What is Glutamate?

Prolonged excitation is toxic to nerve cells. Neurobiologists recognize that the nerve cell messenger, glutamate, can cause harm when its messages are overwhelming. Normally glutamate is swiftly cleared from the nerve cell junctions to keep the messages brief. Molecules called transporters aid in keeping glutamate in proper concentrations around nerve cells. Abundant evidence points to glutamate as a destructive factor in ALS and investigators are working to find out how this can be changed. Gene therapy approaches are under investigation to deliver glutamate transporters to cells affected by ALS. Other avenues towards control of glutamate in ALS are also under active investigation.

 

What is Glutamate?

Nerve cells pass signals to each other and to their target organs by releasing messenger molecules, called transmitters. Many are simple amino acids such as the one called glutamate.

The message is intended to tell the recipient neuron whether to fire off its own neurotransmitters. As with all neurotransmitters, glutamate docks at specific recognition molecules on the receiving neuron. Glutamate is then swiftly cleared from the nerve cell junctions to keep the message brief. Prolonged excitation is toxic to nerve cells, and neurobiologists recognize that glutamate can cause harm when the messages are overwhelming, as in stroke or epilepsy.

Glutamate’s toxicity is apparently due to calcium flooding the cell. Calcium is supposed to briefly enter the neuron with each signal and triggers the cell to fire off its own signals and adjust its own activities accordingly. But prolonged calcium inside the cell evidently can do damage, and will even activate programmed cell death (see section on apoptosis).

 

Research in the early 1990s determined that ALS patients have raised levels of glutamate in the fluid bathing the brain and spinal cord. In fact, 40 percent of sporadic cases of ALS are characterized by this elevated glutamate in cerebrospinal fluid (CSF). Abundant evidence points to glutamate as a destructive factor in ALS. The first and so far only approved specific treatment for ALS is riluzole, a drug that modulates glutamate.

The transporter that clears glutamate is called EAAT2 (an “excitatory amino acid transporter;” as glutamate is one of the amino acids that serve as transmitters). In ALS, transport of glutamate is slowed into the glial cells that surround the junctions of motor neurons. Indeed, a mutation has been identified in an ALS patient that prevented the transporter from working properly.

Researchers are working towards gene therapy approaches to deliver the glutamate transporter molecule to cells affected by ALS. Other avenues towards control of glutamate in ALS are also under active investigation.

What is homocysteine?

According to Patrick Holford, author of The New Optimum Nutrition Bible, one of the best ways to extending a healthy lifespan is by reducing overall homocysteine levels.

Homocysteine is a type of protein found in the blood which should, ideally, be present in very low quantities. First investigated by Dr. Kilmer McCully in the late 1960s, homocysteine plays a role in many normal body processes such as cell and tissue growth, bone growth, and insulin formation. The proper metabolization of homocysteine relies on the adequate supply of vitamin B6, vitamin B12, and folate. When these vitamins become deficient in the body, homocysteine cannot be converted into substances such as glutathione, the body's most important antioxidant, and a methyl donor called S-adenosylmethionine (or SAMe).

Important for understanding why this conversion from homocysteine to other beneficial substances in the body is the process of methylation. Methylation is how the body maintains its chemical balance through the addition or subtraction of molecules called methyl groups from one substance in order to turn it into another. For example, when stressed, the body responds by adding a methyl group to noradrenaline to produce adrenalin. In reverse, when stress is reduced, the body automatically removes a methyl group from adrenaline, converting it into noradrenaline. This type of chemical reaction occurs billions of times per second and is crucial for the proper functioning of the human body.

 

With this knowledge, when the body cannot convert homocysteine into these two important substances, it builds up in the blood, and these elevated homocysteine levels have now been linked with over fifty diseases including atherosclerosis, certain cancers, diabetes, depression, and Alzheimer's disease. While most Americans have homocysteine levels above 10 units, experts generally believe that a level of 6 units or below is optimal for avoiding the increased risk of diseases associated with high levels.

