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(Anatomy) Blood: Super-stretchy Blood Clot Fibers

 
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PostPosted: Sat Aug 12, 2006 7:33 am    Post subject: (Anatomy) Blood: Super-stretchy Blood Clot Fibers Reply with quote






American Association for the Advancement of Science
3 August 2006

Super-stretchy blood clot fibers

Even though blood is a liquid, when you cut yourself, something amazing happens. Special proteins in your blood link together in chains, forming solid fibers that work their way into a net. This net catches red blood cells, and, voila, you have a blood clot that stops the bleeding.

Without blood clotting, even simple cuts could become dangerous. Researchers would like to use artificial models of blood clots in order to better understand how they behave. These models might help scientists better understand bleeding and clotting disorders.

But, we still don't know very much about the fibers that make up the blood clot's webby matrix.

Wenhua Liu of Wake Forest University and his colleagues have discovered that the fibers are surprisingly stretchy, even more than your average rubber-band. They can stretch nearly three times their length without losing their stretchiness and up to six times their length before breaking.

When the fibers are tangled into a web, as they do for blood clotting, the web is still pretty stretchy, but not nearly as much as the individual fibers, the researchers found.

This study appears in the 4 August 2006 issue of the journal Science.

*************************************************************

Questions to explore further this topic:

What is blood?

http://library.thinkquest.org/5777/cir4.htm
http://www.mybloodyourblood.org/biology.htm
http://www.donateblood.com.au/.....sblood.asp
http://www.fi.edu/biosci/blood/blood.html
http://learn.genetics.utah.edu...../blood.cfm
http://www.lpch.org/diseaseHea.....oview.html
http://vilenski.org/science/hu.....nesys.html

Red Gold: The Epic Story of Blood

http://www.pbs.org/wnet/redgold/

Red blood cells

http://www.fi.edu/biosci/blood/red.html

White blood cells

http://www.fi.edu/biosci/blood/white.html

Blood plasma

http://www.fi.edu/biosci/blood/plasma.html

Platelets

http://www.fi.edu/biosci/blood/platelet.html

What is blood clotting?

http://web.indstate.edu/thcme/.....ation.html
http://www.hhmi.org/research/i.....sburg.html
http://en.wikipedia.org/wiki/Coagulation
http://discoverysedge.mayo.edu/vascular_biology/

What is fibrin?

http://www.cs.unc.edu/Research.....index.html

What is thrombus?

http://www.nlm.nih.gov/medline.....001124.htm

What is a blood thinner?

http://www.wisegeek.com/what-is-blood-thinner.htm

What are blood types?

http://www.fi.edu/biosci/blood/types.html
http://learn.genetics.utah.edu...../types.cfm

What is the Rhesus (Rh) factor?

http://www.fi.edu/biosci/blood/rh.html

What are blood transfusions?

http://learn.genetics.utah.edu.....usions.cfm

What is it like to donate blood?

http://www.unitedbloodservices.....tlike.html

What is blood pressure?

http://www.lifeclinic.com/focus/blood/whatisit.asp
http://www.nhlbi.nih.gov/hbp/bp/bp.htm

What is high blood pressure?

http://www.nhlbi.nih.gov/healt.....hatIs.html
http://www.americanheart.org/p.....ifier=2112

What are blood diseases?


GAMES

http://vilenski.org/science/hu....._game.html
http://www.givelife2.org/games/memory.asp
http://www.givelife2.org/games/matchgame.asp
http://www.givelife2.org/games/bloodiq.asp
http://www.givelife2.org/games/trivia.asp
http://www.givelife2.org/games/donortag.asp


Last edited by adedios on Sat Jan 27, 2007 4:36 pm; edited 2 times in total
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PostPosted: Mon Nov 06, 2006 11:23 am    Post subject: New Insight into How Blood Clots Reply with quote

New Insight into How Blood Clots

By Corey Binns
Special to LiveScience
posted: 06 November 2006
09:08 am ET

When you slice your finger while chopping celery, it requires more than 80 different chemical reactions to clot blood and stop the bleeding. But one false reaction, and the clot could form in the wrong spot and be deadly.

