughout the body. Not all red blood cells are sickle shaped all the time — they take on the shape in response to a stressor, such as lack of oxygen, dehydration or infection.

The disease is hereditary. People who have two copies of the sickle cell gene, one from each parent, are said to have sickle cell anemia, the most severe form of the disease. People with one sickle cell gene are said to have sickle cell trait. They don't show symptoms, but can pass the gene on to their children.

Having just one copy of the gene confers protection against malaria. This protection is thought to be why the genetic mutation has stuck around over the course of evolution. It may also explain why the disease primarily affects those who descend from tropical or subtropical countries (where malaria is prevalent), including Africa, South America, Central America and India. In the United States, 70,000 to 100,000 African Americans are estimated to have sickle cell anemia, or 1 out of every 500 births in this population, according to the Centers for Disease Control and Prevention (CDC). About 1 in 12 African Americans has sickle cell trait. The condition occurs in 1 out of every 36,000 Hispanic American births. And around the world, the disease affects millions of individuals.

The abnormal sickle cells are less flexible than normal red blood cells and can also stick together and form clumps, which can cause a number of problems. The cells can block blood vessels and restrict blood flow, which can lead to pain, organ and nerve damage, and stroke.

"People can have problems in any part of their body," said Marsha Treadwell, a sickle cell disease researcher at Children's Hospital Oakland Research Institute (CHORI) in California. "Blood flows everywhere."

The sickle cells also don't live as long as normal red blood cells, lasting around 20 days instead of the usual three months. As a result, patients experience anemia.

Recent advances in pediatric care have led to a decrease in the mortality rate for the disease in children. From 1999 to 2002, sickle cell-related death among African-American children less than 4 years of age fell by 42 percent, according to the CDC. However, the average life expectancy for those with sickle cell disease in the United States is still 30 years shorter than the average lifespan of healthy adults.

By age 45, 24 percent of sickle cell patients have had a stroke, said Elliott Vichinsky, a hematologist at CHORI. But even without having a stroke, the condition may lead to cognitive problems.

In a recent study, Vichinsky found adult sickle cell patients with no history of brain problems performed worse on cognitive tests than controls matched from the community after adjusting for age, gender and education. The result suggests sickle cell patients may have problems with everyday tasks such as multitasking, remembering appointments and carrying out their jobs. The researchers suspect the cognitive problems might be due to a lack of oxygen being delivered to the brain, and so, in many cases, the problems could be reversible. The study was published May 12 in the Journal of the American Medical Association.

Current treatments involve blood transfusions to treat anemia and help prevent stroke, and pain medication for pain episodes. The only sickle cell-specific drug available, known as hydroxyurea, helps alleviate pain and can reduce the rate of mortality in patients.

A bone marrow transplant can cure the disease, but this option is not available for many people because the transplant needs to be matched exactly.

Full article @ http://www.livescience.com/health/what-is-sickle-cell-disease-100730.html

Sunday, August 1, 2010

Credit-card sized microfluidics

Laboratory in microdrops: Credit card-size microflow system handles thousands of experiments

ScienceDaily (2010-07-29) -- Tens of thousands of chemical and biochemical experiments may be conducted daily with the use of a microflow system of the size of a credit card, developed by scientists in Poland. The device has already been tested in research on the effectiveness of antibiotic mixtures. ... > read full article