Cardiac surgeons install tiny temporary pump inside heart

Monday 19 August 2013

Islamabad, Aug 13 (Newswire): Cardiologists weave an eight gram pump through an artery in the groin into the left ventricle, where it pumps up to five liters of blood per minute.

This temporary device assists the heart as it recovers after surgery, prompting faster recovery.

Not only do patients need rest after heart surgery, so do their hearts! Next, a new device that helps weak hearts heal.

J.J. McCarthy is happy to be moved into his new home, but not long ago, breathing problems would have made even unpacking a box difficult. "I started having some shortness of breath and I went in to get it check out," he told Ivanhoe.

McCarthy learned he had a heart problem and needed bypass surgery, but a delicate heart can take a beating during surgery. "We repair a heart in surgery," Bartley Griffith, M.D., a heart surgeon at the University of Maryland Medical Center in Baltimore, told Ivanhoe. "It's a little bit like we create a bruise and the bruise has to heal in the heart."

Now, to help hearts heal after surgery, cardiac surgeons temporarily implant a new device that helps the heart pump blood, giving it a short-term rest. "It basically can perform the function of two-thirds of the heart, and so we let the heart kind of just hang out and repair itself," Dr. Griffith explains.

The tiny pump fits inside a catheter that is inserted through an artery in the groin leading to the heart. The device then helps pump blood in the left ventricle -- the heart's main pumping chamber. It's designed to support the heart for a week or less after surgery, allowing the heart to recover faster. "I think we can pull more patients through open heart surgery than we ever could before, because we have a powerful tool to assist the heart healing," Dr. Griffith says.

McCarthy needed the pump for just two days after surgery. His heart healed quickly and he was back on his feet. "I think it really shortened my recovery time a lot," McCarthy says. "I was able to get up and around a lot faster."

The heart pump device can pump up to five liters of blood per minute -- about three-quarters of a normal heart's output of seven liters per minute. After the device has done its job, it's removed from the patient.

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Darwin had it right all along

Islamabad, Aug 13 (Newswire): More than 150 years ago, Darwin proposed the theory of universal common ancestry (UCA), linking all forms of life by a shared genetic heritage from single-celled microorganisms to humans.

Until now, the theory that makes ladybugs, oak trees, champagne yeast and humans distant relatives has remained beyond the scope of a formal test. Now, a Brandeis biochemist reports in Nature the results of the first large scale, quantitative test of the famous theory that underpins modern evolutionary biology.

The results of the study confirm that Darwin had it right all along. In his 1859 book, On the Origin of Species, the British naturalist proposed that, "all the organic beings which have ever lived on this earth have descended from some one primordial form."

Over the last century and a half, qualitative evidence for this theory has steadily grown, in the numerous, surprising transitional forms found in the fossil record, for example, and in the identification of sweeping fundamental biological similarities at the molecular level.

Still, rumblings among some evolutionary biologists have recently emerged questioning whether the evolutionary relationships among living organisms are best described by a single "family tree" or rather by multiple, interconnected trees -- a "web of life."

Recent molecular evidence indicates that primordial life may have undergone rampant horizontal gene transfer, which occurs frequently today when single-celled organisms swap genes using mechanisms other than usual organismal reproduction. In that case, some scientists argue, early evolutionary relationships were web-like, making it possible that life sprang up independently from many ancestors.

According to biochemist Douglas Theobald, it doesn't really matter. "Let's say life originated independently multiple times, which UCA allows is possible," said Theobald. "If so, the theory holds that a bottleneck occurred in evolution, with descendants of only one of the independent origins surviving until the present. Alternatively, separate populations could have merged, by exchanging enough genes over time to become a single species that eventually was ancestral to us all. Either way, all of life would still be genetically related."

Harnessing powerful computational tools and applying Bayesian statistics, Theobald found that the evidence overwhelmingly supports UCA, regardless of horizontal gene transfer or multiple origins of life. Theobald said UCA is millions of times more probable than any theory of multiple independent ancestries.

"There have been major advances in biology over the last decade, with our ability to test Darwin's theory in a way never before possible," said Theobald. "The number of genetic sequences of individual organisms doubles every three years, and our computational power is much stronger now than it was even a few years ago."

While other scientists have previously examined common ancestry more narrowly, for example, among only vertebrates, Theobald is the first to formally test Darwin's theory across all three domains of life. The three domains include diverse life forms such as the Eukarya (organisms, including humans, yeast, and plants, whose cells have a DNA-containing nucleus) as well as Bacteria and Archaea (two distinct groups of unicellular microorganisms whose DNA floats around in the cell instead of in a nucleus).

Theobald studied a set of 23 universally conserved, essential proteins found in all known organisms. He chose to study four representative organisms from each of the three domains of life. For example, he researched the genetic links found among these proteins in archaeal microorganisms that produce marsh gas and methane in cows and the human gut; in fruit flies, humans, round worms, and baker's yeast; and in bacteria like E. coli and the pathogen that causes tuberculosis.

Theobald's study rests on several simple assumptions about how the diversity of modern proteins arose. First, he assumed that genetic copies of a protein can be multiplied during reproduction, such as when one parent gives a copy of one of their genes to several of their children. Second, he assumed that a process of replication and mutation over the eons may modify these proteins from their ancestral versions. These two factors, then, should have created the differences in the modern versions of these proteins we see throughout life today. Lastly, he assumed that genetic changes in one species don't affect mutations in another species -- for example, genetic mutations in kangaroos don't affect those in humans.

