Josh: This is certainly an interesting study. I suppose the primary question I have is why do cells decrease the expression of the lysosomal receptors with age? Knowing that would be helpful, I think not only for aging and neurodegenerative research, but also for cancer research. Too bad this won’t really be a realistic treatment in its current state…however, perhaps a drug could be used to increase expression.

As people age, their cells become less efficient at getting rid of damaged protein — resulting in a buildup of toxic material that is especially pronounced in Alzheimer’s, Parkinson’s disease, and other neurodegenerative disorders.

Now, for the first time, scientists at the Albert Einstein College of Medicine of Yeshiva University have prevented this age-related decline in an entire organ — the liver — and shown that, as a result, the livers of older animals functioned as well as they did when the animals were much younger. Published in the online edition of Nature Medicine, these findings suggest that therapies for boosting protein clearance might help stave off some of the declines in function that accompany old age. The study’s senior author was Dr. Ana Maria Cuervo, associate professor in the departments of developmental & molecular biology, medicine and anatomy & structural biology at Einstein.

The cells of all organisms have several surveillance systems designed to find, digest and recycle damaged proteins. Many studies have documented that these processes become less efficient with age, allowing protein to gradually accumulate inside cells. But aging researchers continue debating whether this protein buildup actually contributes to the functional losses of aging or instead is merely associated with those losses. The Einstein study was aimed at resolving the controversy.

One of these surveillance systems — responsible for handling 30 percent or more of damaged cellular protein — uses molecules known as chaperones to seek out damaged proteins. After finding such a protein, the chaperone ferries it towards one of the cell’s many lysosomes — membrane-bound sacs filled with enzymes. When the chaperone and its cargo “dock” on a receptor molecule on the lysosome’s surface, the damaged protein is drawn into the lysosome and rapidly digested by its enzymes.

In previous work, Dr. Cuervo found that the chaperone surveillance system, in particular, becomes less efficient as cells become older, resulting in a buildup of undigested proteins within the cells. She also detected the primary cause for this age-related decline: a fall-off in the number of lysosomal receptors capable of binding chaperones and their damaged proteins. Could replenishing lost receptors in older animals maintain the efficiency of this protein-removal system throughout an animal’s lifespan and, perhaps, maintain the function of the animal’s cells and organs as well?

To find out, Dr. Cuervo created a transgenic mouse model equipped with an extra gene — one that codes for the receptor that normally declines in number with increasing age. Another genetic manipulation allowed Dr. Cuervo to turn on this extra gene only in the liver and at a time of her choosing, merely by changing the animals’ diet.

To keep the level of the receptor constant throughout life, Dr. Cuervo waited until mice were six months old (the age that the chaperone system’s efficiency begins to decline) before turning on the added receptor gene. When the mice were examined at 22 to 26 months of age (equivalent to approximately 80 years old in humans), the liver cells of transgenic mice digested and recycled protein far more efficiently than in their normal counterparts of the same age — and, in fact, just as efficiently as in normal six-month old mice.

Does maintaining efficient protein clearance in liver cells of an older animal translate into better functioning for the liver as a whole? Since a key function of the liver is metabolizing chemicals, Dr. Cuervo answered this question by injecting a muscle relaxant into very old transgenic mice and very old normal mice. The very old transgenic mice metabolized the muscle relaxant much more quickly than very old normal mice and at a rate comparable to young normal mice.

“Our study showed that functions can be maintained in older animals so long as damaged proteins continue to be efficiently removed — strongly supporting the idea that protein buildup in cells plays an important role in aging itself,” says Dr. Cuervo. “Even more important, these results show that it’s possible to correct this protein ‘logjam’ that occurs in our cells as we get older, thereby perhaps helping us to enjoy healthier lives well into old age.”

Dr. Cuervo next plans to study animal models of Alzheimer’s, Parkinson’s and other neurodegenerative brain diseases to see whether maintaining efficient protein clearance in the brain might help in treating them. “Most people with these conditions are born with a mutation that gives rise to defective proteins, but they don’t experience symptoms until later in life,” says Dr. Cuervo. “We think that’s because their protein-clearance systems can handle abnormal proteins when the person is younger but get overwhelmed as their efficiency falls with age. By preventing this decline in protein clearance, we may be able to keep these people free of symptoms for a longer time.”

