Source: http://www.thehollywoodgossip.com/2013/05/jennifer-hudson-confirmed-as-new-american-idol-judge/
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Saturday, May 25, 2013
Detecting mirror molecules
Thursday, May 23, 2013
Harvard physicists have developed a novel technique that can detect molecular variants in chemical mixtures ? greatly simplifying a process that is one of the most important, though time-consuming, processes in analytical chemistry.
As described in a paper in Nature, post-doctoral researcher David Patterson, Professor of Physics John Doyle and Dr. Melanie Schnell of the Center for Free-Electron Laser Science (CFEL) in Hamburg, Germany developed a system that relies on finely-tuned microwave fields to identify molecular variants apart, and to determine how much variant is in a mixture.
The ability to tell such variants apart, researchers said, is critical because many chemical compounds exist in two forms, each of which is a mirror image of the other. Such molecules are called chiral, from the ancient Greek for hand, and are often described as being either "right-handed" or "left-handed."
Knowing whether a molecule is right- or left-handed, scientists say, is important, because each type of molecule behaves differently in chemical reactions. Much of biology, for example, is predicated on the idea that amino acids are "left-handed," while sugar molecules are "right-handed."
"The 'wrong' sort of a compound can function completely differently in an organism," explains Schnell, who leads an independent Max Planck research group for structure and dynamics of molecules at CFEL. "In the best case it is just ineffective. In the worst case it is toxic."
The challenge, however, is that telling the two variants of a chiral molecule apart is no easy job.
A common way to discern between them is to shine linear polarised light through them. While one variant will turn the plane of polarisation to the left, the other will turn it to the right. The problem with that method, researchers say, is that it produces rather weak effects, and can only be used on liquid samples, and it can be difficult to use on samples that contain a mixture of many different species.
"It's an extremely common situation to have a mixture ? say a blood sample, or something from a complex chemical process - that contains a left-handed version of some compounds and a right handed version others ? for example, left handed alanine along with right handed citric acid. Optical polarimetery really struggles with such a situation ? if there's more than about 3 compounds, it's pretty hopeless. We hope our technique will provide a tool which can produce a complete analysis of such a mixture".
In contrast, the method developed by Patterson, Doyle and Schnell, by comparison, relies on what is called the electric dipole moment of each molecule, or the way each interacts with an external electric field. As a consequence of their mirror-image construction, molecules rotate in opposite directions when certain microwave fields are applied ? and this results in a signature which tells if the molecules are left or right handed.
To measure the dipole moment of molecules, the team used microwaves.
Researchers fed a gaseous sample into a chamber, then cooled it to -226 degrees Celsius. As the cold gas interacted with a precisely-tuned microwave fieldwhich caused the molecules to spin and give off their own microwave radiation. By monitoring those emissions, researchers are able to tell whether the molecules are right- or left-handed.
The researchers tested their method using the organic compound 1,2-propanediol, and were able to reliably differentiate between the two variants, but also determine the ratio of variants in a mixture by finely-tuning the microwave frequency.
"We can soon measure mixtures of different compounds and determine the enantiomer ratios of each," explains Schnell. In a next step the researchers plan to apply the technique in a broadband spectrometer at CFEL that could then measure the ratios in other mixtures of substances.
In the longer run, the method opens the exciting perspective to develop a technique for separating variants ? a technique that, if successful, could be of great interest to a number of industries, particularly the development of new pharmaceuticals.
###
Harvard University: http://www.harvard.edu
Thanks to Harvard University for this article.