 

An article written by Dr. Siamak T. Nabili and posted on MedicineNet.com, recommends that healthy adults eat more fresh fruits and vegetable, eat less saturated fat and cholesterol, and take one multivitamin daily. Daily supplementation for the standard' homocysteine level of 10 is as follows: Folic acid (1,200 mcg) / Vitamin B12 (1,000 mcg) / Vitamin B6 (75 mg) / Vitamin B2 (20 mg).

Additional supplementation with zinc (15 mg) and trimethyl glycine, or TMG (1.5-3g), has produced even greater reductions in homocysteine levels. TMG, especially, helps to lower homocysteine levels because it can immediately donate a methyl group to homocysteine, working to immediately detoxify the protein.

Additional recommendations for reducing homocysteine levels include eating a clove of garlic every day, avoiding the addition of salt to foods, cutting back on tea and coffee, limiting alcohol consumption, and quitting smoking.

While Dr. Elson M. Hass believes that routine checks on homocysteine levels and paying close attention to the intake of the vitamins necessary for its conversion, through both diet and supplementation, can help to effectively reduce the risk of having high homocysteine in the blood, it is important to note that there is presently no consensus as to the optimal dose of folic acid and other B vitamins for the treatment of elevated blood homocysteine levels. Additionally, certain risk factors which should be brought to the attention of your healthcare professional, also contribute to varying methods of reducing homocysteine levels.

Among these risk factors are:

- Family history of heart disease, strokes, cancer, Alzheimer's disease, schizophrenic, or diabetes,
- Increasing age,
- Male sex,
- Estrogen deficiency,
- Lack of exercise,
- Hostility and repressed anger,
- Inflammatory bowel diseases,
- Pregnancy, and
- Being a strict vegetarian or vegan.

Ultimately, decisions regarding both testing for high homocysteine levels as well as a lifestyle program to reduce high levels should be individualized after consulting with your doctor. After consultation, testing, and doctor-advised measures are discussed and implemented, a marked reduction in homocysteine levels can usually be achieved within weeks.

References

Hass, E.M., MD, & Levin, B., PhD, RD. (2006). Staying healthy with nutrition: The complete guide to diet and nutritional medicine. Berkeley, California: Celestial Arts.

Holford, P. (1999). The optimum nutrition bible. Berkeley, California: Crossing Press.

Nabili, S., MD, MPH. (2008). Homocysteine. Medicine.net: We Bring Doctors' Knowledge To You. Retrieved March 19, 2009, from http://www.medicinenet.com/hom ocysteine/article.htm.

What is Blood (Part 1)

You know what blood is — it's that red stuff that oozes out if you get a paper cut. The average person has about 1 to 1½ gallons (4-6 liters) of it. But what is blood, really, and where does it come from?

How Does the Body Make Blood?

“Blood is a fluid tissue containing many suspended cells and can be found flowing through the circulatory system transporting substances. These substances may include the digested food substances like amino acids and glucose, excretory products of the body, heat from the respiring body organs and tissues and oxygen and carbon dioxide for respiration. Apart from the transportation of substances, blood also serves to protect the body against pathogens. Pathogens are disease-causing organisms able to inflict disease against the body”

It's not made in a kitchen, but blood has ingredients, just like a recipe. To make blood, your body needs to mix:

1. 
   
   red blood cells, which carry oxygen throughout the body
2. 
   
   white blood cells, which fight infections
3. 
   
   platelets, which are cells that help you stop bleeding if you get a cut
4. 
   
   plasma, a yellowish liquid that carries nutrients, hormones, and proteins throughout the body

Your body doesn't go to the store to buy those ingredients. It makes them. Bone marrow — that goopy stuff inside your bones — makes the red blood cells, the white blood cells, and the platelets. Plasma is mostly water, which is absorbed from the intestines from what you drink and eat, with the liver supplying important proteins.

Put all these ingredients together and you have blood — an essential part of the circulatory system. Thanks to your heart (which pumps blood) and your blood vessels (which carry it), blood travels throughout your body from your head to your toes.

Let's find out more about each ingredient.

1.Red Blood Cells

Red blood cells (also called erythrocytes, say: ih-rith-ruh-sytes) look like flattened basketballs. Most of the cells in the blood are red blood cells. They carry around an important chemical called hemoglobin (say: hee-muh-glow-bin) that gives blood its red color.

