Neuronal Circuits Able To Rewire On The Fly To Sharpen Senses

Source:

http://www.sciencedaily.com/releases/2007/12/071216155630.htm

ScienceDaily (Dec. 22, 2007) — Researchers from the Center for the Neural Basis of Cognition (CNBC), a joint project of Carnegie Mellon University and the University of Pittsburgh, have for the first time described a mechanism called "dynamic connectivity," in which neuronal circuits are rewired "on the fly" allowing stimuli to be more keenly sensed.

This new, biologically inspired algorithm for analyzing the brain at work allows scientists to explain why when we notice a scent, the brain can quickly sort through input and determine exactly what that smell is.
"If you think of the brain like a computer, then the connections between neurons are like the software that the brain is running. Our work shows that this biological software is changed rapidly as a function of the kind of input that the system receives," said Nathan Urban, associate professor of biological sciences at Carnegie Mellon.
When a stimulus such as an odor is encountered, many neurons start to fire. When many neurons fire at the same time, the signals can be difficult for the brain to interpret. During lateral inhibition, the stimulated neurons send "cease-fire" messages to the neighboring neurons, reducing the noise and making it easier to precisely identify a stimulus. This process also facilitates accurate recognition of stimuli in many sensory areas of the brain.
In this project, Urban and colleagues specifically examine the process of lateral inhibition in an area of the brain called the olfactory bulb, which is responsible for processing scents. Until now, scientists thought that the connections made by the neurons in the olfactory bulb were dictated by anatomy and could only change slowly.
However, in this current study, Urban and colleagues found that the connections are, in fact, not set but rather able to change dynamically in response to specific patterns of stimuli. In their experiments, they found that when excitatory neurons in the olfactory bulb fire in a correlated fashion, this determines how they are functionally connected.
The researchers showed that dynamic connectivity allows lateral inhibition to be enhanced when a large number of neurons initially respond to a stimulus, filtering out noise from other neurons. By filtering out the noise, the stimulus can be more clearly recognized and separated from other similar stimuli.
"This mechanism helps to explain why you can walk into a room and recognize a smell that seems to be floral. As you continue to smell the odor, you begin to recognize that the scent is indeed flowers and even more specifically is the scent of roses," Urban said. "By understanding how the brain does this, we can then apply this mechanism to other problems faced by the brain."
Researchers converted this mechanism into an algorithm and used computer modeling to further show that dynamic connectivity makes it easier to identify and discriminate between stimuli by enhancing the contrast, or sharpness, of the stimuli, independent of the spatial patterns of the active neurons. This algorithm allows researchers to show the applicability of the mechanism in other areas of the brain where similar inhibitory connections are widespread. For example, the researchers applied the algorithm to a blurry picture and the picture appeared refined and in sharper contrast (see image).
The process is described in a paper in the January 2008 issue of Nature Neuroscience, and available online at http://dx.doi.org/10.1038/nn2030.
Coauthors of the study include Armen Arevian, a graduate student in the Center for Neuroscience at the University of Pittsburgh, and Vikrant Kapoor, a biological sciences graduate student at Carnegie Mellon. The study was funded through grants from the National Institute on Deafness and Other Communication Disorders, and the National Science Foundation.
Adapted from materials provided by Carnegie Mellon University.

Fausto Intilla

www.oloscience.com

New Gene Therapy Heals Growth Deficiency Disorder In Live Animal

Source:

http://www.sciencedaily.com/releases/2007/12/071218192020.htm

ScienceDaily (Dec. 20, 2007) — A team of Vanderbilt researchers have demonstrated for the first time that a new type of gene therapy, called RNA interference, can heal a genetic disorder in a live animal.