Clots sometimes form even when there's no wound to plug, and for years, scientists didn't understand the process or know how to tell when it might happen. Now researchers at the University of Chicago have developed a simple technique to predict the timing and location of blood clots.

"The really cool part was that our observations were actually predicted by an artificial model of clotting that represented the 80 reactions of clotting in just three simple chemical reactions," said Christian Kastrup, a University of Chicago chemistry graduate student and study coauthor.

For the full article:

http://www.livescience.com/hum.....clots.html
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PostPosted: Tue Jan 30, 2007 7:16 am    Post subject: Important mechanism identified in the formation of blood ves Reply with quote

Karolinska Institutet
29 January 2007

Important mechanism identified in the formation of blood vessels

All tissues, sick and healthy alike, need a blood supply to survive and grow. The key to many medical problems, like preventing tumour development, is therefore to obstruct the spread of the blood vessels. Research scientists at Karolinska Institutet have now discovered a heretofore unknown mechanism for how the body links together its blood vessels.

New blood vessels are formed when a "shoot" sprouts from an already existing vessel. These shoots lengthen, branch off and contact other vessels as they form communicating networks of channels. The process is called "angiogenesis" and is important in foetal development and normal tissue formation in connection with the healing of wounds, the menstrual cycle and so on. However, it also plays a critical part in morbid tissue formation, such as cancer and chronic inflammatory diseases.

The inhibition of morbid angiogenesis therefore has very attractive therapeutic potential for a variety of diseases. Tumours, for instance, can grow no larger than 1 or 2 mm without new blood vessels, upon which they are dependent for their proliferation. To date, anti-angiogenic therapy has proved effective in the treatment of colon cancer and the common eye disease AMD (Age-dependent Macula Degeneration).

All therapies have so far targeted the growth factor VEGF (Vascular Endothelial Growth Factor). VEGF controls several important functions during the formation of blood vessels by signalling via receptors on the surface of the endothelial cells, the specialised layer of cells on the interior surface of the blood vessels.

Swedish scientists at Karolinska Institutet and the biotech company AngioGenetics AB have now shown that another factor called Dll4 (Delta-like 4) has a similarly fundamental role in blood vessel formation as VEGF. The results are published in Nature no. 28 (January 2007) and can mean that Dll4 is just as important a target for anti-angiogenic drugs as VEGF.

"We can now develop ways of boosting the effect of existing anti-angiogenic therapies, and maybe we can even start to treat tumour types that do not currently respond to anti-angiogenic drugs," says Mats Hellström, one of the scientists involved in the study.

The researchers have found that Dll4 signalling determines how many sprouts bud off from the parent vessel. This principle is critical to the number of branches and links that form and to attaining the correct density of vessels. Too great a blood supply to a tissue is just as devastating as too little.

###
Karolinska Institutet is one of the leading medical universities in Europe. Through research, education and information, Karolinska Institutet contributes to improving human health. Each year, the Nobel Assembly at Karolinska Institutet awards the Nobel Prize in Physiology or Medicine. For more information, visit ki.se

Publication:
"Dll4 signalling through Notchi regulates formation of tip cells during angiogenesis"
Nature, 28 January 2007, DOI; 10.1038/nature05571

Download the abstract at http://dx.doi.org/

For further information, please contact:

Dr. Mats Hellström
Department of Medical Biochemistry and Biophysics
Tel: +46 (0)8 524 879 55 or +46 (0)70 871 70 01
Mats.hellström@ki.se
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PostPosted: Wed Feb 07, 2007 10:45 am    Post subject: Better Assessment of Transfusions Could Save Blood Reply with quote

Better Assessment of Transfusions Could Save Blood
Blackwell Publishing


Lebanon, N.H. – February 06, 2007 – Nearly 95 percent of patients admitted to hospital intensive care units are affected by anemia. Consequently, these patients receive a large number of red blood cell (RBC) transfusions in order to restore proper hemoglobin levels. New research shows that alternative treatments may lead to fewer transfusions, conserving critical blood supplies in hospitals. The report is published in Seminars in Dialysis.