Blood and breathing go hand in hand. How? The hemoglobin in blood delivers oxygen, which you get from the air you breathe, to all parts of your body. Without oxygen, your body couldn't keep working and stay alive.

2.White Blood Cells

White blood cells (also called leukocytes, say: loo-kuh-sytes) are bigger than red blood cells. There are usually not a whole lot of white blood cells floating around in your blood when you're healthy. Once you get sick, though, your body makes some more to protect you.

There are a couple types of white blood cells that do different things to keep you well:

Granulocytes

You know how your skin gets a little red and swollen around a cut or scrape? That means the granulocytes are doing their jobs. They have a lot to do with how your body cleans things up and helps wounds heal after an injury. Granulocytes also help prevent infection by surrounding and destroying things that aren't supposed to be in your body and by killing germs.

Lymphocytes

There are two types of lymphocytes, B cells and T cells. B cells help make special proteins called antibodies that recognize stuff that shouldn't be in your body, like bacteria or a virus you get from a sick friend. Antibodies are very specific, and can recognize only a certain type of germ. Once the antibody finds it, it gets rid of the germ so it can't hurt you.

The really cool part is that even after you are better, B cells can become memory cells that remember how to make the special antibody so that if the same germ infects you again, it can kill the germ even faster! T cells also battle germs that invade the body, but instead of making antibodies, they work by making special chemicals that help fight the infection.

Monocytes

Monocytes are white blood cells that fight infection by surrounding and destroying bacteria and viruses.

3.Platelets

Platelets, also called thrombocytes (say: throm-buh-sytes) are tiny round cells that help to make sure you don't bleed too much once you get a cut or scrape. Cuts and scrapes break blood vessels. If a platelet reaches a blood vessel that's been broken open, it sends out a chemical signal that makes other nearby platelets start to stick together inside the vessel.

After the platelets form this plug, they send out more chemical signals that attract clotting factors. These clotting factors work together to make a web of tiny protein threads. The platelets and this web of protein come together to make a blood clot. The clot keeps your blood inside the vessel while the break in the blood vessel heals up. Without platelets, you'd need more than a bandage to catch the blood when you scrape your knee!

4.Plasma

Plasma is a yellowish liquid that is mostly water. But it also carries important nutrients, hormones, and proteins throughout the body. Nutrients are chemicals from the food you eat that give your body energy and other things your body's cells need to do their work and keep you healthy.

Hormones carry messages throughout your body, telling it what to do and when. An example of a hormone is growth hormone. It gets your bones and muscles to grow. Many proteins in plasma are really important to your body, like the clotting factors that help you stop bleeding if you get a cut or a scrape.

Plasma also carries away cell waste — chemicals that the cell doesn't want anymore. Nutrients, hormones, proteins, and waste are dissolved in the plasma — kind of like the cocoa mix that dissolves in a cup of hot water. What are the marshmallows? The blood cells — they float in the plasma.

Blood is thicker than water and has a little bit salty taste. In an adults body there is 10.6 pints of blood circulating around. In their blood there is billions of living blood cells floating in a liquid called plasma. If you took a small sample of this blood and poured it into a test tube and then put it in a machine called a centrifuge, you would be able to see the layers of this blood. This machine spins the blood around so fast that it separates the red blood cells, from the white blood cells, from the platelets. The red blood cells sink to the bottom because they are the heavier, more solid parts, but the plasma remains at the top because it is lighter. The plasma is 95% water and the other 5% is made up of dissolved substances including salts.

Urinary System

Getting Rid of Waste

The urinary system includes the kidneys, bladder and tubes. These organs control the amount of water and salts that are absorbed back into the blood and what is taken out as waste. This system also acts as a filtering mechanism for the blood.