The study shows that RNA interference can "rescue" a strain of mouse that has been genetically engineered to express a defective human hormone that interferes with normal growth. When the gene that produces the defective human growth hormone is inserted into the mouse's genome, it also stunts the mouse's growth. But when a small snippet of RNA that interferes with the hormone's production is also added, the mouse is restored to normal.
"It has been very satisfying to figure out the underlying cause of this genetic disorder and then identify a way to prevent it," says John Phillips, the David T. Karzon Professor of Pediatrics at the Vanderbilt University Medical Center, who has been studying human growth deficiency disorders since 1978. He collaborated on the research with graduate students Nikki Shariat and Robin Ryther, who are directed by Professor of Biological Sciences James G. Patton.
Growth hormone deficiency has been estimated to occur in between one in 4,000 to 10,000 children. It has a number of different causes, but one that is genetically inherited is called Isolated Growth Hormone Deficiency type II, and this is the subject of the study.
Children with IGHD-II appear fairly normal at birth but do not gain weight or grow as fast as they should, and their bones do not mature properly. The current treatment consists of daily injections of growth hormone for years until the patients reach their adult height. Not only is this treatment extremely expensive, it also fails to correct the underlying source of the problem: deterioration and death of cells in the pituitary gland that produce growth hormone. As a result, this single hormone deficiency can develop into multi-hormonal deficiency over time.
IGHD-II is what geneticists call a dominant negative disorder. It is caused by a defective form of human growth hormone that not only can't stimulate growth itself but also blocks the action of normal growth hormone. "It acts like Aesop's dog in the manger ... which has no use for the hay but keeps the cows from eating," says Phillips. Some other common dominant negative diseases include forms of colon cancer, deafness, muscular dystrophy, brittle bone disease, kidney disease and retinitis pigmentosa.
The blueprint for a protein like growth hormone is genetically encoded in a series of special segments called exons. The instructions in the exons are first copied onto a length of special RNA, called messenger-RNA. The messenger-RNA is moved to a structure in the cell called a ribosome, which links amino acids together in the order specified by the RNA sequence to create the protein.
Normal growth hormone is produced by a series of five exons. The defective hormone is the result of a splicing error: It is made by combining the segments coded by the first two exons and the last two exons, mistakenly skipping the third exon.
"A normal person has a very small amount of this defective hormone -- about 1 percent -- but people in families with IGHD-II produce 10 to 20 to 50 percent. And the more they make the slower they grow," says Patton.
In 2003, co-author Iain Robinson at the National Institute for Medical Research in London created a transgenic mouse with the human growth hormone gene that duplicated growth hormone deficiency. Although the altered mice still contained the mouse growth hormone genes, he found that high levels of the defective human growth hormone not only stunted their growth but actually killed the cells in the pituitary that produce growth hormone.
"This came as a real surprise: We never thought that a splicing error would lead to cell death," says Patton.
Meanwhile, progress in RNA interference research gave Patton and Phillips an idea for a way to correct this disorder.
In the last 15 years, scientists have realized that short pieces of double-stranded RNA, called silencing-RNA, use a pathway that is normally used by cells to regulate genes. This has created an opportunity for developing highly targeted therapies for a number of genetic diseases including macular degeneration in the eye and to block viruses such as herpes and RSV respiratory viruses. "To the best of our knowledge, this is the first time it has been used to correct a dominant negative disorder in a living animal," says Patton.
The researchers realized that the messenger-RNA that produced the defective hormone had a unique signature created by skipping the third exon. This allowed the Patton lab to create a specific silencing-RNA, designed to bind uniquely with the defective messenger-RNA.
"You might call this the 'if you don't like the message, kill the messenger' approach," Phillips quips.
Having created the special silencing-RNA, the next problem was how to deliver it to the pituitary gland which, in the case of the mouse, is the size of a grain of uncooked rice and is located at the base of the brain. As a proof of concept, the researchers decided to create a second strain of mouse which carried the special silencing-RNA and mate them with the growth deficiency strain. Their offspring should have both the genetic defect that produces the defective growth hormone and the silencing-RNA that should inhibit its production, allowing the mouse growth hormone to act.
The experiment was successful. The offspring grew normally and showed no defects in their pituitaries.
Now the researchers are investigating ways to deliver their silencing-RNA to the pituitary gland that would be suitable for treating humans. The cells that produce growth hormone have special receptors that signal the cells to release their stocks of growth hormone. If they can figure out a way to attach the silencing-RNAs to a compound that binds to this receptor, they should be able to deliver them to the cells where they can interfere with the activity of the defective growth hormone.
This research was published online Nov. 15 by the journal Endocrinology.
Adapted from materials provided by Vanderbilt University.

Fausto Intilla

www.oloscience.com

Engineering Blood Vessels That Could Be Used In Human Body

Source:

http://www.sciencedaily.com/releases/2007/12/071217155248.htm

ScienceDaily (Dec. 19, 2007) — MIT scientists have found a way to induce cells to form parallel tube-like structures that could one day serve as tiny engineered blood vessels.