Phlebotomy, the removing of blood from the body, has been seen as a major factor contributing to anemia, but recent research shows that it may not be the primary cause. “There is now ample evidence suggesting that the anemia observed in the critically ill is an underproduction anemia, consistent with what is commonly referred to as the anemia of chronic inflammatory disease,” says Howard L. Corwin, M.D., author of the report.


The expected benefit of RBC transfusions is an increased oxygen level, which prevents cellular injury. However, studies have not consistently demonstrated that the increased hemoglobin level with transfusion leads to improved tissue oxygenation. At this point in time, there are no convincing data to support the routine use of RBC transfusion to treat anemia in hemodynamically stable, critically ill patients without evidence of acute bleeding.
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PostPosted: Tue Mar 13, 2007 7:11 am    Post subject: Blood Cells Change Shape to Fit Through Tiny Vessels Reply with quote

Blood Cells Change Shape to Fit Through Tiny Vessels

By Andrea Thompson
LiveScience Staff
posted: 12 March, 2006
5:15 pm ET

Human red blood cells rushing through the body to carry oxygen and carbon dioxide to and from the organs are forced to squeeze through smaller and smaller blood vessels. A new study has discovered how exactly the teeny hat-shaped cells deform themselves to fit through these micro-tunnels.

The research could help scientists better understand certain blood disorders like malaria and sickle cell anemia.

Blood cells must squeeze through the body’s smallest blood vessels, called capillaries, to do their job, but capillaries often become narrower than the cells in their normal disc shape. So the cells must deform to fit through them.

For the full article:

http://www.livescience.com/hum.....blood.html
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PostPosted: Tue Mar 27, 2007 7:54 am    Post subject: New Blood Thinner May Work Without Bleeding Risk Reply with quote

New Blood Thinner May Work Without Bleeding Risk
University of Kentucky

LEXINGTON, Ky. (March 26, 2007) − When studying a new blood thinner, one of the first signs the drug is working is seeing a slight increase in minor bleeding—nose bleeds and bruising, an inconvenient side effect of preventing the blood clots that are the leading cause of heart attack and stroke. While potentially life-saving, the drugs can also pose a risk of major bleeding in some patients, requiring frequent monitoring of blood levels.

So when he didn’t see any significant increase in those typical bleeding events when studying a new blood thinner last year, UK College of Medicine cardiovascular chief David Moliterno was surprised when, at the close of the study in September, the results showed promise of significantly reducing the risk of heart attack and death with no statistical increase in major and minor bleeding events.

The drug, called a thrombin-receptor antagonist, or TRA, works in a unique way to prevent clotting by breaking down the communication between cells and proteins involved in forming clots. TRA, which is manufactured by Schering-Plough Corporation, was given in addition to established anti-clotting drugs to 1,030 patients undergoing cardiac catheterization and related intervention at 77 sites in six countries (including the United States, Canada, Italy, Belgium, Netherlands and Germany). The University of Kentucky enrolled 32 patients between August 2005 and September 2006. Patient follow-up was completed in January 2007.

“We were surprised by the extent of benefit,” Moliterno said. “These results are so noteworthy because the study demonstrated that this first-in-class TRA did not increase bleeding at all in a group of patients that is certainly at risk. And honestly, therefore, we did not expect to see a large benefit. While further study is required, we observed a 46 percent lowering in serious cardiovascular events, mainly a reduction in heart attacks. This represents an early and strong efficacy signal for this novel antiplatelet compound. This is encouraging, particularly in light of the fact that this patient population requires advanced therapies and is difficult to treat.”

Moliterno presented the study findings to thousands of cardiologists Saturday at the opening of the American College of Cardiology’s annual scientific sessions, taking place this year in New Orleans. Moliterno and other UK Linda and Jack Gill Heart Institute cardiologists will be giving a record 26 presentations, including 10 original research study releases, at the week-long ACC scientific sessions and Innovation in Intervention: i2 Summit 2007.
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PostPosted: Tue Apr 03, 2007 8:18 pm    Post subject: Transfusion expert urges wider use of filtered blood Reply with quote

University of Rochester Medical Center
3 April 2007

Transfusion expert urges wider use of filtered blood

Leukoreduction is better for patients, University of Rochester study concludes
Filtering white cells from donor blood before a transfusion is much safer for patients and long overdue as a national standard for all surgical procedures, according to University of Rochester researchers who present their analysis in the April journal, Transfusion.

