New cellular therapies benefits came to light as a result of powerful PET and SPECT imaging in a recent study reported in the April issue of the Journal of Nuclear Medicine. Researchers in Germany were able to observe the repair action of circulating progenitor cells (CPCs), immature blood-derived cells capable of developing into adult stem cells, as they successfully preserved healthy heart tissue and corrected blood flow imbalance within the heart.

Twenty-six patients took part in the randomized, placebo-controlled and double-blinded study. Following the recanalization of blocked coronary arteries (the surgical reopening or formation of new paths for blood flow), one group received an infusion of progenitor cells. FDG PET and 99mTc-tetrofosmine-SPECT were then used to image relative changes in myocardial perfusion (blood flow through the middle and thickest part of the heart) and glucose metabolism.

The results were compared with a control group that had undergone recanalization but did not receive CPCs. In the CPC group, normalization of glucose metabolism and coronary blood flow was seen in nearly 50 percent of the repaired artery segments.

“PET and SPECT are the only techniques capable of validating the metabolic changes we needed to observe in the heart once we had administered the progenitor cells,” said Kai Kendziorra, M.D., a specialist in Nuclear Medicine at the University of Leipzig in Leipzig, Germany. “The results shown by these imaging modalities provide the evidence needed to expand the use of CPC treatment.”

Earlier research has shown that when a patient’s progenitor cells are activated by growth factors, the result is increased cell division, which is vital to the tissue repair process. In this study, progenitor cells developed from circulating blood were also found to be capable of repairing dysfunctional—yet viable—myocardial tissue, a condition referred to as “hibernating myocardium.”

Kendziorra said he believes that in addition to assisting in monitoring and guiding treatment of heart patients, PET scans may also be helpful in selecting those who would profit the most from CPC administration.

“Early detection of hibernating myocardial tissue via noninvasive imaging modalities such as PET and SPECT will help us to assess a patient’s myocardial metabolism and blood flow,” he said. “Subsequent early coronary recanalization and CPC administration may lead to treatment-specific normalization and reduce the risk of cardiac events over longer periods.”

“For decades, nuclear medicine imaging has contributed functional assessment to the anatomical definition of the presence or absence of disease,” said Alexander J. McEwan, M.D., president of SNM. “Today molecular imaging is on the way to revolutionizing patient care—by integrating information about location, structure, function and biology—leading to a package of non-invasive imaging tools with enormous potential for improving patient care and outcomes.”

Co-authors of “Effect of Progenitor Cells on Myocardial Perfusion and Metabolism in Patients After Recanalizatoin of a Chronically Occluded Coronary Artery” include Henryk Barthel, Osama Sabri and Regine Kluge, Department of Nuclear Medicine; Sandra Erbs and Gerhard Schuler, Heart Center Leipzig GmbH; and Frank Emmrich, Institute of Clinical Immunology and Transfusion Medicine, all with the University of Leipzig, Leipzig, Germany; and Rainer Hambrecht, Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany and Heart Center Bremen, Bremen, Germany.

A group of researchers have discovered a gene in flies whose activity rises and falls depending upon the amount of protein and sugar in the insects’ diets. The findings, reported in the April issue of Cell Metabolism, might shed light on the way the insects’ bodies—and perhaps those of humans too—handle dietary extremes, including high-protein, low-carb diets like the Atkins, according to the researchers. These findings are also yielding new clues about the links between diet and life span.The gene, which the researchers call tobi (short for target of brain insulin), encodes an evolutionarily conserved a-glucosidase enzyme that converts stored glycogen into glucose.

“ This gene is activated by high protein and repressed by sugar,” said Michael Pankratz of Forschungszentrum Karlsruhe in Germany, who is now at the Fritz Lipmann Institute. “The question is: Why would the body need such a mechanism for releasing glucose under specific dietary conditions””

High-protein diets might hold one answer, Pankratz said. For instance, when people consume high-protein, low-carb diets, insulin is released, stimulating cells to take in sugar from the bloodstream. (Most people associate insulin with sugar, he said, but indeed insulin is also released in response to the amino acid building blocks of proteins.) Given that little to no sugar is coming in, this can lead to hypoglycemia, or low blood sugar. The body therefore needs a second mechanism to release glucose from glycogen. “We think this is what’s happening [in the flies],” he said. “It’s a sensitive mechanism for dealing with extreme dietary conditions.”

In mammals, one of the most important systems for controlling metabolism consists of the antagonistic actions of insulin and glucagon, the researchers explained. Upon high sugar intake, insulin is secreted by cells in the pancreas to maintain steady blood sugar levels. When blood glucose is low, glucagon is secreted by other pancreatic cells, causing the release of glucose from glycogen breakdown. The antagonism between insulin and glucagon is not strict, the researchers noted, since amino acids boost both insulin and glucagon secretion.

Earlier studies also identified insulin- and glucagon-like peptides in Drosophila fruit flies, but questions remained about how those signals act.

In the new study, by analyzing changes in gene activity in flies lacking insulin-producing cells, the researchers were led to tobi. They further found that tobi levels increased when flies consumed a protein-rich yeast paste and decreased when the insects ate a sugary concoction. That pattern of tobi expression is reminiscent of the hormone glucagon in mammals, the researchers noted, suggesting that the gene may be controlled by an analogous hormone.

Earlier studies had shown that flies lacking insulin-producing cells (which also express lower tobi levels) live longer. Indeed, the researchers found that this was true—but only in flies fed the high-protein diet.

Exactly what role tobi might play in life span will be a subject of further study, Pankratz said.

“The current study indicates that proteins may have a greater effect than sugars on insulin signaling, and evidence is growing that quality and not only quantity of calories taken in has an influence on life span,” the researchers said. “Therefore, teasing apart the relative contributions of dietary proteins and sugars in insulin signaling should prove insightful.”

“What is novel and exciting in the work of [Pankratz and colleagues] is the combination of gene regulation studies, endocrinology, and physiology in a model genetic organism whose genome and gene regulatory linkages can be readily compared to the human genome,” wrote Eric Rulifson of the University of California, San Francisco, in an accompanying commentary. “Given the accumulating parallels between the islet-like cells of Drosophila and the pancreatic islets of mammals, it would not be surprising if this homeostatic mechanism, and possibly others yet to be found, is evolutionarily conserved between flies and humans.”