Dr. Cuervo will also investigate whether maintaining efficient protein clearance in all the body’s tissues will influence longevity and prevent the functional losses associated with growing old. “There’s reason to hope that drugs exerting a similar effect throughout the body may help us enjoy healthier lives well into old age,” says Dr. Cuervo. Meanwhile, she notes, evidence is mounting that two dietary interventions —low-fat and calorie-restricted diets — help cells to maintain efficient protein clearance.

Source : Albert Einstein College of Medicine

Restoration of chaperone-mediated autophagy in aging liver improves cellular maintenance and hepatic function. Cong Zhang & Ana Maria Cuervo. Nature Medicine. Published online: 10 August 2008; | doi:10.1038/nm.1851

If you’re a fan of habañero salsa or like to order Thai food spiced to five stars, you owe a lot to bugs, both the crawling kind and ones you can see only with a microscope. New research shows they are the ones responsible for the heat in chili peppers.

The spiciness is a defense mechanism that some peppers develop to suppress a microbial fungus that invades through punctures made in the outer skin by insects. The fungus, from a large genus called Fusarium, destroys the plant’s seeds before they can be eaten by birds and widely distributed.

“For these wild chilies the biggest danger to the seed comes before dispersal, when a large number are killed by this fungus,” said Joshua Tewksbury, a University of Washington assistant professor of biology. “Both the fungus and the birds eat chilies, but the fungus never disperses seeds – it just kills them.”

Fruits use sugars and lipids to attract consumers such as birds that will scatter the seeds. But insects and fungi enjoy sugars and lipids too, and in tandem they can be fatal to a pepper’s progeny.

However, the researchers found that the pungency, or heat, in hot chilies acts as a unique defense mechanism. The pungency comes from capsaicinoids, the same chemicals that protect them from fungal attack by dramatically slowing microbial growth.

“Capsaicin doesn’t stop the dispersal of seeds because birds don’t sense the pain and so they continue to eat peppers, but the fungus that kills pepper seeds is quite sensitive to this chemical,” said Tewksbury, lead author of a paper documenting the research.

“Having such a specific defense, one that doesn’t harm reproduction or dispersal, is what makes chemistry so valuable to the plant, and I think it is a great example of the power of natural selection.”

The paper is published the week of Aug. 11 in the online Proceedings of the National Academy of Sciences. Co-authors are Karen Reagan, Noelle Machnicki, Tomás Carlo, and David Haak of the University of Washington; Alejandra Lorena Calderón Peñaloza of Universidad Autonoma Gabriel Rene Moreno in Bolivia; and Douglas Levey of the University of Florida. The work was funded by the National Science Foundation and the National Geographic Society.

The scientists collected chilies from seven different populations of the same pepper species spread across 1,000 square miles in Bolivia. In each population, they randomly selected peppers and counted scars on the outer skin from insect foraging. The damage was caused by hemipteran insects – insects such as seed bugs (similar to aphids and leaf hoppers) that have sucking mouth parts arranged into a beaklike structure that can pierce the skin of a fruit.

The researchers found that not all of the plants produce capsaicinoids, so that in the same population fruit on one plant could be hotter than a jalapeño while fruit from other plants might be as mild as a bell pepper. But there was a much-higher frequency of pungent plants in areas with larger populations of hemipteran insects that attack the chilies and leave them more vulnerable to fungus.

The scientists also found that hot plants got even hotter, with higher levels of capsaicinoids, in areas where fungal attacks were common. But in areas with few insects and less danger of fungal attack, most of the plants lacked heat entirely. In those areas, chilies from the plants that did produce capsaicinoids had a lot less kick because they only produced about half the capsaicinoids as the plants did in areas where fungal attack was common.

Using chemical substances as a defense is not unique to peppers. Tomatoes, for example, are loaded with substances that give their unripened fruit a decidedly unpleasant taste, allowing the seeds a chance to mature and be dispersed. But unlike peppers, tomatoes and most other fruits lose their chemical defenses when the fruit ripens. That is a necessary step, scientists believe, because otherwise the fruit would not be consumed by birds and other animals that disperse the seed. The problem with that strategy, Tewksbury said, is that it leaves the fruit exposed to fungal attack.

“By contrast, peppers increase their chemical defense levels, or their heat, as they ripen. This is a very different model and peppers can get away with it because birds don’t sense pain when they eat capsaicin,” Tewksbury said. “I think a lot of plants would love to come up with this way of stopping fungal growth without inhibiting dispersers. It’s just very hard to do.”

