March 11, 2008, 9:56 PM CT
How digits grow
Researchers at the University of Wisconsin School of Medicine and Public Health (SMPH) are wagging a finger at currently held notions about the way digits are formed.
Studying the embryonic chick foot, the developmental biologists have come up with a model that explains how digits grow and why each digit is different from the others.
As reported in the Proceedings of the National Academy of Sciences Online Early Edition the week of March 10-14, 2008, the scientists found that the development and fate of each digit depends on a surprisingly dynamic process in unanticipated locations and involving unexpected players.
The UW-Madison team showed that growth begins in a portion of the developing digit they have named the phalanx-forming region (PFR). They illustrated that phalanges, structures that later become finger or toe bones, arise not from cartilage cells but from mesenchymal cells. And they discovered that a complex array of signals from a variety of genes at different times combine to form each phalanx.
Though the research was done on chick digits, it may have implications for humans born with a genetic condition known as bradydactyly, or stubby fingers and toes.
The work was undertaken in the laboratory of John Fallon, the Harland Winfield Mossman Professor of Anatomy at the SMPH, who for years has sought to understand how cell fate is determined and patterning-of digits, teeth and feathers-is achieved during embryonic development.........
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March 11, 2008, 7:51 PM CT
New nerve cells originate from neural stem cells
Most cells in the human brain are not nerve cells, but supporting cells (glial cells). They serve as a framework for nerve cells and play an important role in the wound reaction that occurs with injuries to the brain. However, what these reactive glial cells in the brains of mice and men originate from, and which cells they evolve into was hitherto unknown.
Now, the study group of Prof. Dr. Magdalena Gtz is able to show that after injury, these reactive glial cells in the brains of mice restart their cell division. They then become stem cells from which nerve cells can form yet again under favourable cell culture conditions.
With this came the ground-breaking proof that, in an injured region of the brain, adult neural stem cells exist that could later serve as a source of new nerve cells.
In her study group, the stem cell expert, Magdalena Gtz, examines the molecular bases of cerebral development, in particular in the cerebral cortex. Gtz proved in earlier investigations that glial brain cells can act as stem cells, and nerve cells emerge from glial cells. She also pointed out which factors play a role in the cross-over from glial to neural cells. Now, thanks to these results, the distant goal of being able to use the processes therapeutically is getting a little closer stresses Gtz.........
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March 11, 2008, 5:42 AM CT
Recurrent low-grade carcinoma of the ovary less responsive to chemo
Recurrent low-grade serous carcinoma, a rare type of ovary cancer, is less sensitive to chemotherapy and therefore more difficult to treat than more common high-grade ovary cancers, as per scientists from The University of Texas M. D. Anderson Cancer Center. The findings were reported at the Society of Gynecologic Oncologists 39th Annual Meeting on Women's Cancers.
The retrospective study is the first to analyze how women with low-grade tumors respond to chemotherapy in recurrent setting and confirms clinical impressions that the tumors are chemoresistant, said lead author David M. Gershenson, M.D., professor and chair of the Department of Gynecologic Oncology at M. D. Anderson. Prior studies have shown similar tumor resistance in newly diagnosed patients, and there is currently no standard of care for women facing the disease.
The results support a growing body of research that shows low-grade ovarian tumors behave differently than their high-grade counterparts, genetically and clinically. "In order to make meaningful advances in therapy, women with low-grade ovarian tumors must not be grouped together with those with more common ovarian tumors. They require unique consideration and more targeted therapy options for a better chance of survival," Gershenson said.........
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March 11, 2008, 5:40 AM CT
Advanced-stage ovarian cancer patients with BRCA live longe
Two abstracts underscoring the importance of testing for BRCA1/2 mutations in women with ovary cancer were presented at this week's Society of Gynecologic Oncologists 39th Annual Meeting on Women's Cancers, by scientists from The University of Texas M. D. Anderson Cancer Center.
In the first study, a multicenter research team led by M.D. Anderson found advanced- stage ovary cancer patients with non-Ashkenazi Jewish BRCA (non-AJ BRCA) mutations experience longer progression-free and overall survival rates in comparison to those with sporadic ovary cancer. The data confirms prior research which reported that among ovary cancer patients of Ashkenazi-Jewish heritage, BRCA1/2 mutations (AJ BRCA) are associated improved long-term survival.