An association between chronic inflammation and cancers of the prostate, colon, stomach and liver has been suggested recently by research. Scientists now at theNorthwestern University Feinberg School of Medicine report success in blocking an early step in metastasis of prostate cancer cells by interrupting the communication between the cancer cells and other cells that promote inflammation.Their success suggests new ways to control cancer spread and metastasis. The findings also provide an impetus to look more closely at existing inflammation-controlling drugs including non-steroidal anti-inflammatory drugs, cyclooxygenase inhibitors, antioxidants and statins. It is possible, says Dr. Paul Lindholm, that these widely available drugs could be used to control aggressive cancer cell growth and spread for these and other inflammation-associated cancers.

Dr. Lindholm presented results of the study on April 8 at the Experimental Biology 2008 meeting in San Diego. The presentation was part of the scientific program of the American Society for Investigative Pathology.

In earlier studies, Dr. Lindholm and his colleagues at Northwestern found that when compared to benign prostate tissues, prostate cancer tissue has a higher density of macrophages and the monocytes from which these immune system cells derive. These scavenger cells are vital to the regulation of immune responses and the development of inflammation. High grade and high stage prostate cancer tissues showed significantly increased numbers of macrophages compared to low grade and low stage tumors. When the researchers added monocyte-like cell lines or monocytes obtained from the blood of normal people to less aggressive prostate cancer cell lines, these cancer cells became more invasive, indicating that the cancer cells and the monocytes were indeed communicating with each other. But how?

In the study reported at Experimental Biology, the researchers demonstrated that the monocyte-like cells stimulate the cancer cells’ Nuclear Factor-kappaB, a gene regulating transcription factor able to stimulate gene activity. To test whether NF-kappaB activity was increasing the cancer cells’ movement and invasive activity, the researchers then introduced into the cancer cells biological inibitors that blocks NF-kappaB activity. The treatments that block NF-kappaB activity reduced the cancer cell movement and invasion through the basement membrane (a thin, delicate layer of connective tissue underlying the epithelium of many organs).

The researchers now plan to study the effects of macrophages and inflammation and NF-kappaB inhibiting treatments in vivo, in a specially designed mouse model of invasive prostate cancer. They also plan to extend these experiments to include drugs currently used in humans to control inflammation. If anti-inflammatory drugs block cancer cell NF-kappaB activity and spreading movement, as the researchers hope, these drugs may prove useful for patients whose cancers are discovered early but who are at risk for cancer spread. The results also could help identify biomarkers of early cancer, before it can be detected by current technology, and to monitor response to treatments designed to prevent cancer spread.

Alex Dajkovic, lead author on the paper and a former postdoctoral fellow at Johns Hopkins. He is now a researcher at Institut Curie in Paris.

A research team from Johns Hopkins has solved important puzzles concerning how certain proteins guide the reproduction of bacteria, discoveries that could lead to a new type of antibiotics.

In a recent study published in the journal Current Biology, the scientists reported how a belt-like structure called a Z ring, which pinches a rod-shaped bacterium to produce two offspring, can be disabled by a protein called MinC. By exploiting this vulnerability, the researchers said, pharmaceutical companies may find a way to fight infections that no longer respond to older medications.

“The potential medical applications of our discovery are significant,” said Alex Dajkovic, lead author of the paper. “Because the molecules involved in cell division are very similar in almost all bacteria, the process we uncovered provides a new target for the people who make antibiotics. This is extremely important because antibiotic resistance is on the rise, and many preventable deaths, especially in the developing world, are caused by bacterial infections.”

Denis Wirtz, professor of chemical and biomolecular engineering at Johns Hopkins.

Dajkovic helped make the discoveries as a postdoctoral fellow in the lab of Denis Wirtz, a professor of chemical and biomolecular engineering in Johns Hopkins’ Whiting School of Engineering. Dajkovic is now a researcher at Institut Curie in Paris.

Wirtz, who also is associate director of the Johns Hopkins Institute for NanoBioTechnology, noted that “most antibiotics target the ability of bacteria to build their cell walls or their ability to make proteins or DNA. With this paper, Alex and the rest of the team identified new molecular targets that could disrupt bacterial cell division. If the bacteria can’t reproduce, the infection will die.”

The researchers focused on the rod-shaped bacterium E. coli, commonly found in the human digestive tract, which serves as a model organism for study of basic bacterial processes. When these single-celled microbes want to multiply, a structure called the Z ring forms, then begins to tighten like a rubber band around each bacterium’s midsection. The Z ring helps to pinch the rod-shaped body into two microbial sausages that finally split apart to form two cells.

For about 20 years, researchers have known about the Z ring but have not understood precisely how it operated and why it always formed in the middle of rod-shaped cells. The main components of Z rings are filaments of a protein molecule called FtsZ

In the new journal article, the Johns Hopkins-led researchers were able to report for the first time that the changing of FtsZ threads from a liquid-like form to a more solid structure inside the cell is important for the formation of the Z ring. The team found that FtsZ threads weave themselves into a framework or scaffold that can hold all of the other molecules involved in the cell division process. The FtsZ filments are able to weave this tapestry, the researchers learned, because they tend to attract one another and interact along the length of each thread.

The team also discovered that MinC, another protein inside the bacterial cell, disrupts this process by liquefying the structure that is used to form a Z ring. “MinC blocks the attraction between FtsZ filaments along their lengths, and it also makes the filaments more fragile,” said Dajkovic. “This has the effect of shearing the weavings in the tapestry of the Z ring, which causes the whole structure to fall apart.”

MinC is most prevalent on the outer ends of the rod-shaped bacterial cell, the researchers said, and this explains why the Z ring always forms and splits the cell in the middle, where it is less likely to encounter its protein foe. The team members said this discovery also presents a promising opportunity: a new drug that mimics the effects of MinC could play havoc with the bacterial reproductive process and thereby put an end to an infection.

The findings resulted from a collaboration involving Dajkovic, whose background is in cell biology and biochemistry; Wirtz, whose expertise is in biophysics and engineering; and Sean X. Sun, a Johns Hopkins assistant professor of mechanical engineering who provided computational modeling of the cell division process. Wirtz and Sun were co-authors of the Current Biology paper, along with Ganhui Lan, a doctoral student in Sun’s lab, and Joe Lutkenhaus, a University Distinguished Professor in the Department of Microbiology, Molecular Genetics and Immunology at the University of Kansas Medical Center. Lutkenhaus was Dajkovic’s faculty advisor as a doctoral student.