Kidneys

The kidneys are a filter for the blood. The body has two kidneys located in the middle of the back at about the location of your elbows. Blood is pumped from the heart to the kidneys to be cleaned. Each kidney has about 1000 nephrons that act as filters. As the blood goes into a nephron, everything that is dissolved in the blood (waste products, food) is pushed out of the blood into small tubules. As these things travel through the tubule, the water and anything else the body needs goes back into the blood. The rest of the waste products keep moving through the tubule into the urethra. The urethra is the tube that leads to the bladder. The cleaned blood leaves the kidney and travels throughout the body.

Bladder

The bladder is where urine is stored to be released from the body. It can hold between one half to two cups of urine before it needs to be emptied. Everyday about two to five cups of urine pass through the bladder. The more water you drink, the more urine is produced. If it is hot outside and you produce a lot of sweat, you will not make as much urine.

About 96% of urine is water. It also contains some waste salts and a substance called urea. Urea is made during the breakdown of proteins in your liver. Urea may also leave your body in sweat. If urea builds up in your body, it is a sign that your kidneys are not working properly. Kidney failure can be fatal if it is not treated quickly.

Hey, What's Your Blood Type?

Everybody's blood is red, but it's not all the same. There are eight blood types, described using the letters A, B, and O. Those letters stand for certain proteins found on the red blood cells. Not everyone has the same proteins.

In addition to getting a letter or two, a person's blood is either "positive" or "negative." That doesn't mean one person's blood is good and another person's blood is bad. It's a way of keeping track of whether someone's blood has a certain protein called Rh protein. This protein is called "Rh" because scientists found it while studying Rhesus monkeys. If your blood is positive, you have this protein. If it's negative, you don't. Either way is totally fine.

People have one of these eight different blood types:

1. 
   
   A negative
2. 
   
   A positive
3. 
   
   B negative
4. 
   
   B positive 
5. 
   
   O negative
6. 
   
   O positive
7. 
   
   AB negative
8. 
   
   AB positive

Blood types are important if a person ever wants to donate blood or needs a blood transfusion. Getting blood of the wrong type can make a person sick. That's why hospitals and blood banks are very careful with donated blood and make sure the person gets the right type.

People might need blood transfusions when they're sick or if they lose blood. Without enough healthy blood, the body won't get the oxygen and energy it needs. Healthy blood also protects you from germs and other invaders.

Now that you know how important blood is, what can you do? Kids generally aren't allowed to donate blood, but when you're older consider giving the gift of life

Collagen

Whenever you hear the word collagen, the things that would probably come to mind are beauty products. Collagen is well known to women and men who are conscious of their looks, especially when it comes to the issue of aging. Others want to have very plump lips and this is where collagen is used. But do these people really know what collagen is?

Collagen is a type of fibrous protein. It is abundantly found in mammals, which is the main protein in connective tissues and makes about 25% to 35% of the protein content in the whole body. It serves as glue that keeps the body intact.

Collagen possesses a great strength in ductility. It functions differently from any other types of proteins. Its fibers aid in the external structures of the cells and are also present inside the cells.

Collagen works together with the elastic protein called elastin. They support the tissues in the body by giving form and providing strength and firmness. Since elastin gives the tissues in the body the flexibility they need, their combination is important especially in some areas such as the bones, tendons, lungs, and even blood vessels.

Collagen is sometimes related to the skin. It works together with a strong protein called keratin. Keratin is mostly found in skin, hair, teeth, and nails. They provide resilience, strength, and flexibility to the skin. As you grow older, the collagen in the skin degrades and wrinkles occur.

Aside from being an important protein found inside the body, collagen is also associated in medical uses. Nowadays, it is used in cosmetic surgery to enhance some parts or areas of the body. There are also supplements of collagen found in supermarkets intended for joint mobility. Even burns on the skin are being treated and managed with the help of collagen in making skin substitutes.

In the food industry, collagen is also being used in the process of making gelatin. Some cosmetics like make up, lotion, facial cream, scar remover, and stretch marks remover also contain collagen. Collagen has become so popular in cosmetics that it has taken the form of creams, injectables or dermal fillers, and supplements. It has been considered as an important component in anti-aging.

