Apoptosis can occur when a cell is damaged beyond repair, infected with a virus, or undergoes stress conditions such as starvation. DNA damage from ionizing radiation or toxic chemicals can also induce 1) ___ via the actions of the tumor-suppressing gene p53, also known as protein 53 (TP53), which regulates the cell cycle and hence functions as a tumor suppressor. If the TP53 gene is damaged, tumor suppression is severely reduced. The “decision” for apoptosis can come from the cell itself, from the surrounding tissue, or from a cell that is part of the 2) ___ system. In these cases apoptosis functions to remove the damaged cell, preventing it from sapping further nutrients from the 3) ___, or to prevent the spread of viral infection. Apoptosis also plays a role in preventing cancer. If a cell is unable to undergo apoptosis, due to mutation or biochemical inhibition, it can continue dividing and develop into a 4) ___. For example, infection by papilloma viruses causes a viral gene to interfere with the cell’s p53 protein, an important member of the apoptotic pathway. This interference in the apoptotic capability of the cell plays a critical role in the development of 5) ___ cancer. Apoptosis is a form of programmed cell death in multicellular organisms. It is one of the main types of programmed cell death (PCD) and involves a series of biochemical events leading to a characteristic cell morphology and death. Processes of disposal of cellular debris whose results do not damage the organism differentiates apoptosis from necrosis, which is a form of traumatic cell death, resulting from acute cellular injury. Apoptosis confers advantages during an organism’s life cycle. For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result is that the digits are separate. Between 50 billion and 70 billion cells die each day due to apoptosis in the average human adult. For an average child between the ages of 8 and 14, approximately 20 billion to 30 billion cells die a day. In a year, this amounts to the proliferation and subsequent destruction of a mass of cells equal to an individual’s body weight. Research on apoptosis has increased substantially since the early 1990s. In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in an extensive variety of diseases. where an insufficient amount results in uncontrolled cell proliferation, such as 6) ___.

ANSWERS: 1) apoptosis; 2) immune; 3) organism; 4) tumor; 5) cervical; 6) cancer

from Heartwire — a professional news service of WebMD

By Sue Hughes, Medscape Alerts – January 22, 2008 (Rockville MD) – The US FDA has updated the labeling for the Ortho Evra contraceptive transdermal patch to include the results of a new epidemiology study that found that users of the patch were at higher risk of developing venous thromboembolism (VTE) than women using oral contraceptive pills.
The label changes are based on a study conducted by the Boston Collaborative Drug Surveillance Program (BCDSP) on behalf of Johnson and Johnson.

“For women who choose to use contraceptives, it is important that they thoroughly discuss with their healthcare providers the risks and benefits involved,” said Dr Janet Woodcock (FDA Center for Drug Evaluation and Research). “This is an example of the FDA working in tandem with the drug manufacturer to keep the public informed of new safety data and epidemiologic studies that might impact health decisions about the use of FDA-approved products,” she added.
In September 2006, the FDA revised the label for Ortho Evra to warn women about the risk of VTE based on two epidemiology studies. One study showed that some women using the patch were at a two-fold greater risk of developing VTE. The other study showed no increased risk compared with women using oral contraceptives containing 30 to 35 μg of estrogen and the progestin norgestimate.

Ortho Evra is a prescription patch containing ethinyl estradiol and norelgestromin. The FDA notes that women using the product will be exposed to about 60% more estrogen than if they were using typical birth control pills, which contain 35 μg of estrogen. Increased levels of estrogen can increase the risk of side effects, including VTE. Women should discuss with their healthcare providers the possible increased risk of VTE with Ortho Evra, which is applied once a week, and balance this risk against the increased chance of pregnancy if women do not take their birth control pill daily, it adds.
The agency says it believes that Ortho Evra is a safe and effective method of contraception when used according to the labeling, which recommends that women with concerns or risk factors for serious blood clots talk with their healthcare provider about Ortho Evra and other contraceptive options.

The complete contents of Heartwire, a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

Sue Hughes is a journalist for Medscape. She joined theheart.org, part of the WebMD Professional Network, in 2000. She was previously science editor of Scrip World Pharmaceutical News. Graduating in pharmacy from Manchester University, UK, she started her career as a hospital pharmacist before moving as a journalist to a UK pharmacy trade publication. She can be reached at Shughes@medscape.net.

Sherwin Nuland was a practicing surgeon for 30 years and treated more than 10,000 patients. Now he is an author and speaker on topics no smaller than life and death, our minds, our morality, aging and the human spirit.

His 1995 book How We Die: Reflections on Life’s Final Chapter, demythologizes the process of dying. Through stories of real patients and his own family, he examines the seven most common causes of death: old age, cancer, AIDS, Alzheimer’s, accidents, heart disease and stroke, and their effects. The book, one of 10 he has written, won the National Book Award and spent 34 weeks on the New York Times best-seller list. His latest book is The Art of Aging: A Doctor’s Prescription for Well-Being.

“He’s delved deeply into his sense of wonder at the human body’s capacity to sustain life and to support our pursuits of order and meaning.”
National Public Radio

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by Miriam Falco, ATLANTA, Georgia (CNN) — Creating a replacement heart for some of the sickest patients may be one step closer, if new research in rats pans out in humans.

Researchers stripped cells from a rat heart and replaced them, getting them to grow into a “bioartificial” heart.