A  group of small, non-coding RNA molecules may serve as a future marker to improve cancer staging and may also be able to convert some advanced tumors to more treatable stages, report a University of Chicago-based research team in the April 1, 2008, issue of the journal Genes & Development.Carcinomas are cancers that develop from epithelial tissue, which lines internal and external body surfaces. When normal cells are transformed into cancer cells, this epithelial tissue can take on the characteristics of embryonic tissue, known as mesenchymal tissue, which is comprised of unspecialized cells that will develop, as the embryo matures, into more specialized tissues.

That process also goes in reverse. Epithelial to mesenchymal transition (EMT) occurs, for example, during wound healing. In cancer, however, this process can produce invasive and mobile cells that can pass through membranes and travel to distant sites, where they seed new tumors.

“There are a bewildering numbers of pathways or stimuli that can either trigger EMT or reverse that process,” said study author Marcus E. Peter, PhD, professor in the Ben May Department for Cancer Research at the University of Chicago. “What we have identified is a master regulator of EMT that is probably controlled by many of these stimuli.”

Peter and colleagues showed that this master regulator consists of a specific group of microRNAs, a family called miR-200. MicroRNAs are tiny RNA molecules that have very important roles in gene regulation. They have multiple targets and act mainly by attaching themselves to specific sites in messenger RNA to prevent the production of proteins.

The authors studied a standard panel of 60 established human tumor cell lines representing nine different human cancers, as well as several specimens of human primary ovarian cancer. They showed that miR-200 was always present in epithelial (less invasive) and not in mesenchymal (more invasive) types of tumors.

“The importance of this finding is, first, that miR-200 may represent a good marker to stage cancer,” Peter said, and “second, that reintroducing miR-200 into late cancer cells could provide a new form of treatment, preventing these cells from going through EMT and becoming more invasive.”

Physicians already have a set of fairly reliable markers for carcinoma. Tumors with high levels of E-cadherin tend to be tightly tethered to nearby cells and less likely to break free and travel to other sites. Those with high Vimentin levels represent mesenchymal cells able to pass though other tissues.

Peter and colleagues found that miR-200 added mechanistic depth to those markers. Every tumor cell line the researchers tested that had the epithelial marker E-cadherin and not the mesenchymal marker Vimentin, had high amounts of miR-200. Every cell line with high Vimentin and no E-cadherin had no detectable miR-200.

“So we were able to show a complete correlation between miR-200 and E-cadherin/Vimentin expression,” Peter added.

The authors found that miR-200 microRNAs helped regulate EMT transition. They bind directly to non-coding regions in the RNA of ZEB1 and ZEB2, known blockers of E-cadherin transcription. Both ZEB proteins have previously been implicated in human malignancies, ZEB1 in aggressive colorectal and uterine cancers, and ZEB2 in advanced stages of ovarian, gastric and pancreatic tumors.

By inhibiting miR-200, Peter and his coworkers could induce EMT. More important, by introducing miR-200, they managed to activate production of E-cadherin protein and reverse tumors from a more-invasive mesenchymal into a less-invasive epithelial form.

“In a previous paper we found that another micro RNA, let-7, drives tumor progression at an earlier stage,” Peter said. “Let-7 appears to be a key player in preventing a cancer from becoming more aggressive. Now we want to figure out how these two micro RNAs work together to regulate carcinogenesis.”

Once they understand this process, they want to use these microRNAs to treat cancer. Both microRNA families have the connection to drug resistance as well as to cancer stem cells, sub-population of cancer cells that have self-renewal properties and the ability to give rise to new tumors that are more resistant to current therapy.

“Our aim is not only to make tumors less invasive by reintroducing let-7 and miR-200,” explained Peter. “We hope that we’ll make tumors more sensitive to drugs and be able to target the stem cell population, which gives tumors their renewal capacity.”

“The idea is a two-hit strategy,” Peter said, “hit them first with the microRNA and make those drug-resistant cells sensitive again, then hit them again with low levels of conventional chemotherapy.”

A group of researchers at UT Southwestern Medical Center have developed a simple and inexpensive method to screen small synthetic molecules and pull out a handful that might treat cancer and other diseases less expensively than current methods.

In one screen of more than 300,000 such molecules, called peptoids, the new technique quickly singled out five promising candidates that mimicked an antibody already on the market for treating cancer. One of the compounds blocked the growth of human tumors in a mouse model.

Antibodies are molecules produced by the body to help ward off infection. Natural and manmade antibodies work by latching onto very specific targets such as receptors on the surface of cells.

“Many new drugs being made today are antibodies, but they are extremely expensive to make. Financially, the U.S. health care system is going to have a difficult time accommodating the next 500 drugs being antibodies,” said Dr. Thomas Kodadek, chief of translational research at UT Southwestern and senior author of the study, which appears online and in an upcoming issue of the Journal of the American Chemical Society.

“Our results show that a peptoid can attack a harmful receptor in the body with the same precision as an antibody, but would cost much less to develop,” said Dr. Kodadek.

Peptoids are designed in the laboratory to resemble chains of natural molecules called peptides. Some peptides are used as medications, such as insulin or antibodies used to treat some cancers, but because the stomach digests them, most can’t be taken by mouth and must be injected.

By contrast, peptoids are resistant to the stomach enzymes that degrade natural peptides, so it is possible that they could be swallowed as a pill. Peptoids are much less expensive and easier to manufacture than antibodies, Dr. Kodadek said. They are also much smaller than antibodies, so they might be better at penetrating tumors or other disease sites, he said.

“Our technique is simple and fast, works with existing chemicals and needs no high-tech instrumentation, except for a microscope to detect the fluorescent colors we use to sort the compounds,” said Dr. D. Gomika Udugamasooriya, postdoctoral researcher in internal medicine and lead author of the study.

The new technique also has major advantages over traditional screening techniques that are commonly used to discover biologically active compounds from large collections. These screens, which require extensive automation, generally cost $40,000 or more; the new method can be conducted for less than $1,000.

The researchers screened about 300,000 peptoids to see which ones would interact with VEGFR2, a type of molecule on the surface of human cells. VEGFR2 is essential in creating new blood vessels through interaction with the hormone VEGF, which is normally a helpful process but is harmful to the body when the new blood vessels are nourishing a growing tumor.