The practice of removing the white cells from blood is called leukoreduction. But despite the recommendations of two national advisory committees in 10 years that voted in favor of all patients in the United States receiving leukoreduced blood, ("universal leukoreduction"), the practice is still not wholly supported in the medical community, nor recommended by the Food and Drug Administration. Part of the reason is fear of increased cost.

However, Neil Blumberg, M.D., lead author of the study and a proponent of leukoreduction, argues that several cost-benefit analyses show that an upfront increase of $25 to $35 for each unit of filtered blood is offset by savings from less use of antibiotics, reduced patient time in the ICU, and shorter lengths of hospital stays overall. One study, in fact, estimated that the savings in treating heart surgery complications alone could total $1 billion a year, nationwide.

"Rarely do we come up with a medical advance that saves money and is better for patients at the same time. This is as basic as washing your hands before conducting a physical examination of a patient," Blumberg said. "But despite much scientific evidence that supports this notion, millions of people today are still receiving transfusions that might needlessly be harmful to them. The single most effective and overdue safety measure the FDA could take at this time is to mandate leukoreduction of all transfusions through its regulatory power."

Blumberg's group reviewed approximately 520 abstracts and nine published randomized clinical trials, on the risks and benefits of using leukoreduced blood. They assessed the statistical methods that were used in each study, and found what they believed to be flawed data in some cases. The chief problem, Blumberg's group discovered, was that some studies included hundreds of patients who never received blood transfusions. These patients would have been irrelevant to a study assessing the risks and/or benefits of certain types of transfusions, because they couldn't have benefited nor could they have been harmed by a transfusion. Furthermore, some studies used data that did not reflect actual investigative results, Blumberg said.

When the data was restricted to patients receiving transfusions, researchers found that post-surgical infection rates dropped from 33 percent to 23 percent. In other words, the relative risk of infection dropped by about 30 percent for the patients with leukoreduced blood.

"Our data would suggest that when you combine all of the safety measures that have been made to the blood supply since the AIDS epidemic, all of those safety adjustments combined are is still less beneficial to patients than the benefits of leukocyte reduction," Blumberg said.

Transfusions are done routinely, and some practitioners are not convinced they hold many risks. But doctors at the University of Rochester, leaders for two decades in the study of "transfusion immunomodulation," believe otherwise. Giving donor blood to someone, Blumberg said, is akin to a temporary organ transplant. In many cases the transfused blood modifies a person's immune system – either in a favorable or unfavorable way – by interacting with the patient's own white cells.

Removing the foreign white cells from transfused blood reduces the chances of a negative reaction by the host immune system. In 1998 the University's Strong Memorial Hospital was among the first hospitals in the country to begin using leukoreduced blood for all cardiac surgery cases. Since then, the hospital has extended its leukoreduction practice to all patients, beginning in 2000.


###
Blumberg is a professor of Pathology and Laboratory Medicine and director of Transfusion Medicine/Blood Bank, at the University of Rochester, and director of clinical laboratories at Strong Memorial Hospital. The University funded this project. Co-authors are: Gary Lyman, M.D., and Joanna Heal, M.D., of the Hematology-Oncology Unit of the UR Department of Medicine and Drs. Hongwei Zhao, Hongkun Wang and Susan Messing of the UR Department of Biostatistics and Computational Biology.
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PostPosted: Mon Jul 16, 2007 11:51 am    Post subject: Red blood cells “talk” to platelets, with implications for d Reply with quote

Red blood cells “talk” to platelets, with implications for diabetes
Analytical Chemistry
16 July 2007

Amid growing indications that the traditional image of red blood cells (RBCs) falls short of reality, chemists are reporting evidence that RBCs are key participants in a communication system among cells in the bloodstream. Messaging between RBCs and platelets (blood components that cause clotting) they say, could explain the effects of a drug suggested for use in preventing heart attacks and other complications of diabetes.