The researchers found that they can control the cells' development by growing them on a surface with nano-scale patterning.
Engineered blood vessels could one day be transplanted into tissues such as the kidneys, liver, heart or any other organs that require large amounts of vascular tissue, which moves nutrients, gases and waste to and from cells.
"We are very excited about this work," said Robert Langer, MIT Institute Professor and an author of the paper. "It provides a new way to create nano-based systems with what we hope will provide a novel way to someday engineer tissues in the human body." A paper on the work was posted this month in an online issue of Advanced Materials.
The work focuses on vascular tissue, which includes capillaries, the tiniest blood vessels, and is an important part of the circulatory system. The team has created a surface that can serve as a template to grow capillary tubes aligned in a specific direction.
The researchers built their template using microfabrication machinery at Draper Laboratory in Cambridge. Normally such technology is used to build micro-scale devices, but the researchers adapted it to create nano-scale patterns on a silicone elastomer substrate. The surface is patterned with ridges and grooves that guide the cells' growth.
"The cells can sense (the patterns), and they end up elongated in the direction of those grooves," said Christopher Bettinger, MIT graduate student in materials science and engineering and lead author of the paper.
The cells, known as endothelial progenitor cells (EPCs), not only elongate in the direction of the grooves, but also align themselves along the grooves. That results in a multicellular structure with defined edges, also called a band structure.
Once the band structures form, the researchers apply a commonly used gel that induces cells to form three-dimensional tubes. Unlike cells grown on a flat surface, which form a network of capillary tubes extending in random directions, cells grown on the nano-patterned surface form capillaries aligned in the direction chosen by the researchers.
The researchers believe the technique works best with EPCs because they are relatively immature cells. Earlier attempts with other types of cells, including mature epithelial cells, did not produce band structures.
Growing tissue on a patterned surface allows researchers a much greater degree of control over the results than the classic tissue engineering technique of mixing cell types with different growth factors and hoping that a useful type of tissue is produced, said Bettinger.
"With this technique, we can take the guesswork out of it," he said.
The next step is to implant capillary tubes grown in the lab into tissues of living animals and try to integrate them into the tissues.
Other authors of the paper are Jeffrey Borenstein, director of the Biomedical Engineering Center at Draper Laboratory; Zhitong Zhang, an MIT senior in the Department of Chemical Engineering; and Sharon Gerecht of Johns Hopkins University.
The research was funded by the National Institutes of Health, Draper Laboratory and the Juvenile Diabetes Research Foundation.
Adapted from materials provided by Massachusetts Institute of Technology.

Fausto Intilla

www.oloscience.com

Sperm's Immune-protection Properties Could Provide Link To How Cancers Spread

Source:

http://www.sciencedaily.com/releases/2007/12/071213101352.htm

ScienceDaily (Dec. 19, 2007) — Sugar-based markers on human sperm cells which may prevent them from being attacked by the female immune system could provide a vital clue to how some cancers spread in the human body, according to new research.

The new research analysed these markers which are believed to tell the female immune system that the sperm are not dangerous pathogens, and therefore should not be attacked by the woman's white blood cells during the reproductive process. The study*, led by Imperial College London and the University of Missouri, suggests that these sugar markers, found on N-glycans which are part of human sperm glycoproteins, can be universally recognised by all human immune systems, regardless of the individual.
Professor Anne Dell from Imperial College London's Department of Life Sciences, one of the study's lead authors, said: "Normal human cells carry chemical markers made of proteins which tell the immune system not to attack them. In the case of organ transplants, for example, doctors try to match these markers in both the donor and the recipient to prevent rejection. However, in the case of sperm cells, their sugar-based markers are different: they are recognised by everyone's immune system, meaning that no immune response is triggered during reproduction between any two people."
This kind of marker is also found on some types of cancer cells, some bacterial cells, some parasitic worms and HIV infected white blood cells. The scientists believe that these markers allow such dangerous cells and pathogens to evade destruction by the human immune system, leading to serious -- sometimes fatal - illness.
Professor Dell explains that understanding how this basic biology works on sperm cells may lead to greater knowledge of how some serious diseases and infections manage to win the battle with the human immune system. She says:
"If aggressive cancers and pathogens are using the same system of universally-recognisable markers to trick the immune system into thinking they're harmless, we need to work out exactly how this interaction works. This is where we're planning to take this research next. Understanding how these markers work at a basic biological and chemical level could lead to new ways to treat or prevent cancers and other diseases in the future."
*The study, 'Expression of Bisecting Type and Lewisx/Lewisy Terminated N-Glycans on Human Sperm', was published on 14 December 2007 in the Journal of Biological Chemistry.
Adapted from materials provided by Imperial College London.

Fausto Intilla

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New Hope For Sleep Disorders: Genetic Switch For Circadian Rhythms Discovered

Source:

http://www.sciencedaily.com/releases/2007/12/071212201458.htm

ScienceDaily (Dec. 18, 2007) — University of California, Irvine researchers have identified the chemical switch that triggers the genetic mechanism regulating our internal body clock.