A commercially produced antibody is used to treat some cancers by blocking the VEGF-VEGFR2 interaction and thus starving the tumor, but it costs a patient about $20,000 a year, Dr. Kodadek said.

The new screening technology involves hundreds of thousands of peptoids, bound to tiny plastic beads. In the study, the cells with VEGFR2 were labeled to fluoresce red and those lacking VEGFR2 were labeled to fluoresce green. After exposing the beads to the mixture of cells, the beads were examined under a fluorescent microscope. Those bound to red cells — the ones with VEGFR2 — were collected.

This screen, which took a couple of days, isolated five peptoids out of approximately 300,000 screened, showing that the process was an effective way to quickly narrow down a search, Dr. Kodadek said.

The researchers further tested one of the five peptoids that bound most tightly to VEGFR2 and found that it blocked VEGFR2’s action in cultured cells. When they gave it in low doses to mice with implanted human bone- and soft-tissue cancer, the peptoid slowed the growth of the tumors and reduced the density of blood vessels leading to them.

“This new technique of rapidly isolating biologically active peptoids offers a way to hasten the drug-discovery process and may ultimately benefit patients by providing them with new therapies at a fraction of the cost of current drugs,” Dr. Kodadek said.

Other UT Southwestern researchers who participated in the study were general surgery resident Dr. Sean Dineen and Dr. Rolf Brekken, assistant professor of surgery.

The work was supported by the National Heart, Lung and Blood Institute and The Welch Foundation.

A new research study discovered that scrapie can be transmitted to lambs through milk. The study was published in the online open access journal BMC Veterinary Research. The study provides important information on the transmission of this prion-associated disease and the control of scrapie in affected flocks. Scrapie is a fatal neurodegenerative disease of sheep and goats. Clinical signs include itchiness, head tremor, wool loss and skin lesions as well as changes in behaviour and gait.Timm Konold and colleagues from the Veterinary Laboratories Agency in Weybridge, UK, investigated the transmission of scrapie by feeding milk from scrapie-affected ewes to lambs that are genetically susceptible to contracting scrapie. The researchers were looking for the presence of the prion protein, PrPd, which is associated with the disease.

Eighteen lambs were fed milk from scrapie-affected ewes. Three of these lambs were culled and two were found to have PrPd in intestinal tissues. The prion protein was also detected in lymphoid tissue of the gut of the surviving lambs and in some control lambs mixed with the scrapie milk recipients after weaning. This suggested that scrapie milk recipients were able to shed the infectious agent and infect other lambs. There was no sign of PrPd in tissue samples from a control group of 10 lambs(one culled and the rest alive), which were housed in the same building but fed milk from healthy ewes. The research will continue, to see whether the lambs with PrPd develop the disease as they get older.

This work raises the possibility that other prion diseases could be transmitted in sheep via milk although it should have no direct implications for human health. Scrapie has been found in sheep and has not been shown to be transmissible to humans. BSE has not been found naturally in sheep and occurrence in sheep in the UK is considered to be unlikely. This research adds to our understanding of the transmission of prion diseases in sheep and would help to inform measures needed to protect human health if BSE were ever to be found in sheep.

References on Prion Disease from Milk1. Evidence of scrapie transmission via milk
Timm Konold, S. Jo Moore, Susan J. Bellworthy, and Hugh A. Simmons
BMC Veterinary Research (in press)

A group of scientists at Yale have now provided a glimpse of the ancient mechanism that helped diversify our genomes; it illuminated a relationship between gene processing in humans and the most primitive organisms by creating the first crystal structure of a crucial self-splicing region of RNA.

The genes of higher organisms code for production of proteins through intermediary RNA molecules. But, after transcription from the DNA, these RNAs must be cut into pieces and patched together before they are ready for translation into protein. Stretches of the RNA sequence that code for protein are kept, and the intervening sequences, or introns, are spliced out of the transcript.

This work, published in Science, highlights a 16-year quest by Anna Marie Pyle, the William Edward Gilbert Professor of Molecular Biophysics & Biochemistry at Yale, and her research team into the nature of “group II” introns, a particular type of intron within gene transcripts that catalyzes its own removal during the maturation of RNA.

Group II introns are found throughout nature, in all forms of living organisms. Although much has been learned about their structure and how they work through biochemical and computational analysis, until now there have been no high-resolution crystal structures available. The resulting images have provided both confirmation of the earlier work and new information on the three-dimensional structure of RNA and the mechanism of splicing.

“One of the most exciting aspects of this work was that we did not need to do anything disruptive to these molecules to prepare them for structural analysis,” said Pyle. “The molecules showed us their structure, their active site and their activity — all in a natural state. We were even able to visualize their associated ions.”

According to Pyle, the crystal structure revealed some unexpected features — showing two sections that were most implicated as key elements of the active site and strengthening a theory that the process of splicing in humans “shares a close evolutionary heritage” with ancient forms of bacteria.

Looking to future applications of the work, Pyle said, “Group II introns hold promise in the future as agents of gene therapy. A free intron is an infectious element that is special because it targets DNA sites very specifically. We hope that further knowledge of these structures may lead to the development of new genetic tools and therapeutics.”

Citation: Science 320 , 77-82 (April 4, 2008). [DOI: 10.1126/science.1153803]

CHICAGO – Neurons which were grafted into the brain of a patient with Parkinson’s disease fourteen years ago have developed Lewy body pathology, the defining pathology for the disease, according to research by Jeffrey H. Kordower, PhD, and associates and published in the April 6 issue of Nature Medicine.

These findings suggest that Parkinson’s disease is an ongoing process that can affect cells grafted into the brain in the same way the disease affects host dopamine neurons in the substantia nigra of the brain, according to Kordower, who is the lead author of the study and a neuroscientist at Rush University Medical Center.

“These findings give us a bit of pause for the value of cell replacement strategy for Parkinson’s disease,” said Kordower.  “We still need to vigorously investigate this approach among the full armament of surgically-delivered Parkinson’s disease therapies. While it is not clear to us whether the same fate would befall stem cell grafts, the next generation of cell replacement procedures, this study does suggest that grafted cells can be affected by the disease process.”

The collaborative research study described in the article involves Rush, Mt. Sinai School of Medicine, New York, and the University of South Florida, Tampa, In it, individuals with Parkinson’s disease received fetal cell transplants to reverse the loss in the brain of striatal dopamine.