For this study, scientists examined 85 advanced-stage ovary cancer patients with non-AJ BRCA mutations and 116 patients who did not express any type of BRCA mutation. In comparison to patients without BRCA mutations, non-AJ BRCA carriers had longer progression-free survival of 19.0 vs. 27.8 months and improved overall survival of 65.6 vs. 101.4 months. Non-AJ BRCA patients had a 2.15 times greater odds of complete response to initial chemotherapy response over sporadic, non-carrier patients.
Karen Lu, M.D., associate professor in the Department of Gynecologic Oncology at M. D. Anderson and senior author on the study said the difference in survival rates indicate that individuals with BRCA mutations might respond better to standard chemotherapy for ovary cancer. "Thus, it becomes increasingly valuable to know a patient's BRCA status to guide and personalize therapy decisions," Lu said.........
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March 11, 2008, 5:37 AM CT
Breakthrough Drug for Clot Victims
Washington University scientists have identified the mechanism that makes a bioengineered enzyme function efficiently, opening the way to clinical development of the first safe clot busting agent for treating heart attacks and strokes.
A team of scientists at Oregon Health & Science University and Washington University in St. Louis have described for the first time the mechanism that gives a mutant enzyme molecule that they have engineered - and patented - the potential to become a breakthrough drug for treating heart attacks and strokes.
The team described how their genetically modified enzyme, called WE-thrombin, functions as a potent clot busting agent while retaining little of the power that thrombin, its non-engineered parent, has to cause the opposite result, a cascade of clot building. They did so in a paper published recently in Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB), a peer-evaluated journal of the American Heart Association. An editorial commentary in ATVB hailed this breakthrough as "a significant advance in understanding the functions and antithrombotic potential of (WE thrombin) in particular, and the approach of using engineered human proteins more broadly..".
"The successful development of WE-thrombin would be a major medical breakthrough in antithrombotic treatment, ultimately saving thousands of lives worldwide each year," said the lead investigator András Gruber, M.D., associate professor of biomedical engineering and of medicine in the division of hematology and medical oncology, OHSU School of Medicine.........
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March 11, 2008, 5:32 AM CT
Life expectancy rises for the educated
It's no secret that over the last few decades, life expectancy in the United States has been rising. However, recent data shows that not everyone has benefited from this encouraging trend. New findings from Harvard Medical School and Harvard University demonstrate that individuals with more than 12 years of education have significantly longer life expectancy than those who never went beyond high school.
We like to believe that as we as a country get healthier, everyone benefits, says David Cutler, dean for social sciences at the Faculty of Arts and Sciences at Harvard University, and co-author of study. Here weve observed that you can have a rising tide that only lifts half the boatsand the ones lifted are the ones doing better to begin with.
The research, which was conducted by Cutler and Ellen Meara, assistant professor of health care policy at Harvard Medical School, appears in the March/April edition of the journal Health Affairs.
Over the years, much attention has been paid to mortality rates based on socio-economic status, but less attention has been paid to recent trends in life expectancy, mortality, and education level. To understand recent mortality trends, Meara and Cutler combined death certificate data with census population estimates and data from the National Longitudinal Mortality Study. Restricting analyses to whites and non-Hispanic blacks, the team created two separate data sets, one covering 1981-1988, and the other 1990-2000.........
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March 9, 2008, 6:03 PM CT
Brain network linked to contemplation
A brain network associated with introspective tasks -- such as forming the self-image or understanding the motivations of others -- is less intricate and well-connected in children, researchers at Washington University School of Medicine in St. Louis have learned. They also showed that the network establishes firmer connections between various brain regions as an individual matures.
The researchers are working to establish a picture of how these connections and other brain networks normally develop and interact. They want to use that picture to conduct more detailed assessments of the effects of aging, brain injuries and conditions such as autism on brain function.
"Having this information will not only help us understand what's going wrong in these patients, it will also allow us to better assess whether and how future interventions are providing those patients with effective therapy," says senior author Bradley L. Schlaggar, M.D., Ph.D., associate professor of pediatrics, radiology, neurology and anatomy and neurobiology.
The results appear online this week in The Proceedings of the National Academy of Sciences.
Neuroresearchers including co-author Marcus E. Raichle, M.D., professor of radiology, of anatomy and neurobiology and of neurology first identified the network, which is called the default network, in 1996. Since then, researchers have linked it to many inward-looking activities, including the creation of the "autobiographical self," a person's internal narrative of their life story; and "mentalizing," the ability to analyze the mental states of others and use those insights to adjust the self's behavior appropriately.........