Though collagen is found in many places of the body, the only types of collagen identified and described are so far only 29. Some are the type I, II, III, IV, and V. Type I collagen is mostly found in skin, ligature, vascular, tendon, and bone. Type II is the main component of cartilage. Type III is the main component of the reticular fibers found commonly together with type I. Type IV makes up most of the cell basement membrane. Type V is found on the surfaces of cells, placenta, and hair.

Collagen plays a vital part in the body, hence any deficiency could be very problematic. Genetic diseases are sometimes associated with deficiencies in collagen like the ‘asteogenesis imperfecta’ or also known as the ‘brittle bone disease’. This disease is the result of a very low level of collagen and the presence of low quality collagen.

Leptin

For years, researchers have been studying what makes some people eat more than others: What makes some people eat more calories than they need? What makes us feel full? In 1994 scientists discovered a hormone called leptin. This hormone is produced mostly in the fat cells (a small amount is also produced in the stomach) and sends a signal to the brain that says “We’re full now; we can stop eating”.

What a momentous discovery! The finding of a hormone which signals to the brain we are full . . . Think of the possibilities: If we can isolate this hormone and deliver it to overweight people everywhere, we can suppress their voracious appetites, make them eat less, and eliminate the suffering from the consequences of being overweight forever!

Of course, that idea turned out just as you might suspect–too good to be true. In fact there are extremely rare cases of leptin deficiency leading to obesity that can be “cured” with administering leptin. It seems to be a congenital problem and has been found in perhaps a handful of children.

Giving leptin to people who are overweight seems to do nothing. In fact, obese people already have abnormally high levels of leptin circulating in their blood. Why? It appears they are somewhat resistant to the signals this hormone sends. “Stop eating!” the hormone says, but the brain does not respond.

Is this information the beginning of a journey to a new discovery? A road that will lead to a new drug, perhaps? One that will help suppress the appetite of overweight people and finally give them the feeling of satisfaction; the absence of the drive to eat? Who knows, for now. It could be that there is a biochemical problem making some people resistant to leptin. Their bodies produce more and more of the hormone to signal “stop eating” but somehow it is not well-received.

Could it be a conscious overriding of the signal? For instance, do you stop eating when you are no longer hungry, or do you just keep going to finish what’s on your plate? It’s entirely possible to ignore the body’s signals. We know we can ignore hunger, thirst, or the urge to empty our bladder when we are in the middle of something requiring our concentration. “Just wait” we tell our body; I’m doing something else now but I’ll get to you soon! How often are you receiving signals to stop eating that you ignore?

Next time you eat, stop and feel what your body is telling you. Think about why you continue taking more and more bites of food once you no longer feel hungry. Once your stomach is full, your belt getting tight, your plate nearly empty. Are you overriding the signals to get in a few more bites of something that tastes good? To fit in dessert? To clean your plate?

Let your body work as it is intended to. Listen to the signals. This action could be the real key to your weight loss.

Degenerative Diseases

1. What are degenerative diseases?

Degenerative diseases are non infectious prevalent diseases whose incidences increase with aging.

2. What are risk factors for diseases?

Risk factors for a disease are everything that contributes to increase the risk of the disease to appear. For example, for most cardiovascular diseases, tobacco smoking and diabetes mellitus are both important risk factors; for some cancers having a genetic component a positive family history is a risk factor, etc.

3. What are the main human degenerative diseases?

The main human degenerative diseases are divided into three groups: cardiovascular diseases, neoplastic diseases and degenerative diseases of the nervous system. The main cardiovascular diseases are hypertension, the cardiopathies, including coronary disease and myocardial infarction, and the cerebrovascular accidents (CVAs, or strokes). Neoplasias are benign tumors and cancers. The main degenerative diseases of the nervous system are Alzheimer's disease and Parkinson's disease.

4. What is hypertension?

Hypertension is a disease in which the arterial blood pressure, during systole or during diastole, is abnormally high.

Hypertension, or high blood pressure, is a condition that must be diagnosed and treated since it produces irreversible injuries in arteries and, later, it causes other severe diseases in organs like the heart, brain, kidneys, retina, etc.

5. What are the main risk factors for hypertension?

The main risks factors for hypertension are tobacco smoking, stress, obesity, sedentary lifestyle and alcoholism.