The individual described in this article was a woman with a 22-year history of Parkinson’s disease who underwent transplantation in 1993. After transplantation she experienced improvements in disease symptoms as measured by the Unified Parkinson Disease Rating Scale (UPDRS) and required substantially lower doses of antiparkinsonian medications. Her UPDRS scores remained improved into1997, but by 2004, she experienced progressive worsening of Parkinson’s disease symptoms. She died in 2007 and her brain and that of two other patients in the study were comprehensively processed and analyzed. She had the longest survival after transplantation that had been reported to date among this study’s participants.

Double-blind, sham-controlled studies that followed did not establish clinical benefit although significant improvement was observed in a subpopulation of patients. Post mortem studies of individuals in these studies showed a robust survival of grafted neurons, suggesting that the cells were not affected by Parkinson’s disease as Kordower explains “Because Parkinson’s disease pathology progresses over decades, we think that the individuals did not live long enough for the Parkinson’s disease pathology to develop in the grafted cells.”

Scientists have long debated whether Parkinson’s disease results from an acute insult or event, or whether it is an ongoing pathological process that continues to affect healthy neurons, according to Kordower. This research indicates that mechanisms and molecules responsible for initiating the degenerative process are still present at a late stage and are capable of affecting grafted neurons.  In addition, the processes that destroy dopamine neurons are not restricted to the midbrain.

“The findings also suggest that there may be either a pathogenic factor in the brain that affects dopamine producing neurons or a pathological process that can spread from one cellular system to another,” said Kordower.  “These findings have striking implications for understanding what causes PD and the potential for cell replacement strategies to reverse the motor symptoms.”

The study is available online at http:/www.nature.com/naturemedicine

These dopamine ‘mother cells’ which produce the neurons affected by Parkinson’s disease have been identified by scientists, according to new research published in the journal Glia.The new discovery could pave the way for future treatments for the disease, including the possibility of growing new neurons, and the cells which support them, in the lab. Scientists hope these could then be transplanted into patients to counteract the damage caused by Parkinson’s.

The new study focuses on dopaminergic neurons – brain cells which produce and use the chemical dopamine to communicate with surrounding neurons. The researchers found that these important neurons are created when a particular type of cell in the embryonic brain divides during the early stages of brain development in the womb.

If a person suffers from Parkinson’s disease, it is the depletion of these dopaminergic neurons and the associated lack of dopamine in the body which causes chronic and progressive symptoms including tremors, stiff muscles and slow movement.

The international research team used mouse models in the laboratory to examine the early stages of brain formation. They discovered that dopaminergic neurons are formed by precursor cells identified as ‘radial glia-like cells’ by the scientists because of their similarity to radial glia cells which are already known to build other parts of the brain.

The scientists hope that this discovery could, in the future, lead to new therapies which would use these radial glia-like cells derived from patients’ own stem cells to grow replacement neurons in the lab, which could then be transplanted into the brain to replace the neurons they have lost.

One of the authors of the paper, Dr Anita Hall from Imperial College London’s Department of Life Sciences, explains the potential of the team’s findings: “You could call these radial glia-like cells the stem cells of this part of the brain – they contain all the information needed to create and support the young dopamine-producing neurons which are essential for important human functions including motor activity, cognition and some behaviours.

“Now that we understand how these neurons are produced, we hope that this knowledge can be used to develop novel therapies including techniques to create replacement neurons for people with Parkinson’s which could be implanted into the brain to bolster their vital supplies of dopamine.”

Dr Hall adds, however, that more research is needed to work out how exactly these glia-like cells could be used: “Using these mother cells to grow new neurons in the lab which are fit to be transplanted into humans will be complicated, and extensive further research is needed before this becomes a clinical reality. For example, we’re not yet sure whether the mother cells themselves would need to be transplanted too, in order to facilitate successful dopamine production in the brain of a Parkinson’s patient,” she said.

In the UK, one in every 500 people – approximately 120,000 individuals – has Parkinson’s disease. Around 10,000 people are diagnosed with the disease every year. The symptoms of Parkinson’s disease usually appear when about 80% of the brain’s dopamine has been lost. The level of dopamine in the brain then continues to fall slowly over many years. The reasons why the loss of dopamine occurs in the brains of people with Parkinson’s is currently unknown.

Many scientists have tried for decades to understand the mechanism that allows these channels to open. Using cryo-electron microscopy, in which samples frozen at extremely low temperatures are examined under an electron microscope, some researchers obtained images of the closed ion channel. More recently, others used X-ray crystallography to image the closed-channel conformation. This technique involves crystallizing the protein, creating a lattice that reveals many details of its three-dimensional structure.

But until the Illinois team developed a new method for probing the interior of the open channel, no studies had been able to infer the structure of the open channel conformation in a living cell. The Illinois team was able to do this by exploiting electrical properties of these membrane proteins.

Much like the flow of electrons through an electrical wire, the flow of ions through a cell membrane is a current. In the 1970s, two German researchers developed a technique for measuring the current through a single ion channel, an innovation (known as the patch-clamp technique) that won them a Nobel Prize in 1991. Claudio Grosman, a professor of molecular and integrative physiology at Illinois, and Gisela D. Cymes, a postdoctoral associate in his lab, adopted this technique, and predicted that they could use it as a tool for what they call “in vivo, time-resolved structural biology.”

In a study published in 2005, the Grosman lab showed that ionizable amino acids (that is, those that may alternately be charged or neutral) can be engineered into the inner lining of the channel pore. These changes to the amino acid sequence alter the current, revealing the structure of the open-channel conformation in unprecedented detail.

The neurotransmitter acetylcholine is an essential chemical communicator, carrying impulses from neurons to skeletal muscle cells and many parts of the nervous system. Now researchers at the University of Illinois have painstakingly mapped the interior of a key component of the relay system that allows acetylcholine to get its message across. Their findings, which appear in the current issue of Nature Structure & Molecular Biology, reveal how the muscle nicotinic acetylcholine receptor responds to a burst of acetylcholine on the surface of a cell.

The muscle nicotinic receptor is a neurotransmitter-gated ion channel. This “gate” regulates the flow of information, in the form of charged particles, or ions, across the cell membrane. Although normally closed, when the ion channel encounters acetylcholine – or nicotine – on the surface of the cell the interaction causes the gate to open, allowing positively charged ions (called cations) to flow into the cell.

