Sunday, July 25, 2010
The concentration of prealbumin in a patient’s serum will increase or decrease rapidly in response to a patient’s nutritional status. Increases in concentration can occur due to drug therapy with high-dose corticosteroids or high-dose nonsteroidal anti-inflammatory drugs. Increases in prealbumin can also be seen in Hodgkin’s disease and kidney failure. It is not typical to use prealbumin testing to monitor these conditions. Decreases in the concentration of prealbumin are more serious and are a sign of malnutrition. A decreased concentration of prealbumin can be found in chronic illnesses such as cancer or AIDS, in patients with hyperthyroidism, in sepsis, and in liver disease. Other conditions that can lead to malnutrition include protein-losing gastrointestinal illnesses, eating disorders such as anorexia, massive trauma, pancreatitis, and severe burn victims. All of these diseases and disorders can result in a decreased concentration of prealbumin.
Prealbumin levels can also be used to monitor the effectiveness of nutritional therapy. Physicians will order prealbumin levels on patients who are scheduled for surgery or hemodialysis in order to determine if a patient will have a negative or diminished outcome to treatment. Patients with a normal prealbumin level are better nourished and will recover more quickly from these types of treatments. Prealbumin levels can also be used to monitor the effectiveness of parenteral nutrition therapy. If a patient is responding to nutritional therapy then prealbumin levels should increase about 1 mg/dL per day.
Normal ranges for prealbumin concentration can vary slightly between laboratories however a general range is 20-40 mg/dL. Here at BSHS we are running prealbumin on the Dimension Vista system. This assay detects the concentration of prealbumin in serum using an antiserum. The antiserum combines with the prealbumin to form immune complexes that are detected via nephelometry. These immune complexes create light scatter that is directly proportional to the concentration of prealbumin in the sample.
Prealbumin is an ideal marker for nutritional status. It has a short half-life and reacts quickly to changes in a patient’s diet. It contains within it a wide variety of essential and non-essential amino acids that are used throughout the body. Because of its structure it is a better marker for nutritional status than albumin levels alone. When available it is the preferred test for determining the nutritional status of a patient.
· Burtis, C. A., Ashwood, E. R., Bruns, D. E., Tietz Textbook of Clinical Chemistry & Molecular Diagnostics. St. Louis, Missouri: Elsevier (2006). 563-564.
· SIEMENS Dimension Vista Flex reagent cartridge. (2008). Prealbumin. (REF K7064). Newark, DE: Siemens Healthcare Diagnostics Inc.
· Prealbumin. (2009). Prealbumin: The Test. Lab Tests Online. Retrieved on July 24, 2010 from http://www.labtestsonline.org/understanding/analytes/prealbumin/glance.html#
· Prealbumin. (2010). Prealbumin. Clinlab Navigator. Retrieved on July 24, 2010 from http://www.clinlabnavigator.com/index.php?option=com_content&view=aritcle&id=473&letter=P
Tuesday, July 20, 2010
by Tonic, on Tue Jul 13, 2010 5:45am PDT 1815
From Yahoo News Healthy Living
We already know that we need to eat plenty of leafy greens to stay healthy, but who knew that a salad spinner itself could help save lives?
As we learn from EurekAlert, Rice University undergraduates Lila Kerr and Lauren Theis were presented with an assignment in their Introduction to Bioengineering and World Health class. As Theis explains:
"We were essentially told we need to find a way to diagnose anemia without power, without it being very costly and with a portable device."
In a solution short on cost but long on ingenuity, the duo modified a basic, everyday salad spinner into an easy to use and transport centrifuge that successfully separates blood to allow diagnosis of anemia with no electricity. The device costs about $30, can process 30 individual 15 microliter blood samples at a time, and can separate blood into its component red cells and plasma in about 20 minutes.
"Sally Centrifuge," as the innovation has been dubbed by its creators, is undergoing a series of field tests this summer in places that will benefit from the availability of effective but low-tech solutions and adaptations. As part of Rice University's Beyond Traditional Borders (BTB), a global health initiative focused primarily on developing countries, Kerr and Theis are traveling along with their device to Ecuador, Swaziland and Malawi, where rural clinics will provide real-world testing of the surprising diagnostic tool.
In rural, under-served and impoverished parts of the world, a positive diagnosis for anemia is a critically important clue when looking for other health problems such as malnutrition, or serious chronic infectious diseases such as malaria and HIV/AIDS. Until now, blood samples taken in the field would have to be sent to a distant location complete with expensive laboratory centrifuges and electricity, while patients would be left waiting for the results — a lapse in time that can be deadly. Being able to diagnose the condition in real time with "Sally Centrifuge" would allow appropriate treatment to begin before before an illness progresses and a patient's condition deteriorates too drastically.