The finding, which uncovers the most specific information about the body's circadian rhythms to date, identifies a precise target for new pharmaceuticals that can treat sleep disorders and a host of related ailments.
Paolo Sassone-Corsi, Distinguished Professor and Chair of Pharmacology, found that a single amino acid activates the genes that regulate circadian rhythms. Amino acids are the building blocks of proteins, and Sassone-Corsi was surprised to find that only a single amino acid activates the body-clock mechanism because of the complex genes involved.
"Because the triggering action is so specific, it appears to be a perfect target for compounds that could regulate this activity," Sassone-Corsi said. "It is always amazing to see how molecular control is so precise in biology."
Circadian rhythms are the body's intrinsic time-tracking system, which anticipates environmental changes and adapts to the appropriate time of day. They regulate a host of body functions, from sleep patterns and hormonal control to metabolism and behavior. About 10 percent to 15 percent of all human genes are regulated by circadian rhythms. Disruption of these rhythms can profoundly influence human health and has been linked to insomnia, depression, heart disease, cancer and neurodegenerative disorders.
The gene CLOCK and its partner BMAL1 trigger circadian rhythms. Sassone-Corsi and his research team discovered last year that CLOCK functions as an enzyme that modifies chromatin, the protein architecture of a cell's DNA.
In this current study, the Sassone-Corsi team learned that a single amino acid in the BMAL1 protein undergoes a modification that triggers the genetic chain of events involved with circadian rhythms.
Sassone-Corsi notes that if this amino-acid modification is impaired in any way, the switching mechanism can be thrown off, which can be the genetic underpinning of circadian-rhythm-related ailments. Currently, Sassone-Corsi is testing antibodies that can target this BMAL1 amino-acid activity.
The study appears in the Dec. 13 issue of Nature.
Jun Hirayama, Saurabh Sahar, Benedetto Grimaldi and Yasukazu Nakahata of UC Irvine, and Teruya Tamaru and Ken Takamatsu of Toho University in Tokyo participated in the study, which received support from the Cancer Research Coordinating Committee of the University of California and the National Institutes of Health.
Adapted from materials provided by University of California - Irvine.

Fausto Intilla

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Laser Beam 'Fire Hose' Used To Sort Cells; Could Enable New Kinds Of Biological Research

Source:

http://www.sciencedaily.com/releases/2007/12/071210163008.htm

ScienceDaily (Dec. 17, 2007) — Separating particular kinds of cells from a sample could become faster, cheaper and easier thanks to a new system developed by MIT researchers that involves pushing up the cells with a laser beam "fire hose."

The system, which can sort up to 10,000 cells on a conventional glass microscope slide, could enable a variety of biological research projects that might not have been feasible before, its inventors say. It could also find applications in clinical testing and diagnosis, genetic screening and cloning research, all of which require the selection of cells with particular characteristics for further testing.
Joel Voldman, an associate professor in MIT's Department of Electrical Engineering and Computer Science, and Joseph Kovac, a graduate student in the department, developed the new system, which is featured as the cover story in the Dec. 15 issue of the journal Analytical Chemistry.
Present methods allow cells to be sorted based on whether or not they emit fluorescent light when mixed with a marker that responds to a particular protein or other compound. The new system allows more precise sorting, separating out cells based not just on the overall average fluorescent response of the whole cell but on responses that occur in specific parts of the cell, such as the nucleus. The system can also pick up responses that vary in how fast they begin or how long they last.
"We've been interested in looking at things inside the cell that either change over time, or are in specific places," Voldman said. Separating out cells with such characteristics "can't be done with traditional cell sorting."
For example, if cells differ in how quickly they respond to a particular compound used in the fluorescent labeling, the new system would make it possible to "select out the ones that are faster or slower, and see what's different," said Voldman, who also has appointments in MIT's Research Laboratory of Electronics and the Microsystems Technology Laboratories.
"It seems like that should be easy, but it isn't," he said. There are other ways of accomplishing the same kind of cell separation, but they require complex and expensive equipment, or are limited in the number of cells they can process.
The new system uses a simple transparent silicone layer bonded to a conventional glass microscope slide. Fabricated in the layer are a series of tiny cavities, or traps, in which cells settle out after being added to the slide in a solution. Up to 10,000 cells could be sorted on a single slide.
Looking through the microscope, either a technician or a computerized system can check each cell to determine whether it has fluorescence in the right area or at the right time to meet the selection criteria. If so, its position is noted by the computer. At the end of the selection process, all of the cells whose positions were recorded are then levitated out of their traps using the pressure of a beam of targeted light from a low-cost laser. A flowing fluid then sweeps the selected cells off to a separate reservoir.
The laser levitation of the cells acts like "a fire hose pushing up a beach ball," Voldman said. But the laser method is gentle enough that the living cells remain viable after the process is complete, allowing further biological testing.
Voldman and Kovac are continuing to refine the system, working on making it easier to use and on improving its ability to keep samples sterile. Voldman said that unlike expensive separation techniques such as optical tweezers, the new system could cost only a few thousand dollars. As a result, it could be employed in a variety of biological research laboratories or clinical settings, not just in big, centralized testing facilities.
The research was funded by the National Institutes of Health and the Singapore-MIT Alliance; Kovac is supported by an ASEE National Defense Science and Engineering Graduate Fellowship.
Adapted from materials provided by Massachusetts Institute of Technology.