“As the ionizable amino acids bind and release protons from the watery environment, the pore gains or loses a positive charge that interferes with the normal flow of cations through the channel,” Grosman said.
After analyzing the data, Grosman’s team demonstrated that the discrete changes in current reflect the position of each mutated amino acid in the channel and the extent to which water molecules penetrate the membrane protein.

This approach allowed Grosman’s team to map the relative position of every amino acid that formed the ion channel.

The new study extends this work to more distant portions of the protein.

After comparing these findings to direct studies of the structure of the closed channel, Grosman concluded that the conformational changes that allow the channel to open are quite subtle. The five subunits that make up the protein channel do not rotate or pivot dramatically when opening the gate.

“There are many good reasons why I think a subtle conformational change is advantageous from an evolutionary point of view,” Grosman said.

Muscle nicotinic receptors must respond to acetylcholine with staggering speed, opening within microseconds of their exposure to the neurotransmitter.

“These ion channels are meant to be quick,” he said. “If they are too slow, we have disease.”

Grosman said that the approach developed in his lab is the first to allow scientists to infer the structure of an ion channel in its open conformation as it functions in a living cell.

“I know when the protein is open, because in single-molecule experiments the distinction between open and closed conformations is simple; the channel either passes a current or not,” he said.

In a living cell the protein responds, in measurable ways, to changes in its structure and environment, he said. “It’s not frozen at super low temperatures. It’s not in a crystalline lattice. The cells are alive at the beginning of the experiment and when we finish the experiment, the cells keep living.”

In these microscopic images of cells, the white areas indicate the presence of enzymes. The enzymes in images A and C are distributed throughout the cytoplasm because these cells were grown in the presence of purines. In contrast, the enzymes in images B and D occur in small clusters because these cells were grown in the absence of purines.

A group of Penn State scientists are the first to observe in living cells a key step in the creation of adenine and guanine, two of the four building blocks that comprise DNA. Also called purines, the two building blocks are essential for cell replication. The findings, which will be published in the 4 April 2008 issue of the journal Science, could lead to new cancer treatments that prevent cancer cells from replicating by interfering with their abilities to make purines.

The group used cervical cancer cells–which have an increased demand for purines due to their rapid rates of replication–to demonstrate that a group of six enzymes is involved in the creation of purines. “Our research shows that these enzymes form a cluster prior to purine formation,” said Erin Sheets, an assistant professor of chemistry and a collaborator on the project.

Although other researchers had, in the past, studied the enzymes individually in test tubes, no one, until now, had examined the group of enzymes together in living cells. “This is the first time that anyone has used the appropriate technology to look for this kind of complex in a living cell,” said the team’s leader Stephen Benkovic, Evan Pugh Professor of Chemistry and holder of the Eberly Family Chair in Chemistry.

These cells, which were grown in the absence of purines, contain enzymes that are labeled with fluorescent proteins. The bright areas represent enzyme clusters.

Postdoctoral associates Songon An and Ravindra Kumar, from the Benkovic group, studied the enzyme clusters using a technique called fluorescence microscopy, in which fluorescent proteins are attached to molecules of interest and viewed under a special microscope. According to Sheets, the technique makes it easier to observe specific molecules in a cell. “It’s like giving a bright orange helmet to your favorite football player so you can more easily monitor his actions,” she said.

The researchers attached fluorescent proteins to the enzymes of cells grown in the presence and absence of purines. They found that in the absence of purines, enzymes formed clusters at much higher rates, suggesting that they play a role in the creation of new purines. In contrast, cells also can produce purines by recycling old purine material. Owing to this salvage process, cells do not always need enzyme clusters; indeed, cluster formation was not observed in cells that were grown in the presence of purines. In a key experiment, the researchers were able to influence the association and dissociation of the enzyme cluster by changing the cells’ exposure to purines.

Not all of the cells that were grown in the absence of purines contained enzyme clusters. “We think that the enzymes form clusters only when a cell needs purines, and that happens when a cell is required to replicate its DNA at a certain stage in its cell cycle,” said Sheets. “Since each of our samples contain cells at different stages of the cell cycle, we did not expect all of them to be actively replicating their DNA. Therefore, we weren’t surprised to find that some of our cells did not contain enzyme clusters.”

Because purines are necessary for DNA replication and, ultimately, for cell replication, the ability to halt purine synthesis could prove to be a valuable method for treating cancer. “Cancer cells have very high demands for purines,” said Benkovic. “If we can find a way to disrupt the formation of this particular enzyme cluster, it could become a potential new target for cancer therapy.”

Pregnant and lactating rats fed on a diet of hydrogenated fat during pregnancy and lactation had babies who were fatter than rats fed a normal diet, according to research published in Lipids in Health and Disease. The unhealthy diet has deleterious consequences even after the fats were removed from the diet and has links to insulin production.“We know that foetal growth is influenced by the mother’s nutritional status,” explained Brazilian nutritionist Luciana Pisani. ”The nutritional conditions during pregnancy has a major role in the metabolic and hormonal interactions between the mother’s body, placenta and foetus. To date only a few studies have looked at the effects on trans fatty acids during pregnancy and lactation on the metabolism of offspring in adulthood. We found that the fatty content of the babies’ bodies increased when the mothers were fed the hydrogenated fat rich diet and this could be traced to the gene expression of adipokines.”

In an investigation to examine whether feeding pregnant and lactating rats hydrogenised fats rich in trans fatty acids, increased the fat content in carcass, the researchers found that their metabolic rate dropped dramatically. Interestingly young rats that were fed a normal diet after they were born ate less and weighed less even though their mothers had been eating the trans fatty acids while pregnant. The gene expression of adipokines was also examined in relation to insulin production.

The offspring were weighed weekly and exposure to the trans-fatty acid enriched diet after weaning led to a 40% increase in body fat content for the young rats. Rats whose mothers were fed the trans fatty acids and continued to eat the fats into adulthood had the highest metabolic efficiency. The same rats increased their insulin production.

Pisani continued, “Fats play a fundamental role in foetal development and changes in dietary fatty acids has important implications for foetal and postnatal development. Heavy ingestion of very hydrogenated fats rich in trans fatty acids increases risk of cardiovascular diseases and reduces insulin sensitivity and so leads to type 2 diabetes. We need to investigate this further as this has important implications for people’s own diets, especially pregnant women.”