The fact that chilies have capsaicin could be the reason humans started eating the peppers in the first place, he said. Chili peppers and corn are among the earliest domesticated crops in the New World.

“Before there was refrigeration, it was probably adaptive to eat chilies, particularly in the tropics,” Tewksbury said. “Back then, if you lived in a warm and humid climate, eating could be downright dangerous because virtually everything was packed with microbes, many of them harmful. People probably added chilies to their stews because spicy stews were less likely to kill them.”

All chilies originated in South America, and wild chilies now grow from central South America to the southwestern United States. Explorers carried the plants back to Europe, but they were not widely used there. From Europe, chilies made their way to Asia and Africa, where they have become a common ingredient in nearly every tropical cuisine.

“In the north, any adaptive benefit to using eating chilies would be much smaller than at the equator because microbial infection of food is less common and it’s easier to keep food cold. Maybe that’s why food in the north can be so boring,” Tewksbury said.

“Along the equator, without access to refrigeration, you could be dead pretty quickly unless you can find a way to protect yourself against the microbes you ingest every day.”

Source: University of Washington

Scientists from the Gladstone Institute of Cardiovascular Disease (GICD) and UCSF have identified a key regulatory factor that controls development of the human vascular system, the extensive network of arteries, veins, and capillaries that allow blood to reach all tissues and organs. The research, published in the latest issue of Developmental Cell, may offer clues to potential therapeutic targets for a wide variety of diseases, such as heart disease or cancer, that are impacted by or affect the vascular system.

Researchers in laboratory of GICD Director Deepak Srivastava, MD, found that microRNA (miR-126), a tiny RNA molecule, is intimately involved in the response of blood vessels to angiogenic signals. Angiogenesis, the process of vascular development, is a tightly regulated and well-studied process.A cascade of genes orchestrate a series of events leading to formation of blood vessels in an embryo.

“Some of these same gene regulatory networks are re-activated in the adult to direct the growth of new blood vessels” said Jason Fish, PhD, lead author of the study. “This can be beneficial, as in the case of a heart attack.”

Blood vessel formation can also contribute to disease in settings like cancer, where vessels feed a growing tumor.

“Finding that a single factor regulates a large part of the angiogenic process creates a significant target for therapeutic development for any disease involving the vascular system,” said Dr. Srivastava. “The next step is to find ways to modify this microRNA in the setting of disease and test its ability to alter the disease process.”

Researchers examined cells, called endothelial cells, that line the lumen or inside of blood vessels. Once the vascular endothelial cells adopt their fate during development, they come together to form cord-like structures that are remodeled to become lumenized blood vessels. In adults, angiogenic signals, such as vascular endothelial growth factor (VEGF), activate endothelial cells and cause them to form new blood vessels. Individual microRNAs, which titrate the level of specific proteins generated by the cell, were not previously known to affect VEGF signaling or regulate angiogenesis.

The team used three model systems. First, they looked for microRNAs that were enriched in endothelial cells from mouse embryonic stem (ES) cells. They found that miR-126 was the most abundant in and most specific for endothelial cells. They next investigated the function of miR-126 in cultured human endothelial cells and found that this microRNA was involved in the structure, migration, proliferation and survival of endothelial cells. Third, they turned to the zebrafish system to investigate the in vivo function of miR-126 for three reasons. (1) It is a tractable system for perturbing microRNA levels and examining the consequences in a live organism. (2) The developing fish does not require a functioning cardiovascular system to survive through the initial stages of development. (3) The embryos are transparent and can be easily and directly visualized as they are developing. Loss of miR-126 function did not affect the initial patterning of the vascular network, but blood vessels subsequently collapsed and considerable internal bleeding occurred, illustrating the requirement of miR-126 for normal vessel formation and maintenance.

Researchers also found that miR-126 regulated endothelial responses to angiogenic signals by regulating several components of the VEGF pathway, which is important during development of blood vessels and is required for their maintenance. miR-126 repressed the actions of the Sprouty-related protein, SPRED1, and phosphoinositol-3 kinase regulatory subunit 2 both negative regulators of VEGF signals.

They replicated the effects of the loss of miR-126 by increasing expression of Spred1 or inhibiting VEGF signaling. Thus, miR-126 normally promotes vessel formation and stability by “repressing the repressors” of VEGF signaling. Since inhibiting VEGF signaling has been a major target of modern cancer therapies, regulating miR-126 represents an additional approach to regulate blood vessel formation in such diseases.