Fausto Intilla

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Losses Of Long-established Genes Contribute To Human Evolution

Source:

http://www.sciencedaily.com/releases/2007/12/071214094129.htm

ScienceDaily (Dec. 15, 2007) — While it is well understood that the evolution of new genes leads to adaptations that help species survive, gene loss may also afford a selective advantage. A group of scientists at the University of California, Santa Cruz led by biomolecular engineering professor David Haussler has investigated this less-studied idea, carrying out the first systematic computational analysis to identify long-established genes that have been lost across millions of years of evolution leading to the human species.

Haussler and five others in his group--postdoc Jingchun Zhu, graduate students Zack Sanborn and Craig Lowe, technical projects manager Mark Diekhans, and evolutionary biologist Tom Pringle--are co-authors on the paper*.
"The idea that gene losses might contribute to adaptation has been kicked around, but not well studied," said Zhu, who is first author of the paper. "We found three examples in the literature, and all of them could have medical implications."
To find gene losses, Zhu employed a software program called TransMap that Diekhans had developed. The program compared the mouse and human genomes, searching for genes having changes significant enough to render them nonfunctional somewhere during the 75 million years since the divergence of the mouse and the human.
"This is the first study designed to search the entire genome for recent loss of genes that do not have any near-duplicate copies elsewhere in the genome," said Haussler. "These are likely to be the more important gene losses."
Genes can be lost in many ways. This study focused on losses caused by mutations that disrupt the open reading frame (ORF-disrupting mutations). These are either point mutations, where events such as the insertion or substitution of a DNA base alter the instructions delivered by the DNA, or changes that occur when a large portion of a gene is deleted altogether or moves to a new place on the genome.
"We used the dog genome as an out-group to filter out false positives," Sanborn explained, because the dog diverged from our ancient common ancestor earlier than the mouse. "If a gene is still living in both dog and mouse but not in human, it was probably living in the common ancestor and then lost in the human lineage."
Using this process, they identified 26 losses of long-established genes, including 16 that were not previously known.
The gene loss candidates found in this study do not represent a complete list of gene losses of long-established genes in the human lineage, because the analysis was designed to produce more false negatives than false positives.
Next they compared the identified genes in the complete genomes of the human, chimpanzee, rhesus monkey, mouse, rat, dog, and opossum to estimate the amount of time the gene was functional before it was lost. This refined the timing of the gene loss and also served as a benchmark for whether the gene in question was long-established, and therefore probably functional, or merely a loss of a redundant gene copy. Through this process, they found 6 genes that were lost only in the human.
One previously unknown loss, the gene for acyltransferase-3 (ACYL3), particularly caught their attention. "This is an ancient protein that exists throughout the whole tree of life," said Zhu. Multiple copies of the ACYL3 gene are encoded in the fly and worm genomes. "In the mammalian clade there is only one copy left, and somewhere along primate evolution, that copy was lost."
"In our analysis, we found that this gene contains a nonsense mutation in human and chimp, and it appears to still look functional in rhesus," said Sanborn. Further, they found that the mutation is not present in the orangutan, so the gene is probably still functional in that species.
"On the evolutionary tree leading to human, on the branch between chimp and orangutan sits gorilla," explained Sanborn. Knowing if the gene was still active in gorilla would narrow down the timing of the loss.
Sanborn took to the wet laboratory to sequence the corresponding region in a DNA sample from a gorilla. The gorilla DNA sequence showed the gene intact, without the mutation, so the loss likely occurred between the speciation of gorilla and chimpanzee.
"Acyltransferase-3 was not the only lost gene that doesn't have any close functional homologues in the human genome. A highlight of our research was that we were able to find a list of these 'orphan losses,'" said Zhu. "Some of them have been functional for more than 300 million years, and they were the last copies left in the human genome." While the copies of these genes remaining in the human genome appear to be nonfunctional, functional copies of all of them exist in the mouse genome.
"These orphan genes may be interesting candidates for experimental biologists to explore," said Zhu. "It would be interesting to find out what was the biological effect of these losses. Once their function is well characterized in species that still have active copies, we could maybe speculate about their effects on human evolution."
*Their findings appear in the December 14 issue of PLoS Computational Biology.
This research was funded by the National Human Genome Research Institute, the National Institutes of Health, the National Cancer Institute, and the Howard Hughes Medical Institute.
Adapted from materials provided by University of California - Santa Cruz.