ReferencesHydrogenated fat diet intake during pregnancy and lactation modifies the PAI-1 gene expression in white adipose tissue of offspring in adult Lipids in Health and Disease (in press)

A genetic disorder that can cause a fatal rise in body temperature in some patients undergoing general anesthesia may hold the key to a cure for heat stroke, according to research published in the April 4 edition of the journal Cell. The findings further suggest that antioxidants, like those currently being tested to protect the lungs of cystic fibrosis patients, may also protect those genetically prone to suffer heat stroke.According to the current study authors, all U.S. operating rooms should, but do not always, have a supply of a drug called dantrolene on hand, which causes muscles to relax by a unique mechanism. Dantrolene is a must in the rare cases where patients receiving general anesthesia unexpectedly go into whole-body muscle contractions as part of an inherited condition called malignant hyperthermia (MH). Occurring in one in about 10,000 adult patients undergoing general anesthesia, and more frequently in children, MH reactions alter the acid content of blood and tissues, increase heart rate, cause muscle rigidity and trigger a rapid rise in body temperature up to 112° F. Kidney failure and potentially fatal heart arrhythmias can result in the worse cases. MH received national news coverage recently because of the unfortunate case of an 18-year-old Florida high school senior, Stephanie Kuleba, whose death was apparently caused by a fatal reaction to anesthesia during corrective surgery.

Researchers are also interested in MH because it may be caused by the same biochemical pathways as heat stroke, a much more common condition that has caused more U.S. deaths than hurricanes, tornadoes, floods and earthquakes (8,000) together since 1979, according to the Centers for Disease Control and Prevention. Given the number of troops currently operating in deserts, the U.S. military has a keen interest in the work. For the first time, researchers at four universities and in the U.S. Army have provided strong evidence that the genetic and protein defects that cause MH also contribute to the development of heat stroke. They have also identified mechanisms by which both conditions may damage cells.

”Along with cardiac abnormalities, heat stroke is a major culprit in unexpected sudden deaths of otherwise fit, young athletes and soldiers,” said Robert T. Dirksen, Ph.D., associate professor of Pharmacology and Physiology at the University of Rochester Medical Center. “With a better knowledge of these mechanisms, we can begin to better diagnose and treat both disorders, and hopefully, save some lives,” said Dirksen, a co-author on the study.

The Perfect Switch

To drive life processes, human cells expend tremendous energy to continually push positively charged calcium ions both out of cells, and into internal calcium storage compartments. This creates charge/calcium gradients across cell membranes, a powerful source of potential energy. Cells harness this energy to send nerve signals, regulate genes and trigger muscle contraction. Muscle movement in the body is regulated by precisely controlled increases in calcium ion concentration acting as a biochemical switch.

Going into the current study, the team knew from the literature that a genetic mutation – a small, random mistake in the genetic code – causes MH susceptibility in humans. They also knew that the mutation was located in a gene that codes for ryanodine receptor proteins. These calcium channels provide a pathway for calcium in the internal storage compartment, the sarcoplasmic reticulum, to be released into the muscle cell to cause contraction.

For the current project, researchers genetically engineered mice with a mutation seen in human MH disease. They found that these mice indeed exhibited full-body contractions that lead to death during exposure to anesthesia (e.g. halothane), a hallmark of malignant hyperthermia. Unexpectedly, the mice were also found to experience similar, life-threatening episodes during brief exposure to environmental heat stress (105oF). These results establish a surprising connection between altered ryanodine receptor activity and heat stroke, with the mutated calcium channel being more likely to exhibit uncontrolled calcium release and muscle contraction in response to heat.

Furthermore, the team demonstrated that increased calcium ion leakage from mutated ryanodine receptors during heat stress caused a profound increase in free radical production. Also called reactive oxygen species (ROS) and nitrogen species (RNS), free radicals are highly reactive molecules that can destroy sensitive cell components and hasten cell death. Free radicals are largely created as a side effect when structures within all human cells, the mitochondria, use oxygen to turn food into an energy-storing molecule called adenosine triphosphate (ATP). To drive ATP production, electrons are passed along a chain of enzymes within the mitochondria. When some of these electrons are not passed along effectively, they combine with oxygen and nitrogen to form free radicals. Disease processes tend to create far higher levels of free radicals than the body’s naturally occurring antioxidants can mop up.

In the current study, results showed that free radical production in muscle nearly doubled in the genetically altered mice, and that it rose even more during heat stress. Researchers also found that the increase in free radicals results from increased calcium leak from the mutated calcium channels in the sarcoplasmic reticulum, potentially driving increased ROS/RNS production by nearby mitochondria. In addition, the increase in ROS/RNS levels were in turn found to travel back to, and further alter, mutated ryanodine receptor calcium channels.

This “vicious feed-forward cycle” caused the calcium leak to further worsen, the calcium channels to become extremely heat sensitive and muscles to contract uncontrollably in response to both anesthesia and heat. Uncontrolled contractions can break apart muscle cells, releasing toxic cellular metabolites into the bloodstream that ultimately trigger kidney failure and throw the heartbeat out of rhythm. Even in the absence of such acute events, increased oxidative stress in the muscle of mutant mice over the long term was also found to distort the shape of mitochondria and weaken muscle contraction (myopathy).

Most importantly, simply including an antioxidant, N-acetylcysteine (NAC), in the animal’s water supply resulted in a marked reduction in sensitivity to heat stress, improved mitochondrial health and restoration of muscle function in aged mice. NAC is currently in phase 2 human clinical trials for patients with cystic fibrosis, where disease creates free radicals that damage lung tissue.

Researchers from the Medical Center, the Baylor College of Medicine and CeSI Centro Scienze dell’Invecchiamento Universit degli Studi G in Italy collaborated on the paper. Along with Dirksen, the Rochester effort was led by Ann Rossi and Sanjeewa Goonasekera, Ph.D. in the Department of Pharmacology and Physiology. Susan L. Hamilton, Ph.D., chair of the Department of Molecular Physiology & Biophysics at Baylor, was the corresponding author. Although not authoring institutions on the current paper, the Uniform Services University of the U.S. Army and Harvard University also participated in the work through a related grant from the National Institutes of Health.