Researchers at the University of Minnesota were able to create a beating heart using the outer structure of one heart and injecting heart cells from another rat.

Their findings are reported in the journal Nature Medicine.

Rather than building a heart from scratch, which has often been mentioned as possible use for stem cells, this procedure takes a heart and breaks it down to the outermost shell. It’s similar to taking a house and gutting it, then rebuilding everything inside. In the human version, the patient’s own cells would be used.

“We took a rat heart and used soap to wash out the cells of the heart,” said Doris Taylor, director of the Center for Cardiovascular Repair, Medtronic Bakken professor of medicine and physiology and lead author of the study.

The process is called “decelluarization.” To do this, Taylor and her team hung up the heart from a dead rat, introduced a regular soap solution into the top of the organ, and let gravity do the work. The soap moved through the heart’s blood vessels, dissolving existing cells, which dropped out of the bottom. This process was repeated until only the outermost casing of the heart was left, resulting in a “white, almost gelatin-looking heart,” Taylor explained. This would be the equivalent of the gutted house.

The rebuilding started with injecting new heart cells, in this case cells from baby lab rats, and pumping them through the heart. By treating the cells as heart cells would be treated and using a pacemaker to help them learn how to pump, they grew into a heart that could pump — essentially rebuilding the organ’s interior.

Taylor says they’ve already started experimenting with pig hearts, which are closer in size to human hearts and because pig hearts are already used for replacement parts for some human heart patients.

The goal is to increase options for human heart patients. The body would be less likely to reject an organ created from its own cells.

The research was partially funded by the University of Minnesota and a research grant from the Medtronic Corp.

According to the American Heart Association, more than 80 million Americans have some form of cardiovascular disease. Heart disease is the No. 1 cause of death in men and women in the United States each year, killing nearly 900,000 people in 2004.

Nearly 5 million Americans suffer from heart failure, usually the result of coronary artery disease caused by blocked arteries or high blood pressure.

Heart transplants are the last resort for end-stage heart disease, but there aren’t enough organs to go around.

In 2006, only 2,192 heart transplants were performed, the American Heart Association said, but 4,000 to 5,000 more people needing a transplant didn’t get one because of a lack of organs.

Growing new hearts for human beings “is still a ways off,” said Dr. Robert Bonow, a past president of the American Heart Association. “It’s interesting and could pay off if they got the cells to grow properly within the heart.” But that still has to be seen. Taylor acknowledges that they have not yet implanted one of these beating hearts into a rat and tried to keep it alive by using the new heart.

Bonow also points out that for many patients, coronary heart disease can be prevented, by not smoking, controlling your diabetes, controlling your blood pressure and reducing the amount of artery blocking bad cholesterol, which are the leading causes of heart attacks, which weaken the heart and can lead a patient to need a new one.

If this research pans out for humans, Taylor said, many hearts that are currently unsuitable for transplant could be used for this procedure.

Currently, a donor heart must be transplanted within the maximum of four hours. Sometimes the suitable patient is more than four hours away. Doctors could use the organs that can’t be transplanted in time to build the scaffolding to grow future hearts. Taylor thinks this could be done. Then, bone marrow cells or blood cells or cells taken from the patient’s heart biopsy — or possibly even stored umbilical cord blood cells — could be injected into a heart scaffold to grow a new heart.

This is still a long way from human application. First these results have to be replicated in the larger pig hearts Those experiments are under way at the University of Minnesota.

If their research continues as planned, Taylor said she could imagine approaching the Food and Drug Administration in three to five years to discuss the possibility of human clinical trials.

Robert Nerem, director of the Institute for Bioengineering and Bioscience at the Georgia Institute of Technology, said the new research is “exciting and has enormous potential, but clearly more needs to be done.”

Neerem doesn’t think this research will lead to creating hearts for transplantation. “I just don’t think that’s where the world of myocardial repair is going,” he said. Instead, he thinks the technology will be used to help create a patch to fix part of the heart. “Most patients, given the choice between transplant and repair, will choose repairs,” Nerem said.

He also said the development has great potential for research purposes: to use such a heart to study what heart disease actually does to the organ, or for the pharmaceutical industry to develop new drugs.

By Stephen Byrnes, ND, RNCP

Oxidative stress (OS) is fast becoming the nutritional and medical buzzword for the 21st century. Implicated in a growing list of diseases, from cataracts to cancer, health-conscious people should take steps to protect themselves against the ravages of free radicals, the active criminals in OS. Despite the growing dangers of OS, there are some simple, but powerful, weapons against it. An avoidance of factors that contribute to OS; a diet of whole, organic, unprocessed foods; and supplemental anti-oxidants, afford the best protection against this serious and insidious condition.

Oxidative Stress (OS) is not, in and of itself, a disease but a condition that can lead to or accelerate it. OS occurs when the available supply of the body’s antioxidants is insufficient to handle and neutralize free radicals of different types. The result is massive cell damage that can result in cellular mutations, tissue breakdown and immune compromise.

What are free radicals? They are highly unstable molecules that interact quickly and aggressively with other molecules in our bodies to create abnormal cells. They are capable of penetrating into the DNA of a cell and damaging its “blueprint” so that the cell will produce mutated cells that can then replicate without normal controls. Free radicals are unstable because they have unpaired electrons in their molecular structure. This causes them to react almost instantly with any substance in their vicinity. Oxygen, or oxyl, free radicals are especially dangerous.