Maria Oden, engineering professor and co-adviser to the team, reflects on how successfully the two young women approached the assignment by providing something that may literally save lives as it is brought to bear on pressing health challenges in rural and economically under-developed regions of the world:
"The students really did an amazing job of taking very simple, low-cost materials and creating a device their research shows correlates nicely with hematocrit levels in the blood. Many of the patients seen in developing world clinics are anemic, and it's a severe health problem. Being able to diagnose it with no power, with a device that's extremely lightweight, is very valuable."
Have an innovative idea for re-purposing a household gadget yourself? Share it in a comment below!
Photo by Jeff Fitlow/Rice University.
Read more Weird Science stories at Tonic!
Sunday, July 18, 2010
By Amanda Gardner
HealthDay Reporter by Amanda Gardner
healthday Reporter 13 mins ago
SUNDAY, July 18 (HealthDay News) -- Almost half of HIV-negative people who participate in clinical trials for HIV vaccines end up testing positive on routine HIV tests -- even though they're not actually infected, a new study shows.
The reason: They underwent what experts call "vaccine-induced seropositivity/reactivity" (VISP), meaning that they possess immune system antibodies to the virus but not the virus itself. That's an important distinction, since routine HIV screening looks for virus antibodies only.
Experts pointed out that the results are not new or surprising, but simply underline the delicacies of conducting trials into HIV/AIDS.
"You need to make sure to use other forms of testing for HIV, for example, viral load or p24 antigen, not just HIV antibodies. And people who've been in trials need to know their antibody status by the end of the trial," said Dr. Michael Horberg, director of HIV/AIDS at Kaiser Permanente in Santa Clara, Calif. "If it is a false positive but they do not have HIV infection, that would be very important for them to know, especially if they do repeat testing as part of good preventive health."
But a positive test can still carry stigma as well as insurance repercussions, noted Dr. Jerome F. Levine, an infectious diseases specialist with Hackensack University Medical Center in New Jersey, adding that "trials have had trouble recruiting people for this very reason."
The findings are simultaneously being presented Sunday at the International AIDS Conference in Vienna and published in the July 21 issue of the Journal of the American Medical Association (JAMA).
In this study of almost 2,200 people -- all participants in HIV vaccine trials -- 41.7 percent underwent VISP and tested positive for HIV antibodies. And those rates differed depending on the type of vaccine administered, ranging from 6.3 percent to 86.7 percent.
A second study, also being presented at the conference and published in JAMA, found that a screening program used in emergency departments where patients can "opt out" did not turn up very many new cases of HIV. These types of screening programs routinely test people entering the emergency room, regardless of their suspected level of risk or the presence or absence of symptoms.
The study compared the effectiveness of the test in turning up new cases of HIV infection versus tests ordered directly by a doctor.
The "opt-out" program started being recommended by the U.S. Centers for Disease Control and Prevention in 2006, but only in locales where the rate of undiagnosed cases of HIV infection rose above 0.1 percent.
Most health care facilities in the United States still don't use the opt-out method, said Levine.
This study took place in a Denver emergency department that annually sees about 55,000 patients. The hospital alternated from physician-directed testing to opt-out testing every four months over the course of two years.
First of all, the study found that only 25 percent of patients in the opt-out group actually agreed to a test.
Furthermore, close to 7,000 people were screened but only 0.15 percent turned out to be HIV-positive. Only 1 percent of the more than 21,000 patients who opted out were screened later and only 2.2 percent of those were found to be HIV-positive.
The small number of people who underwent HIV testing -- only one-quarter -- is a big limitation to the study, said Horberg, but that doesn't mean that such programs don't have value.
"Just because someone has a negative test, that doesn't mean that that testing wasn't successful," he said. "It may have raised the awareness of the patient. It may be prompting them to change their behavior and to really do an analysis of what good preventive health they need to follow."
A third paper in the journal recommended that all cancer patients be screened for HIV. This might sway cancer treatment decisions, for instance, helping doctors and patients avoid drugs that suppress the immune system, the authors noted.
There's more on HIV/AIDS at the U.S. Centers for Disease Control and Prevention.