In a study scheduled for the July 13 issue of ACS’ Analytical Chemistry, a semi-monthly journal, Dana Spence and colleagues note that RBCs once were regarded mainly as oxygen carriers. Recent research, however, shows that red cells also release ATP, a molecule that is the source of energy for all life processes, as they deform while they travel through small blood vessels.

By observing blood flow through artificial blood vessels in laboratory experiments, Spence’s group now has established that the ATP signals blood platelets to produce nitric oxide (NO). That messenger molecule has a variety of functions, including dilating blood vessels. When released from platelets, NO helps regulate platelets’ activity, preventing excessive clotting. Disruption of the RBC-platelet communications system may play a role in diabetic complications such as heart disease and strokes, the researchers said. The new study also found that Trental, reported to have beneficial effects in preventing certain diabetic complications, may work by boosting ATP release from red blood cells.

ARTICLE #1 FOR IMMEDIATE RELEASE
“Red Blood Cell Stimulation of Platelet Nitric Oxide Production Indicated by Quantitative Monitoring of the Communication between Cells in the Bloodstream”

DOWNLOAD PDF http://pubs.acs.org/cgi-bin/sa.....706271.pdf
DOWNLOAD HTML http://pubs.acs.org/cgi-bin/sa.....06271.html
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PostPosted: Tue Oct 16, 2007 1:36 pm    Post subject: MIT: blood may help us think Reply with quote

Massachusetts Institute of Technology
16 October 2007

MIT: blood may help us think

CAMBRIDGE, Mass.--MIT scientists propose that blood may help us think, in addition to its well-known role as the conveyor of fuel and oxygen to brain cells.

“We hypothesize that blood actively modulates how neurons process information,” explains Christopher Moore, a principle investigator in the McGovern Institute for Brain Research at MIT, in an invited review in the Journal of Neurophysiology. “Many lines of evidence suggest that blood does something more interesting than just delivering supplies. If it does modulate how neurons relay signals, that changes how we think the brain works.”

According to Moore's Hemo-Neural Hypothesis, blood is not just a physiological support system but actually helps control brain activity. Specifically, localized changes in blood flow affect the activity of nearby neurons, changing how they transmit signals to each other and hence regulating information flow throughout the brain. Ongoing studies in Moore's laboratory support this view, showing that blood flow does modulate individual neurons.

Moore's theory has implications for understanding brain diseases such as Alzheimer's, schizophrenia, multiple sclerosis and epilepsy. “Many neurological and psychiatric diseases have associated changes in the vasculature,” says Moore, who is also an assistant professor in MIT's Department of Brain and Cognitive Sciences.

“Most people assume the symptoms of these diseases are a secondary consequence of damage to the neurons. But we propose that they may also be a causative factor in the disease process, and that insight suggests entirely new treatments.” For example, in epilepsy people often have abnormal blood vessels in the brain region where the seizures occur, and the hypothesis suggests this abnormal flow may induce epileptic onset. If so, drugs that affect blood flow may provide an alternative to current therapies.

The hypothesis also has important implications for functional magnetic resonance imaging, or fMRI, a widely used brain scanning method that indicates local changes in blood flow. “Scientists looking at fMRI currently regard blood flow and volume changes as a secondary process that only provides read-out of neural activity,” explains Rosa Cao, a graduate student in Moore's lab and co-author of the paper. “If blood flow shapes neural activity and behavior, then fMRI is actually imaging a key contributor to information processing.”

Again, studies in Moore's lab support this interpretation. For example, his fMRI studies of the sensory homunculus - the brain's detailed map of body parts like fingers, toes, arms, and legs- show that when more blood flows to the area representing the fingertip, people more readily perceive a light tap on the finger. This suggests that blood affects the function of this brain region and that information about blood flow can predict future brain activity. This finding does not undermine prior studies, but adds another, richer layer to their interpretation and makes fMRI an even more useful tool than it already is.

How could blood flow affect brain activity? Blood contains diffusible factors that could leak out of vessels to affect neural activity, and changes to blood volume could affect the concentration of these factors. Also, neurons and support cells called glia may react to the mechanical forces of blood vessels expanding and contracting. In addition, blood influences the temperature of brain tissue, which affects neural activity.