Surprisingly, however, free radicals are involved in many cellular functions and are a normal part of living. When, for example, a mitochondria within a cell burns glucose for fuel, the mitochondria oxidizes the glucose and in so doing generates free radicals. White blood cells also use free radicals to attack and destroy bacteria, viruses and virus-infected cells. The detoxifying actions of the liver also require free radicals.

Although free radicals have useful functions in the body under controlled conditions, they are extremely unstable molecules that can damage cells if left uncontrolled. Free radicals destroy cellular membranes; enzymes and DNA. They accelerate aging and contribute to the development of many diseases, including cancer and heart disease.

Its important to note here that free radicals are also released in the body from the breaking down or detoxification of various chemical compounds. Additionally, certain foods contain free radicals which, when eaten, enter the body and damage it. The major sources of dietary free radicals are chemically-altered fats from commercial vegetable oils, vegetable shortening and all oils heated to very high temperatures.

Antioxidants to the Rescue

Fortunately, the body maintains a sophisticated system of chemical and biochemical defenses to control and neutralize free radicals. Chemical antioxidants scavenge free radicals, that is, they stabilize the unstable free radicals by giving them the electron they need to “calm down.” The antioxidants are usually consumed or used up in this process–they sacrifice themselves.

The main antioxidants are vitamins A, E and C, betacarotene, glutathione, bioflavonoids, selenium, zinc, CoQ10 (ubiquinone), and various phyto-chemicals from herbs and foods. Green tea, for example, is rich in polyphenols–powerful antioxidants that help fight cancer.

Biochemical antioxidants not only scavenge free radicals, but also inhibit their formation inside the body. These include lipoic acid, and repair enzymes such as catalase, superoxide dismutase (SOD), glutathione peroxidase. Melatonin, a hormone produced by the pineal gland, is also a potent antioxidant. Cholesterol, produced by the liver, is another major antioxidant, which the body uses to repair damaged blood vessels. It is probably for this reason that serum cholesterol levels rise as people age. With age comes more free radical activity and in response the body produces more cholesterol to help contain and control the damage.

Of all the antioxidants, glutathione appears to be pivotal. Made up of three amino acids (cysteine, glycine, and glutamic acid), glutathione is part of the antioxidant enzyme glutathione peroxidase and is THE major liver antioxidant. It is a basic tenet of natural medicine that health cannot exist if the liver is toxic. Not surprisingly, extremely low levels of glutathione are found in people suffering from severe OS. People with AIDS, cancer and Parkinson’s disease, for example, typically have very low glutathione levels.

As noted earlier, oxidative stress occurs when the amount of free radicals in the body exceeds its pool of available antioxidants. Obviously, knowing the varied sources of free radicals and avoiding them is an important part of minimizing their harmful effects.

Where Do They Come From?

As noted above, diet can be a major source of free radical stressors with processed or highly heated oils being the main offenders. If you are still using “foods” like refined vegetable oils, margarine or shortening (or “foods” made with them such as all commercial baked goods and “snack” chips), you need to remove them from your diet. Replace these harmful fats with natural, cold pressed oils such as olive oil (which can be used for cooking) and small amounts of flax oil or walnut oil (which should never be heated). Food grade, unrefined coconut oil and organic butter are also excellent choices, especially for cooking. Both of these naturally saturated fats are rich in certain fatty acids that have proven activity against bacteria, harmful yeasts, fungi and tumor cells.

Additionally, since saturated fats (from animal foods and the tropical oils) and monounsaturated oils (from olive oil and cold-pressed nut oils) are more chemically stable, they are much less susceptible to oxidation and rancidity than their polyunsaturated cousins, which are mostly found in vegetable oils. As a general rule, then, although the body does require a small amount of naturally occurring polyunsaturated oils in the diet each day, it’s best not to consume too much of them as they are more prone to free radical attack in the body. As Linus Pauling, PhD noted: “A diet high in unsaturated fatty acids, especially the polyunsaturated ones, can destroy the body’s supply of vitamin E and cause muscular lesions, brain lesions, and degeneration of blood vessels. Care must be taken not to include a large amount of polyunsaurated oil in the diet

The best food sources for polyunsaturates are fish, flax oil, sesame oil, walnut oil and dark green, leafy vegetables. One caveat: canola oil is not recommended due to its chemical instability and its content of trans-fatty acids (TFAs), formed during processing. TFAs are increasingly being linked wtih cancer, immune system dysfunction and heart disease.

Excessive sugar intake can also contribute to free radical damage. White and brown sugars, and even sugar from so-called natural sources, such as fruit and fruit juices, maple syrup and honey, get converted into triglycerides by the liver and are subject to free radical damage. These damaged fats then promptly attack your arteries and directly contribute to cardiovascular disease. Additionally, cancer and tumor cells feed off of sugar. It is for this reason that excessive sugar intake correlates very strongly with heart disease, cancer and a host of other ailments.

Poor nutrition in general contributes to OS. When the body is fed poorly, it slowly starves and all of its systems suffer. Weak organ systems are prime targets for free radical attack.

Free radicals are also released in the body from the detoxification of drugs (whether legal or illegal), artificial food colorings and flavorings, smog, preservatives in processed foods, alcohol, cigarette smoke, chlorinated drinking water, pesticides, radiation, cleaning fluids, heavy metals such as cadmium and lead, and assorted chemicals such as solvent traces found in processed foods and aromatic hydrocarbons such as benzene and naphthalene (found in moth balls).