CSF can be collected for both therapeutic and diagnostic purposes. In the event that intracranial pressure is increased CSF can be collected in order to relieve pressure inside the brain. CSF obtained for laboratory analysis can reveal the presence of inflammation, trauma, infections, or even malignancies. CSF can be collected from a variety of sites, however it is most often collected using a lumbar puncture. In this case a needle is inserted into the space between vertebrae in the lumbar portion of the spine in order to remove CSF. In the event that a lumbar puncture cannot be performed a cisternal puncture or a ventricular puncture can be used. A cisternal puncture is done with fluoroscopy, and involves placing the needle below the occipital bone of the skull in order to obtain a sample. A ventricular puncture is usually done in the operating room and involves inserting a needle directing into one of the ventricles of the brain. Lastly samples can be obtained from shunts that have been placed either in the spinal column or in the ventricles. Up to 20 mL of fluid can be obtained for analysis and is collected 2-4 mL at a time into three separate sterile tubes. Each tube should be labeled in the order that it is collected. The first tube collected is used for the analysis of chemistries, serology, and if needed a beginning cell count. The second tube is used for microbiological analysis. The third tube is used for a final cell count and morphology. Cell counts should be done within one hour of collection since cells degrade rapidly in CSF. Cell counts can also be paired (performed on tubes 1 & 3) in order to rule out the presence of contamination due to a traumatic tap.
In a normal healthy patient CSF is clear, colorless, and contains only a few cells. It can have up to five leukocytes per cmm but should not have any erythrocytes present. The leukocytes most often seen are lymphocytes and monocytes. Because the brain requires proteins and glucose for nourishment it is normal to find these molecules in CSF. A normal sample of CSF has a total protein level around 15-45 mg/mL and a glucose level around 40-70 mg/mL. These values can change in response to a disruption in the blood-brain barrier. There are several instances where CSF protein levels will be increased. Mild increases can occur due to inflammation caused by diseases such as meningitis, encephalitis, presence of tumors, hemorrhage, and stroke. Bacterial meningitis will cause a much larger increase in CSF protein concentration. Severe increases in protein concentration can be found in patients with Guillain-Barre syndrome. For patients with multiple sclerosis the increase in protein concentration is mild however there will be a specific elevation in IgG which can be quantified via separate testing. A decrease in CSF protein concentration is a sign that the body is producing CSF rapidly either due to illness or injury. Increases in CSF glucose are a reflection of high serum glucose levels. Most often CSF glucose concentrations will present as normal to decreased. A decrease in CSF glucose can be a sign of bacterial or fungal infection as these organisms utilize the glucose available to them. Tumors and leukocytes will also utilize glucose and increased concentrations of these cells can lead to a decrease in the concentration of CSF glucose. When performing a cell count and differential it is important to note the numbers and types of cells found in CSF. Increases in the amount of leukocytes present can be indicative of infection, stroke, or tumors. Neutrophils will be more abundant in bacterial infections while lymphocytes and monocytes will be more abundant in viral infections and malignancies. The presence of erythrocytes can be indicative of a bleed either in the brain or the spinal cord. However blood can be introduced into a CSF sample as the result of a traumatic tap. It is also important to note that high levels of erythrocytes can falsely increase the concentration of CSF protein. This can occur even when the sample is full of degraded erythrocytes and appears xanthochromic in color.
Cerebral spinal fluid analysis is an important tool available to doctors when diagnosing patients. The brain and spinal cord are well protected by the body; however in the event of illness or injury they can become compromised. It is imperative to perform analysis of samples quickly in order to gain the most accurate picture of a patient’s condition. This valuable analysis allows clinicians to properly treat patients and save lives.
*Turgeon, M. L., Clinical Hematology Theory and Procedures. Boston/Toronto/London: Little, Brown & Company (1993). p. 406.
*Cerebrospinal Fluid. (2008). Chapter Fourteen: Cerebrospinal Fluid. Neuropathology Web. Retrieved on May 29, 2010 from http://www.neuropathologyweb.org/chapter14/chapter14CSF.html
*Cerebral Spinal Fluid Collection. (2010). Cerebral Spinal Fluid Collection. Medline Plus. Retrieved on May 29, 2010 from http://www.nlm.nih.gov/medlineplus/ency/article/003428.htm
Sunday, July 11, 2010
Antibody may help treat and prevent influenza outbreaks
ScienceDaily (2010-07-10) -- Researchers have discovered a monoclonal antibody that is effective against "avian" H5N1, seasonal H1N1 and the 2009 "swine" H1N1 influenza. Scientists have shown that this antibody potently prevents and treats the swine H1N1 influenza in mouse models of the disease. ... > read full article
Saturday, July 3, 2010
Reticulocytes are the most common type of erythrocytes containing inclusions. A reticulocyte is a young erythrocyte that has extruded its nucleus leaving behind reticulum. This is a normal part of the maturation cycle of erythrocytes. This reticulum can appear an even bluish color or a patchy bluish-orange color under a Wright’s stain. This is referred to a polychromatophilia. In order to visualize the inclusions in reticulocytes a peripheral smear can be stained with new methylene blue. Under this stain the inclusions will appear either as filaments or as granules. It is normal for adults to have 0.5 to 1.5% reticulocytes. In general the amount of reticulocytes present is proportional to the production of erythrocytes. In cases of hemorrhage or severe red cell destruction the percentage of reticulocytes present will increase. In the case of chronic anemia or other diseases of defective erythrocyte production the percentage of reticulocytes will be decreased. Reticulocyte counts can be performed manually using new methylene blue stain and counting the cells on a hemocytometer. Most laboratories have instrumentation that will perform this count.