Fausto Intilla

www.oloscience.com

Scientists Overcome Major Obstacles To Stem Cell Heart Repair

Source:

http://www.sciencedaily.com/releases/2007/12/071212201501.htm

ScienceDaily (Dec. 13, 2007) — Scientists at Imperial College London have overcome two significant obstacles on the road to harnessing stem cells to build patches for damaged hearts. Presenting the research at a UK Stem Cell Initiative conference December 13 in Coventry, research leader Professor Sian Harding has explained how her group have made significant progress in maturing beating heart cells (cardiomyocytes) derived from embryonic stem cells and in developing the physical scaffolding that would be needed to hold the patch in place in the heart in any future clinical application.

From the outset the Imperial College researchers have been aiming to solve two problems in the development of a stem cell heart patch. The first is undesirable side effects, such as arrhythmia, that can result from immature and undeveloped cardiomyocytes being introduced to the heart. The second is the need for a scaffold that is biocompatible with the heart and able to hold the new cardiomyocytes in place while they integrate into the existing heart tissue. Matching the material to human heart muscle is also hoped to prevent deterioration of heart function before the cells take over.
The stem cell team, led by Dr Nadire Ali, co-investigator on the grant*, have managed to follow beating embryonic stem cell-derived cardiomyocytes for up to seven months in the laboratory and demonstrate that these cells do mature. In this period the cells have coordinated beating activity, and they adopt the mature controls found in the adult heart by approximately four months after their generation from embryonic stem cells. These developed cardiomyocytes will then be more compatible with adult heart and less likely to cause arrhythmias.
The team have also overcome hurdles in the development of a biocompatible scaffold. Working closely with a group of biomaterial engineers, led by Dr Aldo Boccaccini and Dr Qizhi Chen, co-investigators on the grant, in the Department of Materials, Imperial College London, they have developed a new biomaterial with high level of biocompatibility with human tissue, tailored elasticity and programmable degradation. The latter quality is important as any application in the heart needs to be able to hold cells in place long enough for them to integrate with the organ but then degrade safely away. The researchers have found that their material, which shares the elastic characteristics of heart tissue, can be programmed to degrade in anything from two weeks upwards depending on the temperatures used during synthesis.
Professor Harding said: "Although we are still some way from having a treatment in the clinic we have made excellent progress on solving some of the basic problems with stem cell heart therapies. The work we have done represents a step forward in both understanding how stem cell-derived developing heart cells can be matured in the laboratory and how materials could be synthesised to form a patch to deliver them to damaged areas of the heart.
"A significant amount of hard work and research remains to be done before we will see this being used in patients but the heart is an area where stem cell therapies offer promise. We know that the stem cell-derived cardiomyocytes will grow on these materials, and the next step is to see how the material and cell combination behave in the long term."
Professor Nigel Brown, BBSRC Director of Science and Technology, commented: "This research shows that although embryonic stem cell therapies are still some way away from the clinic, progress is being made on the basic biological developments. As with all new biomedical applications, an understanding of the underpinning fundamental science is essential to successfully moving forward."
*This research was funded by the Biotechnology and Biological Sciences Research Council.
Adapted from materials provided by Biotechnology and Biological Sciences Research Council.

Fausto Intilla

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Researchers Can Read Thoughts To Decipher What A Person Is Actually Seeing

Source:

http://www.sciencedaily.com/releases/2007/12/071206222634.htm

ScienceDaily (Dec. 11, 2007) — Following ground-breaking research showing that neurons in the human brain respond in an abstract manner to particular individuals or objects, University of Leicester researchers have now discovered that, from the firing of this type of neuron, they can tell what a person is actually seeing.