Even psychological and emotional stress can contribute to OS. When the body is under stress, it produces certain hormones that generate free radicals. Moreover, the liver must eventually detoxify them and that process also generates free radicals.

Heightened OS has also been observed in athletes after intensive workouts due to the physical stress placed on the body. Both physical and emotional stress also prompt the release of endogenous cortisol, an adrenal hormone that reduces inflammation, but also suppresses the immune system.

It should be obvious that all of us are exposed to free radicals from a variety of sources. Those of us living in cities are exposed to very high levels due to increased smog and pollution. Certainly, all of us need to take preventive action. If not, we could face the following conditions in our futures.

Determining OS

When OS occurs, certain by-products are left behind that are excreted by the body, mostly in the urine. These by-products are oxidized DNA bases, lipid peroxides, and malonidialdehyde from damaged lipids and proteins. The higher the levels of these various markers, the greater the chance there is of an OS-induced disease, or the aggravation and acceleration of an existing one. People with Down’s Syndrome, for example, a genetic disorder, are subject to enormous OS due to increased cellular production of hydrogen peroxide, a potent oxidising agent, and frequently develop Alzheimer’s-like conditions in their 30s.

These tests can be ordered by a doctor, naturopath or nutritionist. If you are concerned, ask your health care provider.

Even if you do not have access to formal testing, anyone can do the following simple test to see how much the body has been affected by free radicals: hold out your hand, palm down, in a relaxed position. Pinch the skin on the back of the hand, lift up the fold and then release it. If you have minimal free radical damage, the skin will snap back into place quickly. If the skin takes a few seconds to go back into place, this is not a good sign and action must be taken.

Illnesses Associated With Oxidative Stress

GI Tract: Diabetes, pancreatitis, liver damage, and leaky gut syndrome
Brain and Nervous System: Parkinson’s disease, Alzheimer’s disease, hypertension and multiple sclerosis
Heart & Blood Vessels: Atherosclerosis, coronary thrombosis.
Lungs: Asthma, emphysema, chronic pulmonary disease.
Eyes: Cataracts, retinopathy, macular degeneration.
Joints: Rheumatoid arthritis
Kidneys: Glomerulonephritis
Skin: “Age spots,” vitiligo, wrinkles.
Body in General: Accelerated aging, cancer, autoimmune diseases, inflammatory states, AIDS and lupus.

Food sources of Antioxidants

CoQ10 (ubiquinone): Beef heart, beef liver, sardines, spinach, peanuts
Betacarotene: All orange and yellow fruits and vegetables; dark green vegetables
Zinc: Oysters, herring, lamb, whole grains
Selenium: Butter, meats, seafood, whole grains
Vitamin A: Cod liver oil, butter, liver, all oily fish
Vitamin E: Cold-pressed, unrefined nut and seed oils; wheat germ oil
Vitamin C: Berries, greens, broccoli, kale, kiwi, parsley, guava
Glutathione (GSH): Fresh fruits and vegetables, fresh meats, low-heat dried whey
Bioflavonoids: Most fruits and vegetables, buckwheat
Polyphenols: Green tea, berries.
Herbal Sources: Milk thistle, ginkgo biloba, tumeric, curry (Padma 28, a packaged Ayurvedic herbal formula, is a special blend of herbal antioxidants.)

NOTE: Try to purchase organic foods to minimize pesticide residues.

Oxygen metabolism, although essential for life, imposes a potential threat to cells because of the formation of partially reduced oxygen species.1,2 One electron reduction of oxygen produces superoxide whereas two electron reduction produces hydrogen peroxide. Therefore, electron flow through oxygen, utilizing processes such as the mitochondrial electron transport chain, flavoproteins, cytochrome P450 and oxidases, is tightly coupled to avoid partial reduction of oxygen.3

Normal cellular homeostasis is a delicate balance between the rate and magnitude of oxidant formation and the rate of oxidant elimination. Oxidative stress can, therefore, be defined as the pathogenic outcome of the overproduction of oxidants that overwhelms the cellular antioxidant capacity. Experimental support for oxidative stress as a mediator of cell death was provided recently by the finding that PC12 cells die following downregulation of Cu/Zn superoxide dismutase.4

Antioxidant defenses fall into two categories; enzymatic and nonenzymatic.1-3 Superoxide dismutases are metalloproteins that dismutate the superoxide radical (O2•) to hydrogen peroxide (H2O2) and molecular oxygen. Three types of superoxide dismutases are found in eukaryotic cells; Cu/Zn superoxide dismutase, predominantly located in the cytosolic fractions; Mn superoxide dismutase, located in the mitochondria, and EC superoxide dismutase, which is found in the extracellular space.1 Catalase, a heme protein located predominantly in peroxisomes and the inner mitochondrial membrane, catalyzes the conversion of H2O2 to H2O. In mammalian cells, the conversion of H2O2 to H2O is also accomplished by the reaction with glutathione catalyzed by glutathione peroxidases, a family of cytosolic selenoenzymes. Non-enzymatic defenses include small molecules such as membrane associated a-tocopherol, ascorbate and glutathione.
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Figure 1. Antioxidant Network

Biochemistry of Reactive Species: Free Radicals vs. Oxidants

The term free radicals has been equated with reactive species or oxidants. By definition, a radical is a molecule possessing an unpaired electron. Superoxide, nitric oxide, hydroxyl, alkoxyl and alkyl-peroxyl (lipid) are radicals. However, with the exception of hydroxyl radical none of these radicals are strong oxidants. Thus, not all radicals are strong oxidants and not all oxidants are radicals.