What Theobald did not assume, however, was how far back these processes go in linking organisms genealogically. It is clear, say, that these processes are able to link the shared proteins found in all humans to each other genetically. But do the processes in these assumptions link humans to other animals? Do these processes link animals to other eukaryotes? Do these processes link eukaryotes to the other domains of life, bacteria and archaea? The answer to each of these questions turns out to be a resounding yes.

Just what did this universal common ancestor look like and where did it live? Theobald's study doesn't answer this question. Nevertheless, he speculated, "to us, it would most likely look like some sort of froth, perhaps living at the edge of the ocean, or deep in the ocean on a geothermal vent. At the molecular level, I'm sure it would have looked as complex and beautiful as modern life."

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Faster salmonella detection now possible with new technique

Islamabad, Aug 13 (Newswire): Using technology available through a local company, an Iowa State University researcher is working on a faster method to detect and genetically identify salmonella from contaminated foods.

Byron Brehm-Stecher, an assistant professor of food science and human nutrition, wants to replace the current system of salmonella detection with a new approach that can provide DNA sequencing-like results in hours rather than days.

Brehm-Stecher's collaborator, Advanced Analytical Technologies, Inc., from Ames, is providing advanced biomedical instruments and reagents for the research.

The recent results of the research, funded by the Grow Iowa Values Fund, will be presented at the August meeting of the International Association for Food Protection in Anaheim, Calif.

Currently, definitive genetic identification of food-borne pathogens is done using traditional DNA sequencing methods first developed in the 1980s.

"If you want (DNA) sequence information now, you first need to run a polymerase chain reaction (PCR) on total DNA extracted from a sample of contaminated food," said Brehm-Stecher. "This amplifies DNA from the pathogen you're looking for and will let you know if salmonella is present or not.

"However, further details about the pathogen are lacking, like what strain is present. To dig deeper, you need to run a cycle sequencing reaction -- similar to a long PCR reaction -- and send the output from this to a DNA sequencing core facility. Results are available about two days later," said Brehm-Stecher.

"This is not fast enough to keep up with the pace of today's food production and distribution networks. We are able to get foods from the farm to the table -- really any table around the globe -- in a remarkably short period of time," he added.

Faster detection of specific strains can mean recognizing an outbreak sooner and stopping tainted food from being delivered and consumed. The new method might be helpful for investigative agencies, Brehm-Stecher said.

"Especially for the type of investigation where things are still in motion. The food has been shipped and you may not know where it is. It may be in a truck, on a shelf or in some consumer's pantry, so time really is of the essence," he said.

"Next-generation sequencing tools are available, but these are still too complex and expensive for routine use in the food industry," Brehm-Stecher explained. "New approaches that are able to bridge the gap between the limitations of traditional PCR and next-generation sequencing could enhance food safety efforts by providing both rapid presence/absence testing and detailed genetic characterization of isolates."

You don't have to go further than the local newspaper to see the depth of the problem. Recent national outbreaks of salmonella in foods include peanut butter (2007 and 2009), alfalfa sprouts (2009), black pepper and hydrolyzed vegetable protein (HVP) (2010). Adding to the problem is the fact that peanut butter, black pepper and HVP are all base ingredients used in many other food products. Salmonella in these ingredients has led to thousands of product recalls, hundreds of illnesses and several deaths, Brehm-Stecher said.

The method being developed at Iowa State University starts with a rapid PCR reaction that amplifies a salmonella-specific gene, generating millions of fluorescently labeled copies of this DNA in about 20 minutes.

Next, instead of cycle sequencing, the PCR product is purified for five minutes, SNAP71 (a reagent developed by Advanced Analytical) is added, and the DNA is heated for 10 minutes at 100ºC.

This reaction chemically cuts the labeled salmonella DNA at all adenine and guanine sites (A's and G's) in the DNA chain.

The result is a complex soup of fluorescently labeled DNA fragments of all sizes. These fragments are then separated in a high-voltage electric field by sieving them through a polymer matrix (a gel) contained in glass capillaries that are 50 microns -- not much thicker than a human hair. This process separates the DNA fragments according to their size, from smallest to largest, and each piece is detected as it passes in front of an intense light source. For a PCR product that's 300 bases long, this separation and detection process takes approximately 90 minutes.

Because the SNAP71 reagent cleaves the salmonella DNA only at adenine and guanine, and not at thymine and cytosine sites (T's and C's), the method is not a direct replacement for DNA sequencing. Instead, the process rapidly generates a reproducible pattern of DNA fragments, Brehm-Stecher said.

Salmonella strains having slightly different DNA sequences within a given gene will yield different patterns of fragments, allowing discrimination of different strains of salmonella.

From "food to finish," the whole process can be accomplished in about two and a half hours.

"We're very excited about this approach and about the rapid progress we've made since the project began," said Brehm-Stecher. "The funding for this project has enabled us to work very closely with Advanced Analytical and accelerate application of their instruments to solving important food safety problems."

The team at Iowa State University includes post doctoral researcher Hyun Jung Kim and master's student Brittany Porter. The group is also working with Cleveland Clinic in Ohio.

The ultimate goal of the project is faster detection and characterization of human pathogens from "farm to fork to physician."

Advanced Analytical's instruments are based on technology originally developed at Iowa State University in the lab of Ed Yeung, the Robert Allen Wright Professor and Distinguished Professor in Liberal Arts and Sciences and professor at the U.S. Department of Energy's Ames Lab.

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