To Moore's knowledge, the Hemo-Neural Hypothesis offers an entirely new way of looking at the brain. “No one ever includes blood flow in models of information processing in the brain,” he asserts. One historical exception is the philosopher Aristotle, who thought the circulatory system was responsible for thoughts and emotions. Perhaps the ancient Greeks were on to something.


###
This work was funded by Thomas F. Peterson, the Mitsui Foundation and the McGovern Institute for Brain Research at MIT.

Written by Cathryn M. Delude, McGovern Institute for Brain Research at MIT
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PostPosted: Tue Oct 30, 2007 12:52 pm    Post subject: Elevated nitric oxide in blood is key to high altitude funct Reply with quote

Case Western Reserve University
30 October 2007

Elevated nitric oxide in blood is key to high altitude function for Tibetans

CLEVELAND—How can some people live at high altitudes and thrive while others struggle to obtain enough oxygen to function?

The answer for Tibetans who live at altitudes around 14,000 feet is increased nitric oxide (NO) levels. High levels of NO circulate in various forms in the blood and produce the physiological mechanisms that cause the increased blood flow that maintains oxygen delivery despite hypoxia—low levels of oxygen in the ambient air and the bloodstream. Researchers from Case Western Reserve University and the Cleveland Clinic report that Tibetans have 10 times more NO and have more than double the forearm blood flow of low-altitude dwellers. The findings from a comparison of NO levels in the high and low altitude dwellers are reported in the article, “Higher Blood Flow and Circulating NO Products Offset High-altitude Hypoxia among Tibetans,” in the current Proceedings of the National Academy of Sciences (PNAS).

The low barometric pressure of high altitudes generally causes low arterial oxygen content among Tibetans, yet the researchers have found that Tibetans consume oxygen at normal rates.

“We asked how that could be done,” said Cynthia Beall, the S. Idell Pyle Professor of Anthropology at Case Western Reserve University. For two decades, Beall has been one of the world’s leading researchers in the studies of high altitude adaptation in different populations in Ethiopia, South America and Tibet.

Beall collected blood samples and blood flow readings from the forearms of 88 Tibetans during a 2002 research trip that was funded by the National Science Foundation. The blood flow data and blood samples were brought back to the United States where Serpil Erzurum, chair of pathobiology, Cleveland Clinic, and the paper’s lead author, analyzed the information. In Erzurum’s lab, Allison Janocha, a Case Western Reserve graduate, performed many of the technically challenging analyses.

For comparison, the scientists collected the same information from 50 near sea-level dwellers from the United States who participated in the study at the General Clinical Research Center at the Cleveland Clinic.

The combined increase in NO and blood flow levels resulted in double the amount of oxygen delivered to the capillary beds in the Tibetans’ arms.

The researchers hypothesize that Tibetans have a genetic mutation that allows high NO production. Genetic studies and comparable data on sea-level populations living at high altitude would be needed to test that hypothesis, said Beall.

During the study, the researchers also recognized another population difference: Tibetan women were found to have higher nitrite and lower nitrate levels than those of Tibetan men, whereas no gender differences were found in sea-level dwellers.

In this research, blood flow is determined by the length, number and width of the diameter of blood vessels. These numbers are determined partly by NO, which is a dilator of the vessels and prevents high blood pressure, which would result from increased blood flow in restricted blood vessels. NO also helps in the release of oxygen to tissues. NO reacts in the blood to produce nitrite, nitrate, nitrosothiol proteins and á-nitrosyl hemoglobin, which can be used as indicators of NO production. To confirm the increases in NO, the researchers subjected the Tibetan samples to sensitive high performance liquid chromatography, where the results verified the 10-fold increase of NO in the blood.

This study continues to unravel the mysteries of high altitude adaption and follows Beall’s 2001 study, published in Nature, on the NO levels in exhaled breath of Tibetans, which were found to be 25 percent greater than that of local Cleveland residents. There was also a related paper on NO and pulmonary blood flow in 2005 in the Journal of Applied Physiology. Brian Hoit of the department of medicine at the Case Western Reserve School of Medicine was the lead author on that paper.