A critical function of reactive species is immunological host response. Generation of reactive species and strong oxidants by inflammatory cells is essential for killing invading microorganisms. However, experimental evidence has implicated reactive species in the pathogenic mechanism of several diseases. It is, therefore, important to understand the biochemical pathways for the induction of oxidative stress by reactive species. The most reasonable biochemical hypothesis is the reactive species-mediated modification of critical cellular targets.

Iron-sulfur enzymes are direct targets for superoxide and toxicity can be derived from the inactivation of these enzymes.1 Hydrogen peroxide at low mM levels does not react with many biological targets at an appreciable rate. However, the reaction of hydrogen peroxide with reduced divalent redox active metals such as iron can lead to the formation of strong oxidants. This reactivity of hydrogen peroxide may be important in biological oxidations of proteins and lipids that take place at the sites of metal binding. Divalent redox active metals can also catalyze the formation of the highly reactive hydroxyl by the metal-catalyzed Haber-Weiss reaction.5,6

O2 + Fe3+
→ O2 + Fe2+

However, hydroxyl radical reacts with almost all biological targets at rates exceeding 109 M-1sec-1 and therefore its diffusion distance inside a cell is minimal. Thus, in order for hydroxyl radical to cause toxicity it must be formed within a few Angstroms from a biological target.

An alternative pathway of superoxide toxicity is the formation of peroxynitrite by the reaction with nitric oxide.7 Nitric oxide is synthesized by nitric oxide synthases and mediates important physiological functions such as vasorelaxation, platelet aggregation, long term potentiation, and immune responses.8-11 The principal biological target of nitric oxide is guanylate cyclase and/or other iron-containing heme proteins. Nitric oxide is a radical but a weak one electron oxidant. Since both •NO and O2• are radicals they react rapidly to form peroxynitrite:

H2O2 +Fe2+
→ • OH + -OH + Fe3+

The second order rate constant of the reaction between nitric oxide and superoxide is 6.7 x 109 M-1sec-1 which is nearly three times faster than the reaction of superoxide with superoxide dismutase (2.9 x 109 M-1sec-1) and nearly thirty times faster than the reaction of •NO with heme proteins. This implies that the formation of peroxynitrite can out-compete the major scavenging pathways for •NO and O2•. Peroxynitrite is not a free radical but a strong one or two electron oxidant and nitrating agent.12-15 Although peroxynitrite can oxidize most biological molecules similar to the hydroxyl radical, the rate constants of the biological oxidations of peroxynitrite are 10,000 fold slower than the rate of hydroxyl radical. This implies that peroxynitrite will diffuse much further than the hydroxyl radical and will react with selective targets. The targets are determined for the most part by the rate by which they react with peroxynitrite. The fastest reactions for peroxynitrite presently are the reactions with Zn-S and Fe-S centers with metalloproteins and carbon dioxide.12,15 Whereas the Zn-S and Fe-S centers will be oxidized, the last two reactivities will promote nitration of tyrosine residues on proteins. Protein nitrotyrosine has been detected in human diseases and experimental models of disease that do not involve an inflammatory process.7

However, hydroxyl radical reacts with almost all biological targets at rates exceeding 109 M-1sec-1 and therefore its diffusion distance inside a cell is minimal. Thus, in order for hydroxyl radical to cause toxicity it must be formed within a few Angstroms from a biological target.

An alternative pathway of superoxide toxicity is the formation of peroxynitrite by the reaction with nitric oxide.7 Nitric oxide is synthesized by nitric oxide synthases and mediates important physiological functions such as vasorelaxation, platelet aggregation, long term potentiation, and immune responses.8-11 The principal biological target of nitric oxide is guanylate cyclase and/or other iron-containing heme proteins. Nitric oxide is a radical but a weak one electron oxidant. Since both •NO and O2 are radicals they react rapidly to form peroxynitrite:

• NO + O2
ONOO

The second order rate constant of the reaction between nitric oxide and superoxide is 6.7 x 109 M-1sec-1 which is nearly three times faster than the reaction of superoxide with superoxide dismutase (2.9 x 109 M-1sec-1) and nearly thirty times faster than the reaction of •NO with heme proteins. This implies that the formation of peroxynitrite can out-compete the major scavenging pathways for •NO and O2•. Peroxynitrite is not a free radical but a strong one or two electron oxidant and nitrating agent.12-15 Although peroxynitrite can oxidize most biological molecules similar to the hydroxyl radical, the rate constants of the biological oxidations of peroxynitrite are 10,000 fold slower than the rate of hydroxyl radical. This implies that peroxynitrite will diffuse much further than the hydroxyl radical and will react with selective targets. The targets are determined for the most part by the rate by which they react with peroxynitrite. The fastest reactions for peroxynitrite presently are the reactions with Zn-S and Fe-S centers with metalloproteins and carbon dioxide.12,15 Whereas the Zn-S and Fe-S centers will be oxidized, the last two reactivities will promote nitration of tyrosine residues on proteins. Protein nitrotyrosine has been detected in human diseases and experimental models of disease that do not involve an inflammatory process.7
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Figure 2. Targets of Reactive Species