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Source: http://www.labspaces.net/128368/Detecting_mirror_molecules
Obama OKs honor for Birmingham bombing victims
President Barack Obama signs a bill designating the Congressional Gold Medal commemorating the lives of the four young girls killed in the 16th Street Baptist Church Bombing of 1963, Friday, May 24, 2013, in the Oval Office of the White House in Washington. From left are, Rep. Terri Sewell, D-Ala. sponsor of the bill; Lisa McNair; Thelma "Maxine" Pippen McNair mother of Denise McNair; Dianne Braddock sister of Carole Robertson; and Rev. Arthur Price Jr., pastor of the Sixteenth Street Baptist Church. (AP Photo/Jacquelyn Martin)
President Barack Obama signs a bill designating the Congressional Gold Medal commemorating the lives of the four young girls killed in the 16th Street Baptist Church Bombing of 1963, Friday, May 24, 2013, in the Oval Office of the White House in Washington. From left are, Rep. Terri Sewell, D-Ala. sponsor of the bill; Lisa McNair; Thelma "Maxine" Pippen McNair mother of Denise McNair; Dianne Braddock sister of Carole Robertson; and Rev. Arthur Price Jr., pastor of the Sixteenth Street Baptist Church. (AP Photo/Jacquelyn Martin)
President Barack Obama signs a bill designating the Congressional Gold Medal commemorating the lives of the four young girls killed in the 16th Street Baptist Church Bombing of 1963, Friday, May 24, 2013, in the Oval Office of the White House. Standing, from left are, Rep. Terri Sewell, D-Ala., and Lisa McNair. Seated at right is Thelma "Maxine" Pippen McNair, the mother of Denise McNair. (AP Photo/Jacquelyn Martin)
President Barack Obama signs a bill designating the Congressional Gold Medal commemorating the lives of the four young girls killed in the 16th Street Baptist Church Bombing of 1963, Friday, May 24, 2013, in the Oval Office of the White House in Washington. Watching, from left are, Dr. Sharon Malone, wife of Attorney General Eric Holder; Attorney General Eric Holder and Rep. Terri Sewell, D-Ala. sponsor of the bill. (AP Photo/Jacquelyn Martin)
President Barack Obama speaks to the media in the Oval Office of the White House in Washington, Friday, May 24, 2013, before signing a bill designating the Congressional Gold Medal commemorating the lives of the four young girls killed in the 16th Street Baptist Church Bombing of 1963. From left are, Surgeon General Dr. Regina Benjamin; Birmingham Ala. Mayor William Bell; Dr. Sharon Malone, wife of Attorney General Eric Holder; Attorney General Eric Holder; Rep. Terri Sewell, D-Ala. sponsor of the bill; the president; Thelma "Maxine" Pippen McNair mother of Denise McNair; seated, Lisa McNair; Dianne Braddock sister of Carole Robertson, Rev. Arthur Price Jr., pastor of the Sixteenth Street Baptist Church, and former US Attorney Gordon Douglas Jones. (AP Photo/Jacquelyn Martin)
WASHINGTON (AP) ? President Barack Obama signed legislation Friday to award Congress' highest civilian honor to four girls killed in an Alabama church bombing during the civil rights movement. He called it a tragic loss that "helped to trigger triumph and a more just and equal and fair America."
The Congressional Gold Medal will go to Addie Mae Collins, Carole Robertson, Cynthia Wesley and Denise McNair.
Addie Mae, Carole and Cynthia, all 14, and Denise, 11, were killed when a bomb planted by white supremacists exploded at the 16th Street Baptist Church in Birmingham on Sept. 15, 1963. Twenty-two others were injured.
Denise's mother and sister, and Carole's sister were among those who stood around Obama's desk in the Oval Office as he signed the bill.
"For us to be able to be in this Oval Office with so many people who have worked hard to make this day possible, and understanding that that tragic loss, that heartbreak helped to trigger triumph and a more just and equal and fair America, that's an incredible thing for us to be able to participate in," he said.
September will mark the 50th anniversary of the bombing, which helped spur passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965.
Three Ku Klux Klan members were convicted of the bombing years after the attack. Two are dead and one is in prison.
While Congress widely embraced awarding the medal, the idea has divided the victims' relatives.
Some are supportive while others say they would prefer financial compensation and have little interest in the award.
Sisters of Denise and Carole sat in the House gallery during the debate and vote on the measure. Relatives of Addie Mae and Cynthia, also known as Cynthia Morris, have said they aren't interested in a medal. Addie Mae's sister lost an eye in the bombing.
Also present for the bill-signing was Attorney General Eric Holder and his wife, Sharon Malone. Her late sister, Vivian Malone Jones, was one of the first black students to enroll at the University of Alabama in 1963 in defiance of racial segregation.
Reps. Terri Sewell, a Democrat, and Spencer Bachus, a Republican, led the Alabama congressional delegation's efforts to honor the bombing victims. They represent adjoining Birmingham districts in Congress.
Past recipients of the Congressional Gold Medal include George Washington, Rosa Parks and Martin Luther King Jr., and his wife Coretta Scott King.
___
Associated Press writer Henry C. Jackson contributed to this report.
___
Follow Darlene Superville on Twitter: http://www.twitter.com/dsupervilleap
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The G-Spot Sports Show : Episode 4
Paul finished the 2011-2012 Fantasy Football season as the #1 Weekly Rankings & Projections winner of the 411Fantasy Expert Challenge. He also finished 2nd in the FantasyPros.com Expert Draft Accuracy Challenge in 2011. Top 10 Finisher in the FSWA Fantasy Football Draft Projections. Paul is also apart of baseballs elite as a member of Tout Wars. You can follow me on Twitter @PaulGreco
Friday, May 24, 2013
When oxygen is short, EGFR prevents maturation of cancer-fighting miRNAs
May 23, 2013 ? Even while being dragged to its destruction inside a cell, a cancer-promoting growth factor receptor fires away, sending signals that thwart the development of tumor-suppressing microRNAs (miRNAs) before it's dissolved, researchers reported in an early online publication at Nature.