The original research by Dr R Quian Quiroga, of the University’s Department of Engineering, showed that one neuron fired to, for instance, Jennifer Aniston, another one to Halle Berry, another one to the Sydney Opera House, etc.
The responses were abstract. For example, the neuron firing to Halle Berry responded to several different pictures of her and even to the letters of her name, but not to other people or names.
This result, published in Nature in 2005 came from data from patients suffering from epilepsy. As candidates for epilepsy surgery, they are implanted with intracranial electrodes to determine as accurately as possible the area where the seizures originate. From that, clinicians can evaluate the potential outcome of curative surgery.
Dr Quian Quiroga’s latest research, which has appeared in the Journal of Neurophysiology, follows on from this.
Dr Quian Quiroga explained: “For example, if the 'Jennifer Aniston neuron' increases its firing then we can predict that the subject is seeing Jennifer Aniston. If the 'Halle Berry neuron' fires, then we can predict that the subject is seeing Halle Berry, and so on.
“To do this, we used and optimised a 'decoding algorithms', which is a mathematical method to infer the stimulus from the neuronal firing. We also needed to optimise our recording and data processing tools to record simultaneously from as many neurons as possible. Currently we are able to record simultaneously from up to 100 neurons in the human brain.
“In these experiments we presented a large database of pictures, and discovered that we can predict what picture the subject is seeing far above chance. So, in simple words, we can read the human thought from the neuronal activity.
“Once we reached this point, we then asked what are the most fundamental features of the neuronal firing that allowed us to make this predictions. This gave us the chance of studying basic principles of neural coding; i.e. how information is stored by neurons in the brain.
“For example, we found that there is a very limited time window in the neuronal firing that contains most of the information used for such predictions. Interestingly, neurons fired only 4 spikes in average during this time window. So, in another words, only 4 spikes of a few neurons are already telling us what the patient is seeing.”
Potential applications of this discovery include the development of Neural Prosthetic devices to be used by paralysed patients or amputees. A patient with a lesion in the spinal cord (as with the late Christopher Reeves), can still think about reaching a cup of tea with his arm, but this order is not transmitted to the muscles.
The idea of Neural Prostheses is to read these commands directly from the brain and transmit them to bionic devices such as a robotic arm that the patient could control directly from the brain.
Dr Quian Quiroga’s work showing that it is possible to read signals from the brain is a good step forward in this direction. But there are still clinical and ethical issues that have to be resolved before Neural Prosthetic devices can be applied in humans.
In particular, these would involve invasive surgery, which would have to be justified by a clear improvement for the patient before it could be undertaken.
Adapted from materials provided by University of Leicester.

Fausto Intilla

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'Oosight' Microscope Enables Embryonic Stem Cell Breakthrough

Source:

http://www.sciencedaily.com/releases/2007/11/071129183731.htm

ScienceDaily (Dec. 3, 2007) — A noninvasive, polarized light microscope invented at the Marine Biological Laboratory (MBL) played a crucial role in a recent breakthrough in embryonic stem-cell research aimed at developing medical therapies.