Cellular Responses to Reactive Species: Time and Magnitude of Exposure

The flux and the time of exposure are critical factors in determining the outcome of oxidative stress. Aging can be considered the result of a continuous exposure to a low flux of reactive species over the life span. Although the antioxidant networks maintain the critical balance towards physiology, a few reactive species escape the surveillance of the antioxidant network and react with biological targets. Oxidation of biological targets will not necessarily translate to expression of a phenotype because repair processes may sustain normal physiologic function. However, as the frequency of oxidation of biological targets increases (and possibly as repair processes slow), detection of oxidized proteins, lipids and even DNA becomes apparent with aging and other reactive-species mediated pathologies.16-18

Severe oxidative stress results in necrotic cell death. Generation of reactive species during hyperoxia (breathing of >95% oxygen) or reperfusion of an ischemic tissue leads to tissue necrosis.19-20 A moderate exposure to reactive species can also result in cell death that usually occurs 20-24 hours after the initial insult. In most cases delayed cell death resembles apoptosis since DNA fragmentation and other features of apoptosis are evident. It is not clear how reactive species can induce delayed cell death or apoptosis. Potential pathways that once altered by reactive species will lead to delayed cell death include energy sources (mitochondria, activation of Poly- ADP ribosyl synthase), ionic homeostasis, signal transduction and membrane structural integrity.4,21,22

Overall, the inherent ability of cells to withstand oxidative stress is dependent upon several factors: their antioxidant capacity, the ability to sustain metabolic requirements by deriving energy from alternate pathways, efficiency to repair oxidatively modified biomolecules, and availability and utilization of trophic support.

Reactive Species and Signal Transduction

Recently, evidence has suggested that reactive species can be utilized in signal transduction events.23-27 Signal transduction for the most part is viewed either as a specific interaction between proteins or events mediated by second messenger molecules such as Ca2+ and cyclic nucleotides. Nitric oxide can be clearly considered a signal transducing molecule because it specifically activates guanylate cyclase. However, except for nitric oxide, specific targets that can be utilized in signal transduction are not known for other reactive species. Moreover, the steady state levels of reactive species such as superoxide and hydrogen peroxide are under the control of enzymatic pathways. For example, the steady state levels of superoxide in superoxide dismutase deficient E. coli is 5 x 10-7M (taking into account scavenging by glutathione) whereas in superoxide dismutase proficient E. coli the levels are 2 x 10-10 M.28 Therefore, the lack of specificity and the low intracellular levels creates difficulty in explaining how reactive species can be utilized in signal transduction.

The answer to this question in part can be found in the biochemical reactivities and the cellular targets for reactive species. Superoxide, nitric oxide and peroxynitrite react with Fe-S and Zn-S centers. Fe-S and Zn-S centers are not only found in enzymes regulating bioenergetics but also in transcription factors and in iron regulatory proteins. Peroxynitrite is also a nitrating agent that nitrates tyrosine residues in proteins. Nitration alters the pKa of tyrosine residues and interferes with the ability of tyrosine kinases to phosphorylate.29,30 The activity of different kinases, transcription factors and ion channels is redox sensitive and is dependent on a critical cysteine residue which can be modified by reactive species. Finally, reactive species can indirectly induce signal transduction events by inducing mitochondrial Ca2+ release and lipid peroxidation. These signaling pathways may be critical in mediating apoptosis or delayed cell death.

How to Detect and Quantify Reactive Species

The short half life of most reactive species in biological systems does not permit for their direct detection and quantification.3,5,6,23 Therefore, detection of reactive species relies on indirect measurement of modified targets. If you will, consider reactive species as sharks. Their presence in biological systems is therefore determined by the “bite marks” formed on critical cellular targets. In simple in vitro assays, the task of detection and quantification of reactive species is relatively well established. However, as one moves from the simple test tube assay, to cells in culture, to isolated organs, to whole animals or humans, the difficulty in detecting these “bite marks” increases exponentially. The ability to detect and quantify reactive species is a function of the amount of modified molecules present at a given time and the sensitivity of the assay. Biological targets that have been utilized for detection of oxidative modification include lipids, proteins, thiols and DNA. Reactive species react with more than one biological target and since the concentration of biological targets varies among cells, it is difficult to predict which target will be preferentially modified. Therefore, in more complex systems, it may be necessary to measure more than one end-point modification of biological targets. For example, measurement of the reduced to oxidized glutathione ratio will reflect a degree of oxidative stress but will not be useful in elucidating potential pathways responsible for the oxidation. In some models interference with the formation of the potential reactive species maybe useful in elucidating the reactive pathways.

Another method for detecting reactive species is the use of “reporter” compounds that are oxidized by reactive species to either chromogenic, fluorescent, luminescent or Electron Paramagnetic Resonance products. These probes have been utilized in cells, isolated organs and whole animal models and fall in two categories: cell permeable and non-permeable compounds. Intracellular detection requires a substrate that has a reasonably fast rate of reaction with reactive species and can be delivered at high enough concentrations to out-compete antioxidant and scavenging pathways. Extracellular detection represents the fraction of reactive species that are either generated very close to cell membrane or escape the antioxidant and scavenging networks and have not been reacted with cellular targets. This implies that the magnitude of the stress inside the cell could be significantly higher compared to what is measured extracellularly.