Source: Gladstone Institutes

Josh: We must remember that many genetic diseases are not caused by mutations in nuclear DNA, but are the result of mutations in mitochondrial DNA. The press release makes mention that the number of cells with mitochondrial mutations often determines the severity of disease; I assume this refers to the ratio of normal:mutant mitochondria within a cell. Remember, the egg had more than a single mitochondrion, and they may or may not all be genetically identical. When more mitochondria are produced in a cell, they may not all replicate at an even rate.

Researchers at the University of Newcastle, England, and the Virginia Bioinformatics Institute at Virginia Tech in the United States have revealed a large reservoir of mitochondrial DNA mutations present in the general population. Clinical analysis of blood samples from almost 3,000 infants born in north Cumbria, England, showed that at least 1 in 200 individuals in the general public harbor mitochondrial DNA mutations that may lead to disease. The findings, which highlight the need to develop new approaches to prevent the transmission of mitochondrial diseases, were published in The American Journal of Human Genetics.

Mitochondria, the “engines” present in each cell that produce adenosine triphosphate, are passed from mother to offspring. Mutations in mitochondrial DNA inherited from the mother may cause mitochondrial diseases that include muscle weakness, diabetes, stroke, heart failure, or epilepsy. In almost all mitochondrial diseases caused by mutant mitochondrial DNA, the patient’s cells will contain a mixture of mutant and normal mitochondrial DNA. The proportion of mutant mitochondrial DNA in most cases determines the severity of disease.

Previous estimates from epidemiological studies suggested that mitochondrial diseases affect as many as one person in 5,000. However, the incidence of new mitochondrial mutations and the prevalence of those carrying these mutations were never fully established due to limitations in the methods used. Most of the earlier estimates of the frequency of mitochondrial DNA mutations in the general population, for example, have depended on identification of clinically affected patients and subsequent retracing of inheritance on the maternal side of the family. This approach fails to detect the gradual accumulation of mutations in some members of the population, including those individuals who harbor mitochondrial DNA mutations but who otherwise do not show the symptoms of disease.

Dr. David Samuels, Assistant Professor at the Virginia Bioinformatics Institute and an author on this study, commented: “We know from many clinical studies of patients and their families that our cells can tolerate a rather large amount of mutant mitochondrial DNA with no significant loss of function. From that observation we have suspected that there may be a large number of people in the general population who carry pathogenic mitochondrial DNA mutations, but who are not obviously ill with a mitochondrial disease. This study gives us, for the first time, a measurement of the number of these carriers of pathogenic mitochondrial DNA mutations in the general population. One in every 200 individuals is a lot of people – around 1.5 million people in the United States alone. ”

The scientists looked at 10 mitochondrial DNA mutations (arising from single nucleotide replacements) often found in patients with mitochondrial disease. By taking advantage of a high-throughput genotyping system that uses mass spectrometry measurements, the researchers were able to detect mutated mitochondrial DNA at high sensitivity. In each positive case, DNA cloning and sequencing were used to confirm the findings. By looking at differences in tissue samples from mother and child, the researchers were also able to estimate the rate at which new DNA mutations had arisen in the population. The incidence of new mutations was close to 100 for every 100, 000 live births.

Dr. Samuels commented: “These new clinical measurements have given direct evidence for the widespread incidence of pathogenic mitochondrial DNA mutations in the human population. These findings emphasize the pressing need to develop effective ways to interrupt the transmission of these mutations to the next generation.”

Source: Virginia Tech

Hannah R. Elliott, David C. Samuels, James A. Eden, Caroline L. Relton, Patrick F. Chinnery (2008) Pathogenic mitochondrial DNA mutations are common in the general population. American Journal of Human Genetics 83(2): 254-260. doi:10.1016/j.ajhg.2008.07.004

My first paper just got published in this month’s issue of the Journal of Clinical Microbiology. We, primarily researchers at Children’s Hospital of Pittsburgh, developed an assay using a technique called Loop Mediated Isothermal Amplification (LAMP) to identify E. coli in a sample, ranging from blood to urine, without the need to first extract the DNA or to use a PCR machine. Rather, a sample can be added directly to a reaction mixture and heated on a heating block for 30-60 minutes. The sample will change color and fluoresce under UV light, allowing a positive result to be quickly and easily identified. We hope that this technique can be used in out patient clinics and clinics in developing countries to identify E. coli infections such as a UTI (urinary tract infection).