A team led by Shoukhrat Mitalipov, Ph.D., of Oregon Health & Science University reported the successful derivation of stem cells from cloned monkey embryos in the November 22 issue of Nature. While embryonic stem cells have been made from cloned embryos in a mouse, this is the first time they have been produced in a primate.
In humans, this method for deriving stem cells is a potential way to make "custom" tissues that are genetically identical to a patient, which would avoid rejection by the patient's immune system. Stem cells, in theory, can be induced to become any type of cell, tissue or organ. However, in recent years, some investigators had claimed it wouldn't be technically possible to make embryonic stem cells from monkeys or humans using this method (somatic cell nuclear transfer, or therapeutic cloning).
Mitalipov's stem-cell derivation succeeded, he says, largely due to the Oosight ™ microscope system developed by Cambridge Research & Instrumentation Inc. (CRi) of Woburn Mass., using technology invented at the MBL by senior scientist Rudolf Oldenbourg, Ph.D., and research associate Guang Mei, Ph.D. Former MBL research scientists David L. Keefe, M.D., and Lin Liu, Ph.D., both of whom teach in the MBL's Frontiers in Reproduction course, worked with Oldenbourg to adapt the technology for somatic cell nuclear transfer and embryology.
"The use of the Oosight was one of the major modifications we made in our present work," Mitalipov says.
The Oosight allowed Mitalipov's team to clearly see and remove the meiotic spindle from 304 female rhesus monkey eggs. This is the first step in therapeutic cloning, called enucleation. Next, they inserted the genetic material from the skin cells of an adult male rhesus monkey into the eggs and allowed them to grow to the blastocyst stage. From these cloned embryos, the researchers obtained two viable stem cell lines that are genetically identical to the adult male monkey.
"We are thrilled that the Oosight worked for enucleating monkey eggs," says Keefe. "We already had shown at the MBL, in 2000, that the technology developed by Dr. Oldenbourg facilitated noninvasive enucleation of mice eggs." At that time, Keefe operated a research lab at the MBL and directed the Division of Reproductive Medicine and Infertility at Women & Infants Hospital in Providence, R.I. Keefe is presently professor and chair of the Department of Obstetrics and Gynecology at the University of South Florida College of Medicine.
"Before, the problem was always that you could not see the spindle in the egg," Mitalipov says. "The only way to see it was to stain it with dyes. And that, we found, was very detrimental for egg quality." The Oosight uses liquid-crystal polarized light technology to image the spindle noninvasively, with high contrast and quality.
"You can actually look in the Oosight microscope and see the spindle with your eyes, not frozen as a computer screen image," says Mitalipov, which is critical for the next step: taking the spindle out of the egg. "You can't manipulate the egg while looking at a computer screen. You have to look at the egg. The Oosight, plus very skilled micromanipulations of the eggs, gave us a 100% success rate with enucleating."
The Oosight is based on technology that is the result of decades of MBL research pioneered by Distinguished Scientist Shinya Inoué. In the 1950s, Inoué was one of the first cytologists to make extensive use of the polarized light microscope to observe birefringent components of the cell, which led to his landmark discovery in 1951 of the meiotic spindle fibers in living cells. He later showed that dynamic disassembly of the spindle fibers can produce force that moves the chromosomes toward the poles of the cell during mitosis or meiosis.
In 1957, Inoué added a polarization rectifier to his custom-built microscope, which dramatically decreased distortion and improved the contrast of the image. Rudolf Oldenbourg further improved the polarizing microscope in the mid-1990s, adding liquid crystals with electro-optical controls and software. This version, called the LC-PolScope, allows one to simultaneously measure the birefringence in every resolved specimen point across the entire viewing field of the microscope; traditional models could only measure a single point of the specimen at a time. The LC-PolScope continues to be refined and expanded for live cell imaging at the MBL. Its technology is being adapted to different application areas by Cambridge Research & Instrumentation and is sold under trademarks such as Oosight and Abrio.
In the mid-1990s, David Keefe set up a lab at the MBL in order to collaborate with Oldenbourg and Inoué. Keefe was interested in finding out if the noninvasive LC-PolScope could be used in clinical settings to evaluate the quality of human eggs prior to in vitro fertilization procedures, and thus reduce the number of nonviable embryos created; and to improve the efficiency of therapeutic cloning in animals.
"When I was training as an ob-gyn at Yale in the mid 1980s, we were one of the first places to use ultrasound to assess the health of babies in utero," Keefe says. "As a student in the MBL Physiology Course, I learned of Drs. Inoué's and Oldenbourg's work, and realized we could use the polarizing microscope to assess health even earlier during development -- back to the beginning, at the egg stage -- without hurting the egg," Keefe says.
Using the LC-PolScope, Keefe, Oldenbourg and collaborators reported for the first time on layers of birefringence in the egg's zona pellucida in 1997. In 2000, Lin Liu, Keefe, Oldenbourg and collaborators reported that the polarized light microscope also helped enucleate mouse eggs, the critical step during somatic cell nuclear transfer, and proposed that this approach would improve the efficiency and safety of therapeutic cloning (Nature Biotech. 18: 223-225).
The LC-PolScope was commercialized first as the SpindleView in 1999, later as the Oosight in 2005, with improvements for fast viewing contributed by Michael Shribak, Ph.D., associate research scientist at the MBL. The Oosight has the same optical components and the algorithms as the LC-PolScope, but it is simplified for routine operation. While polarized light microscopy is now used throughout the world in infertility clinics, and was proposed as an aid to cloning research, its actual application to cloning research was not appreciated until the recent Nature paper by Mitalipov et al.
"In spirit and in application, the Oosight really expands on what Shinya Inoué started in the 1950s," says Oldenbourg. "And it was David Keefe's vision that the LC-PolScope could be used for in vitro fertilization or for enucleation, since it can be used to visualize the spindle without staining it with dyes."
"It's very significant that the Oosight and its applications were developed at the MBL," says Keefe. "The MBL is such a special and unique place. We had Shinya Inoué, Rudolf Oldenbourg, and our group of mammalian embryologists and clinicians, all working literally 25 feet from each other's labs. That's why this work was accomplished."
Journal citations:
Byrne, J.A., D.A. Pedersen, L.L. Clepper, M. Nelson, W.G. Sanger, S. Gokhale, D.P. Wolf, and S.M. Mitalipov (2007). Producing primate embryonic stem cells by somatic cell nuclear transfer. Nature 450: 497-502.
Liu, L., R. Oldenbourg, J.R. Trimarchi, and D.L. Keefe. 2000. A reliable, noninvasive technique for spindle imaging and enucleation of mammalian oocytes. Nature Biotech. 18: 223-225.
Adapted from materials provided by Marine Biological Laboratory.

Fausto Intilla

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