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By Gardiner Harris, January 25, 2008, The New York Times — The Food and Drug Administration intends to post inspectors to embassies and consulates throughout the developing world in hopes of improving the quality of the food and medicines increasingly flowing to the United States, a top official said Thursday.

The agency’s commissioner, Dr. Andrew C. von Eschenbach, said that he wanted to have “boots on the ground” in nations like India and China and regions like Central and South America and the Middle East.

The agency already sends inspectors to dozens of countries each year to inspect pharmaceutical plants and clinical trial sites. But Dr. von Eschenbach said in a briefing with reporters that he wanted the agency’s presence abroad to be on an “ongoing and continuous basis rather than episodic and periodic.”

“Right now, we come, we leave,” he said.

The inspectors would primarily “build capacity and bring others in to do inspections that are certified,” Dr. von Eschenbach said.

The agency has long helped to train foreign food and drug inspectors and even advise in the writing of legislation to empower foreign versions of the F.D.A.

As recently as 1996 in Canada and 1999 in Australia, health regulators did not have the authority to inspect clinical trial sites, said Dr. David Lepay, a senior adviser for clinical science at the agency.

“So much of our work has been trying to get authorities who can do something legally in their own countries to develop laws and regulations and put them in place operationally,” he said.

In recent years, as more food and drugs have been produced abroad for sale in America, the F.D.A. has been less able to ensure the products’ safety. The agency inspects less than 1 percent of imported foods.

Some on Capitol Hill have called for a large increase in the agency’s budget to improve such inspections. The Bush administration, however, has not endorsed those calls. Instead, F.D.A. officials have sought to bolster the aggressiveness and effectiveness of foreign health regulators, hoping to prevent unsafe items from being brought to American docks in the first place.

Dr. von Eschenbach said that his plan to post inspectors abroad was still in its infancy. He was not sure whether he would ask for additional financing from Congress for the inspectors or find money in his present budget for them, he said.

He also said that he had yet to work out with the State Department how such inspectors might interact with other parts of the federal government. In addition, host nations would have to request their presence, he said.

In December, the United States and China agreed to a greater American role in certifying and inspecting Chinese food products, including an increased presence of American officials at Chinese production plants.

by Maya Schenwar, January 23, 2008 –  In casting their votes for president this year, Americans rate health care as a top issue – second only to the war in Iraq. Each of the Democratic candidates claims to meet that concern with a plan to provide health insurance for “all Americans.” All of them have referred to their plans as “universal.” But experts are fuzzy on what “universal” means.

“The ‘universal’ is supposed to mean everybody,” said Dr. Robert Blendon, who directs the Program on Public Opinion and Health and Social Policy at Harvard University. “But it has come to include some slippage.” He estimates that the goal of the top candidates’ plans is about 97 percent coverage. None of their plans set a standard for the quality of the insurance that is provided.

The leading candidates’ proposals all include mandates: individuals are required to purchase insurance, employers are required to offer it and those who can’t afford insurance through their workplace will be provided for by government subsidies. The system assumes that all eligible parties will follow the rules and buy insurance – it’s available, not automatic; more affordable, but not free.

All the plans expand eligibility so that fewer people are turned away because of preexisting conditions.

“The three candidates’ plans are very, very similar,” said Don McCanne, senior policy analyst at Physicians for a National Health Care Program. “In Congress, these proposals would be the same bill.”

The main exception is one aspect of Barack Obama’s plan – he only requires insurance for children. Adults would continue under the current standards of the employer-based health care system, though, Obama promises, with much more affordable premiums and access to a greater variety of plans.

In contrast, “long-shot” candidate Dennis Kucinich would provide “single-payer” care: automatic, government-funded coverage, with no out-of-pocket charges.

The Case for Requirements

Why the similarities among the front-runners? Without a single-payer program, mandates are the only way to make close-to-universal care happen, according to Karen Davenport, director of health policy at the Center for American Progress. She likens it to the car insurance requirement: Americans are much more likely to purchase car insurance than they are to, say, invest in a 401K retirement plan, although the benefits of a 401K are clear. (Still, say critics, such a plan would never actually provide for all citizens. Fifteen percent of Californians don’t have auto insurance, despite the state requirement.)

In all three plans, the financial burden of purchasing insurance would be eased by subsidies from employers and the government.

However, none of the candidates has fully addressed the uncomfortable topic of what the penalty would be for those who don’t purchase coverage. Under the Massachusetts health care mandate enacted in 2006, the fine for noncompliance is one-half of an individual’s full insurance premium – a steep price for those who may have opted out because of financial constraints.

“The devil is in the details,” Davenport said. “Clinton and Edwards require insurance for all, but they don’t completely specify how it is going to be enforced.”

Inevitably, even with strict enforcement, individuals will fall through the cracks, according to McCanne. Some simply won’t be able to afford it. Although Medicare will stay in place, and low-income people will receive more subsidies than under the current system, many people with moderate incomes have high outside expenses that suck up the money they “should” be spending on health insurance. With only modest government support, they may not have the cash to pay for premiums.

Others don’t think they need it. Blendon points to young adults, who often assume they’re in good health and may refuse to buy insurance.

In Massachusetts, regardless of the requirement, only seven percent of uninsured individuals who are not eligible for free care have enrolled in insurance plans.