Further research is currently being conducted to develop these rapid tests for other infectious agents and bring them into clinical use.

Hill et al. Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Common Strains of Escherichia coli. Journal of Clinical Microbiology. 46 (8): 2800. (2008)

Josh: Normally, I would say it’s probably not the best idea to give gene therapy to cancer patients as a treatment. The reason being that current gene therapy delivery systems have the tendency to cause cancer. However, in this case, which such low survival rates, I think any treatment is worth trying.

Researchers at the Virginia Commonwealth University Massey Cancer Center and the VCU Institute of Molecular Medicine have published findings that implicate a new chemoprevention gene therapy (CGT) for preventing and treating pancreatic cancer, one of the most lethal and treatment-resistant forms of cancer.

In the July issue of Molecular Cancer Therapeutics, the researchers showed that combining a dietary agent with a gene-delivered cytokine effectively eliminates human pancreatic cancer cells in mice displaying sensitivity to these highly aggressive and lethal cancer cells.

Cytokines are a category of proteins that are secreted into the circulation and can affect cancer cells at distant sites in the body, including metatases. The cytokine used in this study was melanoma differentiation associated gene-7/interleukin-24, known as mda-7/IL-24. … Continue Reading »

Josh: More people need to recognize that role that genetics play in their health and what happens to him. Most people really do attribute hearing loss to environmental factors, and there are definitely many cases where this is true, but certainly if a family all begin losing their hearing, especially earlier in their lives, the cause should be recognized as being genetic. I’m glad that at least in this case, someone investigated it.

Pat Phalin learned she had hearing loss at 30, when she volunteered to give hearing tests at her local school. The pupils heard sounds she could not hear.

Her husband Larry, a genealogy enthusiast, saw a pattern in his wife’s family history. Her mother, grandfather and great-grandfather had severe hearing loss as adults. One of the Phalins’ children had hearing problems before he reached school age. … Continue Reading »

Researchers in Germany have discovered that methadone, an agent used to break addiction to opioid drugs, has surprising killing power against leukemia cells, including treatment resistant forms of the cancer.

Their laboratory study, published in the August 1 issue of Cancer Research, a journal of the American Association for Cancer Research, suggests that methadone holds promise as a new therapy for leukemia, especially in patients whose cancer no longer responds to chemotherapy and radiation.

“Methadone kills sensitive leukemia cells and also breaks treatment resistance, but without any toxic effects on non-leukemic blood cells,” said the study’s senior author, Claudia Friesen, Ph.D., of the Institute of Legal Medicine at the University Ulm. “We find this very exciting, because once conventional treatments have failed a patient, which occurs in old and also in young patients, they have no other options.”

Methadone, developed in Germany in the 1930s, is a low cost agent that acts on opioid receptors, and thus is used as an opioid substitute to treat addiction. Scientists have found that opioid receptors also exist on the surface of some cancer cells for reasons that are not understood. One research group tested the agent in human lung cancer cell lines and found that it can induce cell death.

In this study, Friesen and her colleagues tested methadone in leukemia cells in laboratory culture because this cancer also expresses the opioid receptor. Theirs is the first study to look at use of the agent in leukemia, specifically in lymphoblastic leukemia T-cell lines and human myeloid leukemia cell lines.

They found that methadone was as effective as standard chemotherapies and radiation treatments against non-resistant leukemia cells, and that non-leukemic peripheral blood lymphocytes survived after methadone treatment.

To their surprise, they found that methadone also effectively killed leukemia that was resistant to multiple chemotherapies and to radiation. Probing the mechanism of methadone’s action, the researchers found that it activates the mitochondrial pathway within leukemia cells, which activates enzymes called caspases that prompt a cell into apoptosis, also known as programmed cell death. Chemotherapy drugs use the same approach, but methadone activated caspases in sensitive leukemia cells, and also reversed deficient activation of caspases in resistant leukemia cells.

Friesen said the research team is beginning to study methadone treatment in animal models of human leukemia, and she also says that other cancers might be suitable for treatment with the agent.

In this study, the single doses used to kill leukemia cells were greater than doses used to treat opioid addiction, but the researchers have since found that they can use a daily low dose of methadone to achieve the same effect. Friesen adds that while methadone can, itself, become addictive, that addiction is much easier to break compared to addiction to true opioids. “Addiction shouldn’t be an unsolvable problem if methadone is ever used as an anti-cancer therapy,” she said.

Source: American Association for Cancer Research