Basophilic stippling, Howell-Jolly bodies, and siderotic granules are common types of erythrocyte inclusions that can be visualized using Wright’s stain. Basophilic stippling is the aggregation of ribosomal material within the erythrocyte. The cell appears basophilic or blue to purple in color, with the presence of dark bluish granules spread throughout the cell. These granules are seen in cases of abnormal heme synthesis and in lead intoxication. Howell-Jolly bodies are composed of nuclear material that has remained inside the erythrocyte after the nucleus has been extruded. The granules are large, round, and are not refractile. These inclusions are very dark in color. Howell-Jolly bodies are usually found in cases of splenectomy and in some hemolytic anemias. They are not usually found in iron-deficiency anemia. Siderotic granules, also known as Pappenheimer bodies, are inclusions that contain iron. These inclusions stain a faint blue color. Siderotic granules are smaller than Howell-Jolly bodies and are usually found in clusters of two or more, often to the side of the cell. These granules are often found after a splenectomy, or whenever hemoglobin synthesis is impaired. They are absent in iron-deficiency anemia. While it is normal to see an occasional Howell-Jolly body in a peripheral smear, the presence of basophilic stippling and siderotic granules is abnormal.
It is important to take note of any type of erythrocytic inclusions when performing a peripheral smear. Each type of inclusion is composed of its own unique cellular material and can be associated with various disease states. While some inclusions may present with similar characteristics closer inspection of the entire peripheral smear can help clarify which inclusions if any are present.
• Miale, J. B., Laboratory Medicine: Hematology. St. Louis, Missouri: The C.V. Mosby Company (1982). p. 486-489.
• Carr, J. H., Rodak, B.F., Clinical Hematology Atlas. St. Louis, Missouri: Elsevier Saunders (2004). p. 111-115.
Friday, July 2, 2010
The nanotube biosensor proved capable of detecting human ferritin, the primary iron-storing protein of cells, and E7 oncoprotein derived from human papillomavirus. Further tests using calmodulin showed the sensor could discriminate between varieties of the protein that take different shapes, according to the multi-disciplinary team of biologists, chemists and physicists.
Molecular imprinting techniques have shown that polymer structures can be used in the development of sensors capable of recognizing certain organic compounds, but recognizing proteins has presented a difficult set of challenges. The BC team used arrays of wire-like nanotubes -- approximately one 300th the size of a human hair -- coated with a non-conducting polymer coating capable of recognizing proteins with subpicogram per liter sensitivity.
Central to the function of the sensor are imprints of the protein molecules within the non-conducting polymer coating. Because the imprints reduce the thickness of the coating, these regions of the polymer register a lower level of impedance than the rest of the polymer insulator when contacted by the charges inherent to the proteins and an ionized saline solution. When a protein molecule drops into its mirror image, it fills the void in the insulator, allowing the nanotubes to register a corresponding change in impedance, signaling the presence of the protein, according to co-author Dong Cai, an associate research professor of Biology at BC.
The detection can be read in real time, instead of after days or weeks of laboratory analysis, meaning the nanotube molecular imprinting technique could pave the way for biosensors capable of detecting human papillomavirus or other viruses weeks sooner than available diagnostic techniques currently allow. As opposed to searching for the HPV antibody or cell-mediated immine responses after initial infection, the nanotube sensor can track the HPV protein directly. In addition, no chemical marker is required by the lebel-free electrochemical detection methods.
"In the case of some diseases, no one can be sure why someone is ill," said Cai. "All that may be known is that it might be a virus. At that time, the patient may not have detectable serum antibodies. So at a time when it is critical to obtain a diagnosis, there may not be any traces of the virus. You've basically lost your chance. Now we can detect surface proteins of the virus itself through molecular imprinting and do the analysis."
In addition to Cai and Professor of Biology Thomas C. Chiles, the Boston College team included Assistant Professor Jeffrey Chuang and researchers Chenjia Xu and Lu Zhang of the Department of Biology; Professor Mary Roberts of the Department of Chemistry; Professor Michael Naughton, Professor Zhifeng Ren and researchers Yucheng Lan, Ying Yu and Hengzhi Wang, and Huaizhou Zhao of the Department of Physics; and researchers Lu Ren, and Ying Yu, also affiliated with the Institute of Nanoscience and Nanotechnology at Central China Normal University.
Reprinted from ScienceDaily @