Under conditions of oxygen starvation often encountered by tumors, the epidermal growth factor receptor (EGFR) gums up the cell's miRNA-processing machinery, an international team led by scientists at The University of Texas MD Anderson Cancer Center discovered.
"So when hypoxia stresses a cell, signaling by EGFR prevents immature miRNAs from growing up to fight cancer," said senior author Mien-Chie Hung, Ph.D., professor and chair of MD Anderson's Department of Molecular and Cellular Oncology and holder of the Ruth Legett Jones Distinguished Chair.
The group's findings point to a potential new prognostic marker for breast cancer, Hung noted, but also provide the first evidence of a growth factor signaling pathway regulating miRNA maturation.
"Inside of a cell, you have signal induction, in this case through EGFR, and you also have a protein complex that processes precursors into mature miRNA to perform a function. They didn't appear to talk to each other, it's as if one speaks English and the other Chinese," Hung said. "This is the first paper to show how they communicate."
The scientists established the relationship in cell line experiments, confirmed it in a mouse model and human breast cancer samples, then found that it reduced breast cancer patient survival in a review of 125 cases.
A new cancer-promoting role identified for EGFR
EGFR penetrates the cell membrane to receive signals from growth factors outside of the cell. After a growth factor binds to it, EGFR conveys the signal into the cell by attaching phosphate groups to other proteins, often acting as a molecular "on switch."
In many cancers, EGFR is overexpressed or dysfunctional, constantly sending signals to cells to divide. Hung and colleagues found that EGFR also fuels cancer progression by stifling tumor-suppressing miRNAs.
As a tumor grows, large portions of its interior can become starved for oxygen (hypoxia) for lack of adequate blood vessels. This stress suffocates many tumor cells, but the few that endure become highly malignant, resist treatment and are most likely to spread, Hung said.
Anti-angiogenesis drugs designed to kill tumors by blocking their ability to spin webs of supportive blood vessels often succeed at first, Hung said, but then fail against the more malignant cells that survive hypoxia.
When hypoxia hits, EGFR gets active and gets eaten
Low-oxygen conditions cause EGFR overexpression. EGFR also is pulled into the cell interior, captured in cavities called vesicles and eventually fed into lysosomes, a membrane-enclosed organelle loaded with enzymes to dissolve proteins.
It was known that EGFR continues to signal even while caught in the vesicles, which actually prolongs its activation. Hung and colleagues found that EGFR signals to a key protein in miRNA processing called argonaute 2, or AGO2.
AGO2 connects with two other proteins called Dicer and TRBP to form a complex that processes microRNA precursors into mature miRNAs, which regulate gene expression after messenger RNA has been expressed but before it's translated into a protein.
Oncoprotein-regulating miRNAs don't grow up
The scientists found that EGFR attaches phosphate groups to AGO2, which in turn weakens AGO2's ability to connect with Dicer to produce mature microRNAs. EGFR's effect is stronger during oxygen starvation than under normal conditions.
The team identified a number of specific miRNAs affected by EGFR, most of which have been reported to have tumor suppressor characteristics. The miRNAs regulated by phosphorylated AGO2, including miR-31, miR-192 and miR-193a-5p, also shared a long-loop structure in their precursors that miRNAs unaffected by AGO2 phosphorylation lack.
Hypoxic environments around tumors promote metastasis by helping cells evade programmed cell death. Hung and colleagues showed that EGFR-mediated AGO2 phosphorylation blocks cell death and enhances invasiveness under hypoxia.
Experiments in a mouse model of breast cancer confirmed that expression of EGFR and the presence of phosphorylated AGO2 increase during tumor progression under oxygen-starved conditions.
EGFR-AGO2 connection found in human breast tumors; reduces survival
The hypoxia-EGFR-AGO2 connection was strong in tumor samples from 128 breast cancer patients, but it was low or absent in normal breast tissue. In 125 breast cancer cases analyzed by the team, half of 62 patients with high levels of phosphorylated AGO2 survived to 48 months and beyond. Median survival had not been reached for the 63 patients in the low-level group, but 78 percent had survived to 48 months.
"One can imagine other receptors for platelet-derived growth factor and insulin-like growth factor also regulating miRNAs, perhaps by regulating Dicer or TBRP," Hung said. "This is a turning-point paper; it will induce lots of new questions for scientists to pursue."
Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/7P9oWD-qVgs/130523162256.htm
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David Land looks at how Gestamp Tallent Automotive is tackling its ...
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WWE's 5 hottest summer blockbusters
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