“We found that destructive cycles of calcium leakage and excess free radical production damage mitochondria and contribute to the deterioration of muscle function in aged animals,” Dirksen said. “In successfully constructing the first mouse model of human MH, we unwittingly generated the first animal model of heat stroke that will undoubtedly be tremendously useful in better understanding these disorders and in accelerating the design of safe and effective treatments for both conditions.”

“Malignant hyperthermia syndrome, a potentially fatal inherited disorder, is most often ‘triggered’ by certain gas anesthetics and the paralyzing drug succinylcholine,” said Henry Rosenberg, M.D., president of the Malignant Hyperthermia Society of the United States and professor of anesthesiology at Mount Sinai School of Medicine, N.Y. “In the naturally occurring animal model, certain breeds of swine, the syndrome is also precipitated by environmental conditions. It has long been debated as to whether some cases of heat stroke and exercise-induced muscle breakdown in humans are related to malignant hyperthermia as well. This study defines a biochemical pathway that might very well clarify the relationship between anesthesia-induced malignant hyperthermia and heat stroke. This elegant study, using modern molecular techniques, opens new avenues for the study of the not-uncommon problem of heat stroke and exercise-induced muscle breakdown and the risk for malignant hyperthermia.”

Choline is an essential nutrient found in foods such as eggs, is associated with a 24 percent reduced risk of breast cancer, according to a study supported by a grant from the U.S. National Institutes of Health (NIH), to be published in The FASEB Journal’s print issue in June.(1) This study adds to the growing body of evidence that links egg consumption to a decreased risk of breast cancer.In this new case-control study of more than 3,000 adult women, the risk of developing breast cancer was 24 percent lower among women with the highest intake of choline compared to women with the lowest intake. Women with the highest intake of choline consumed a daily average of 455 mg of choline or more, getting most of it from coffee, eggs and skim milk. Women with the lowest intake consumed a daily average of 196 milligrams or less.

“Choline is needed for the normal functioning of cells, no matter your age or gender,” says Steven H. Zeisel, MD, PhD, University of North Carolina, who is an author of the study and a leading choline researcher. “Increasing evidence shows that it may be particularly important for women, particularly those of child-bearing age.”

Only ten percent of Americans currently meet the recommended intake for choline, identifying a need to increase choline intake across the population.(2) According to the Institute of Medicine, adequate choline intake is 550 milligrams per day for men and breastfeeding women, 425 milligrams per day for women, and 450 milligrams per day for pregnant women.(3) One egg contains 125.5 milligrams of choline, or roughly a quarter the recommended daily supply, making eggs an excellent source of this essential nutrient.(4) Choline is found exclusively in the egg’s yolk. Other top food sources of choline include liver, wheat germ and cauliflower.

“While choline is an essential nutrient to the human diet, most people haven’t even heard of it,” says Gerald Weissmann, MD, Editor in Chief of The FASEB Journal and research professor of medicine and director of the Biotechnology Study Center at the New York University School of Medicine. “Given that in the U.S. there is a real need to understand how much choline we require in our diet, we hope that research, education and awareness about choline will increase as a result of this study published in The FASEB Journal.”

Eggs and Decreased Risk of Breast Cancer:

Two previously published studies, supported by NIH grants, have shown that women who eat eggs have a lower risk of developing breast cancer:

• A study published in 2003 by researchers at Harvard University found that women who reported higher consumption of eggs, vegetable fat and fiber during adolescence had a smaller risk of developing breast cancer as adults. Specifically, eating one egg per day was associated with an 18 percent reduced risk of breast cancer.(5)
• A study of Chinese women published in Cancer Epidemiology, Biomarkers & Prevention in 2005 showed that those who consumed the most fruit, vegetables and eggs were significantly less likely to have breast cancer. For those that reported eating at least six eggs per week, the risk of developing breast cancer was 44 percent lower than for those who ate two or less eggs per week.(6)

Other Benefits of Choline:

In addition to playing a role in the normal functioning of all cells, including brain and nerve function, liver metabolism and the transportation of nutrients throughout the body, choline has been shown to:

• Prevent Birth Defects: According to population-based research, infants from mothers whose diets were deficient in choline were four times more likely to have neural tube defects such as spina bifida. This increased risk was observed even when other nutrients that help prevent birth defects, such as folic acid, were in adequate supply.(7)
• Improve Memory: Research suggests that choline is essential for proper fetal and infant brain development. It appears that choline affects the areas of the brain responsible for memory function and life-long learning ability.(8)
• Reduce Heart Disease Risk: Choline, like folate, is involved in breaking down homocysteine, an amino acid in the blood that may be associated with an increased risk of heart disease. In fact, research shows that choline deficiency results in increased homocysteine levels.(9) This may help to explain why 30 years of research have shown that healthy adults can consume eggs without increasing their risk of heart disease.(10)

References(1) Xu X, et al. Choline metabolism and risk of breast cancer in a population-based study. The FASEB Journal, published online on January 29, 2008.

(2) Jensen HH, et al. Choline in the diets of the US population: NHANES, 2003-2004, Iowa State University (presented at Experimental Biology 2007, Washington DC).

(3) Dietary Reference Intakes, Institute of Medicine of the National Academies, National Academies Press, Washington, DC, 2006.

(4) U.S. Department of Agriculture. USDA database for the choline content of common foods, U.S. Department of Agriculture, Beltsville, Maryland, 2004.

(5) Frazier AL, et al. Adolescent diet and risk of breast cancer. Breast Cancer Res 2003; 5: R59-R64.

(6) Shannon J, et al. Food and botanical groupings and risk of breast cancer: A case-control study in Shanghai, China. Cancer Epidemiol Biomarkers Prev 2005; 14 (1): 81-90.

(7) Shaw GM, et al. Periconceptional dietary intake of choline and betain and neural tube defects in offspring. Am J Epidemiol 2004; 160: 102-109.

(8) Zeisel SH. Nutritional importance of choline for brain development. J Am Col Nutr 2004; 23: 621S – 626S.

(9) Da Costa K-A, et al. Choline deficiency in mice and humans is associated with increased plasma homocysteine concentration after a mehtionine load. Am J Clin Nutr 2007; 85:1275-1285.

(10) Lee A and Griffin B. Dietary cholesterol, eggs and coronary heart disease risk in perspective. Nutrition Bulletin (British Nutrition Foundation) 2006: 31: 21-27.