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March 9, 2008, 6:00 PM CT
MRI-PET Scanner Combo
In this combined PET/MRI scan of a tumor in a lab mouse, the colored area is the PET scan image. The arrow points to a hole, probably dying tissue, in the middle of the tumor. (Courtesy photo)
Two kinds of body imaging -- positron emission tomography (PET) and magnetic resonance imaging (MRI) -- have been combined for the first time in a single scanner.
MRI scans provide exquisite structural detail but little functional information, while PET scans -- which follow a radioactive tracer in the body -- can show body processes but not structures, said Simon Cherry, professor and chair of biomedical engineering at UC Davis. Cherry's lab built the scanner for studies with laboratory mice, for example in cancer research.
"We can correlate the structure of a tumor by MRI with the functional information from PET, and understand what's happening inside a tumor," Cherry said.
Combining the two types of scan in a single machine is difficult because the two systems interfere with each other. MRI scanners rely on very strong, very smooth magnetic fields that can easily be disturbed by metallic objects inside the scanner. At the same time, those magnetic fields can seriously affect the detectors and electronics needed for PET scanning. There is also a limited amount of space within the scanner in which to fit everything together, Cherry noted.
Scanners that combine computer-assisted tomography (CAT) and PET scans are already available, but Computerized axial tomography scans provide less structural detail than MRI scans, particularly of soft tissue, Cherry said. They also give the patient a dose of radiation from X-rays.........
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March 9, 2008, 5:52 PM CT
Allergic Response Tied to Lipid Molecules
A team of Penn State University scientists is the first to demonstrate that lipid molecules in cell membranes participate in mammals' reactions to allergens in a living cell. The finding will help researchers better understand how allergy symptoms are triggered, and could contribute to the creation of improved drugs to treat them. The work would be published in the 14 recent issue of the Journal of Biological Chemistry.
The team studied clusters of cholesterol-rich lipid molecules that they believe serve as platforms for the receptors that receive antibodies, the proteins that protect the body from allergens. In this case, the team examined IgE antibodies, which upon binding to their receptors initiate a cell's release of histamine--the substance that causes the unpleasant, but beneficial, mucous production, congestion, and itchiness linked to allergies. "This research is basically the molecular foundation for why a number of people sneeze in the spring," said Ahmed Heikal, an associate professor in the Department of Bioengineering and a leader of the project.
While the idea that lipid clusters--also known as lipid domains--are involved in the allergic response is not new, the Penn State team is the first to document this connection in a living cell under physiological conditions. "No one has observed the domains in action because they are too small and too transient--held together by very weak molecular interactions--to be viewed with a light microscope," said Erin Sheets, a Penn State assistant professor of chemistry who also is a leader of the project. "To overcome this challenge," added Heikal, "we used a combination of imaging and spectroscopy techniques that we are in the process of developing in our laboratories.........
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March 9, 2008, 5:08 PM CT
Profound Impact Of Our Unconscious On Reaching Goals
Whether you are a habitual list maker, or you prefer to keep your tasks in your head, everyone pursues their goals in this ever changing, chaotic environment. We are often aware of our conscious decisions that bring us closer to reaching our goals, however to what extent can we count on our unconscious processes to pilot us toward our destined future?
People can learn rather complex structures of the environment and do so implicitly, or without intention. Could this unconscious learning be better if we really wanted it to?.
Hebrew University psychology experts, Baruch Eitam, Ran Hassin and Yaacov Schul, examined the benefit of non-conscious goal pursuit (moving toward a desired goal without being aware of doing so) in new environments. Existing theory suggests that non-conscious goal pursuit only reproduces formerly learned actions, therefore ineffective in mastering a new skill. Eitam and his colleagues argue the opposite: that non-conscious goal pursuit can help people achieve their goals, even in a new environment, in which they have no previous experience.
In the first of two experiments, Eitam and his colleagues had participants complete a word search task. One half of the participants' puzzles included words linked to achievement (e.g. strive, succeed, first, and win), while the other half performed a motivationally neutral puzzle including words such as, carpet, diamond and hat. Then participants performed a computerized simulation of running a sugar factory. Their goal in the simulation was to produce a specific amount of sugar. They were only told that they could change the number of employees in the factory. Eventhough participants were not told about the complex relationship that existed between the number of employees and past production levels (and could not verbalize it after the experiment had ended); they gradually grew better in controlling the factory.........
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