None of the top three candidates would extend insurance to undocumented immigrants.

Under any of them, the mandate system would involve a number of public and private insurance options, making the process – and the role of the government in that process – different for everyone. All three emphasize individual decision-making; Clinton even calls her proposal “the American Health Choices plan.”

However, a mixture of public and private plans, involving differing levels of government subsidies and requirements for employers, adds yet another layer of bureaucracy to the already-convoluted health care system, according to Rudolph Mueller, author of “As Sick As It Gets: The Reality of Healthcare in America.” Mueller commends the candidates for agreeing on a goal of universal coverage, but is wary of mandates – and of keeping the current employer-based arrangement in place.

“They’re making it way too complicated to handle for the average person,” Mueller said. “It leaves all the inefficiencies in the system. It relies on many different funding mechanisms and is not easily accessible.”

A Single Payer Solution?

Clinton, Obama and Edwards have all supplied a rationale for retaining a market-based approach to health care, with Obama – the only one who eschews universal mandates – leading the pack. He claims his plan will fuel competition, providing more options so that insurance companies will be forced to drive their premiums down, making health care affordable enough that everyone will buy it.

“What I see are people who would love to have health care,” he said during a November debate in Nevada. “They desperately want it. But the problem is they can’t afford it.”

However, according to McCanne, neither the mandate method nor the “affordability” method of achieving universal care addresses underinsurance, which presents an increasing dilemma as private insurance companies cut down on the procedures, prescriptions and types of service they cover. Consequently, the best plans are the most expensive, and those who can’t afford those plans end up with inadequate coverage. McCanne maintains this problem won’t disappear until the private health care system does.

The single-payer model has been floated on and off in recent years, most recently as the United States National Health Insurance Act, a bill proposed by Kucinich and Rep. John Conyers Jr. and cosponsored by 87 other Congress members. Its supporters assert that a single-payer system is the only route to 100 percent health care coverage.

“The nature of the private market is to try to compete based on premiums, so companies end up shifting more costs to the beneficiary,” McCanne said. “The Kucinich plan is fully comprehensive. Money no longer becomes a barrier to accessing health care.”

Underinsured individuals frequently behave like the uninsured, avoiding the doctor’s office until their condition is out of control, according to Mueller. They often stop filling their medications and refuse treatment, he said.

John Edwards’s plan includes a hope that his system would “evolve” into a single-payer model, and Obama said earlier this month that he’d opt for single payer if he were designing the system “from scratch.” Yet both dismissed the idea as too impractical and costly to implement immediately.

Mueller argues that a single-payer plan would actually cut costs, since up to 31 percent of current health care funds go toward administrative expenses. A Medicare-for-all plan would bring that number down dramatically, saving up to $200 billion. According to Mueller, that’s much more than enough to insure all currently uninsured individuals.

Moreover, if everyone received free basic maintenance care, fewer people would end up needing expensive treatment, and emergency rooms would not be overloaded with heart attack and stroke victims, according to Mueller.

“As an internist, you see the uninsured coming in really sick, all the time,” Mueller said. “You just shake your head in disgust, because you know you could’ve prevented it.”

The Risk Factor

No matter how many health professionals push for single-payer care, as a presidential candidate, the position is a major political risk, according to Davenport. Polls show that the majority of Americans think the government should guarantee health care for all, but not many trust the government to provide that care itself.

Part of it, according to Davenport, is simply a fear of change.

“People are afraid that with a big change, they’ll lose what little they have,” she said. “There’s a lot of anxiety about that. The leading candidates are really trying to pitch to what will get majority support.”

Along with that fear comes a lack of precedent for full-on government-funded care, according to Blendon. That element of newness, he says, is exacerbated by the current mood of uncertainty and distrust of the federal government’s efforts.
    “We have a system that historically has been based privately,” Blendon said. “In a period of such cynicism, that transition would be hard.”

The front-running candidates, he says, pick up on that sentiment; they aim to reform the current system, not create a new one. Obama and Clinton especially reinforce the sense that market-based health care is the American way, with Obama emphasizing “increasing competition” as a main peg of his plan, and Clinton stating that her proposal “puts consumers in the driver’s seat.”

Letting consumers drive means keeping insurance companies on board to fuel their tanks – and that’s a plus for financing a presidential campaign, McCanne notes. The leading Democratic candidates’ health care plans would provide subsidies for individuals to purchase private health care plans, working to the advantage of the corporations.

Clinton and Obama are the 2008 election cycle’s top recipients of pharmaceutical company money, while both rank close to the top of the list for insurance company money.

The candidates’ health care stances can’t be attributed automatically to campaign financing, according to Blendon: once they pick a position that would benefit the companies, they’ll garner contributions, whether or not they’re motivated by the prospect of those funds.

“If you pick a private sector approach, you’ll get support from the private sector,” he said. “It could be a byproduct of deciding not to go with the big government thing. If you talk about Medicare for all, you won’t get that kind of support. But I don’t know whether it was the chicken or the egg.”

However, for McCanne, the “which-came-first” dilemma is beside the point.

“They’re not going to be belligerent toward an industry that’s helping to elect them,” McCanne said. “It’s a clear-cut conflict of interest. Just the fact of a candidate accepting those funds is not good for the public good.”

Maya Schenwar is a Chicago-based freelance writer and an editor for Publications International.

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