###
Researchers on the most recent study include Sudhakshina Ghosh, Allison Janocha, Weilin Xu, Dennis Stuehr, and Jesus Tejero from the CCF department of pathobiology; and Selena Bauer, Martin Feelisch, and Nathan Bryan from the Whitaker Cardiovascular Institute in Boston University School of Medicine; and Craig Hemann and Russ Hille from Ohio State University
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PostPosted: Tue Nov 06, 2007 6:18 pm    Post subject: Hemoglobin uncovered Reply with quote

IRB Barcelona News
6 November 2007

Hemoglobin uncovered

Researchers at the BSC and the IRB Barcelona unveil crucial information about the protein transporter of oxygen, which opens up the possibility to optimize its function by introducing modifications. The study is published in the scientific journal Proceedings of the National Academy of Sciences.

For the full article:

http://www.irbbarcelona.org/in.....escubierto
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PostPosted: Wed Dec 12, 2007 3:39 pm    Post subject: Stanford researchers identify granddaddy of human blood cell Reply with quote

Stanford University Medical Center
12 December 2007

Stanford researchers identify granddaddy of human blood cells

STANFORD, Calif. - Researchers at the Stanford University School of Medicine have isolated a human blood cell that represents the great-grandparent of all the cells of the blood, a finding that could lead to new treatments for blood cancers and other blood diseases.

This cell, called the multipotent progenitor, is the first offspring of the much-studied blood-forming stem cell that resides in the bone marrow and gives rise to all cells of the blood. It's also the cell that's thought to give rise to acute myelogenous leukemia when mutated.

Isolating this cell, which is well known in mice but had yet to be isolated in human blood, fills in an important gap in the human blood cell family tree. The work will be published in the Dec. 13 issue of the journal Cell Stem Cell.

Irving Weissman, MD, director of Stanford's Institute for Stem Cell Biology and Regenerative Medicine, spent his early career identifying each cell in the mouse blood family tree. The progression went from the stem cell through the progenitor cell through progressively more specialized cells, ending up with the red blood cells, platelets and immune cells that make up the bulk of the blood.

This detailed information has helped researchers understand the origins of blood diseases and cancers and has led to advances in bone marrow transplantation. But studies in mice are never a perfect substitute for understanding those same cells in humans, said Ravindra Majeti, MD, PhD, an instructor in hematology and co-lead author of the paper.

Majeti isolated the human progenitor cell by grouping human blood cells according to proteins on their cell surface. He and co-lead author Christopher Park, MD, PhD, an instructor in pathology, then looked for a pool of cells that could form all the final cells of the blood, but lacked the ability to constantly renew their own supplies - a trait that is unique to the stem cell. Those characteristics are what distinguish the mouse progenitor cell, and, they thought, would likely be shared by the human equivalent.

One pool of cells fulfilled those requirements. Knowing the proteins on the surface of that cell, researchers can now reliably identify, isolate and study the cell in the lab.

Being able to isolate and study this cell has many implications for human disease, according to Majeti. First, this progenitor cell is also thought to be the cell that, after a number of mutations, eventually becomes the acute myelogenous leukemia stem cell. That's the cell that lies at the heart of the leukemia and that must be destroyed in order to cure the disease.

"We can compare the leukemic stem cell to this progenitor cell and from that find out what makes the leukemic stem cell different," Weissman said. That difference could very well be a target for leukemia treatments.

Another use for this cell could be in bone marrow transplantation, according to Majeti. Having the human progenitor cell means researchers can then produce all the cells of the blood in a lab dish. They can then take their pick of which cells would be most beneficial for possible transplantation.


###
The work was funded by the Walter and Idun Y. Berry Foundation and by the National Institutes of Health.
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PostPosted: Mon Mar 31, 2008 2:41 pm    Post subject: Blood Goes Stale—and Fairly Quickly Reply with quote

Blood Goes Stale—and Fairly Quickly
Cynthia Graber

April 2, 2008

After an accident, an ambulance arrives and rushes a patient to the hospital. Doctors realize the patient has lost too much blood and needs a donation of stored blood, called a transfusion. That blood comes from people who have voluntarily donated their own for emergencies or surgeries, so it's ready when needed.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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