6. What is the relation between the maximum and the minimum blood pressure with the phenomena of systole and diastole?

The maximum blood pressure is the pressure on the wall of the systemic arteries during systole, i.e., when the heart is pumping blood to arterial vessels. The minimum blood pressure is the pressure on the wall of the systemic arteries during diastole, i.e., when the heart ventricles are relaxing and getting blood.

7. What are the main degenerative diseases of the heart?

The main degenerative diseases of the heart are heart failure, arrhythmias, valvular heart diseases, coronary insufficiency and myocardial infarction. 

8. What is coronary disease?

Coronary disease, or coronary insufficiency, is a disease in which there is total or partial obstruction of one or more of the arteries that irrigate the heart musculature, i.e., obstruction of the coronary arteries. The disease is formed by slow and gradual formation of atheroma plaques inside the coronaries. The fatty plaques grow and block the flow of blood, a process known as atherosclerosis (do not confuse with arteriosclerosis which is the hardening of the arteries generally cause by chronic high blood pressure).

The main risk factors for coronary disease are tobacco smoking, diabetes mellitus, hypertension, hypercholesterolemia (high level of bad cholesterol and low level of good cholesterol), stress, alcoholism and sedentary lifestyle.

Coronary disease may present in two manners, as angina pectoris or as myocardial infarction. If the arterial obstruction is not complete and extensive the patient often feels chest pain (angina pectoris), mainly when performing physical exercise or in any situation when the heart needs more oxygen. If the obstruction of one or more coronaries is complete or blood cannot irrigate some regions of the heart muscle (myocardium) the infarction occurs and the muscle cells of the affected area die.

9. What is myocardial infarction?

Myocardial infarction is the condition in which an area of this tissue or the entire heart muscle dies by hypoxia due to lack of blood irrigation. Myocardial infarction is a severe disease since on the dependence of its extension the heart can fail, i.e., it can no longer pump blood to the lungs or to the body or it can even stop beating (causing death).

The main cause of myocardial infarction is coronary obstruction, blocking of the arteries that carry arterial blood to the heart muscle. Other events like hemodynamic shock (circulation stoppage due to large hemorrhages, for example) can also cause myocardial infarction.

10. What is coronary bypass graft?

Coronary artery bypass graft is a kind of surgical myocardial revascularization, i.e., a way to provide blood to a myocardium whose blood supply is impaired or blocked due to coronary disease. In this surgical treatment of coronary disease one or more blood vessel grafts taken from other parts of the body are used to join the obstructed artery (in a region after the obstruction) with the aorta or other healthy coronary artery thus reestablishing the blood flow to the myocardium. Often the blood vessel grafts are part of the saphenous vein from the leg or of the mammary artery from the chest or even of the radial artery from the forearm.

11. What are cerebrovascular accidents?

Cerebrovascular accident (CVA), also known as stroke, is the generic name given to infarction (tissue and cellular death by hypoxia) of areas of the brain due to vascular obstruction or hemorrhages. CVAs are divided into ischemic and hemorrhagic. In the ischemic CVA blocking of arteries that carry blood to the brain occurs; its cause is generally atherosclerosis (atheroma formation) of these vessels. In the hemorrhagic CVA there is rupture of one or more blood vessels of the brain with blood leakage, increasing intracranial pressure and thus interruption of blood flow in some areas of the brain. The severity of the stroke depends on the function performed by the affected area of the brain, for example, motor function, visual function, vegetative function, etc., and on the size of the involved area.

The main risk factors for cerebrovascular accidents are hypertension, hypercholesterolemia, tobacco smoking and old age.

12. What are neoplasias?

Neoplasia is any abnormal and uncontrolled proliferation of cells of an organism. Neoplasias can be benign or malign. Benign neoplasias are those in which the cell proliferation is limited to a given site of the body and so neoplastic cells do not spread to other close regions or at distance through the circulation. Malign neoplasias are those in which the neoplastic cells disseminate at distance to other sites and organs of the body, a process called metastasis, where they continue to proliferate. Malign neoplasias injure tissues and if not eradicated they are fatal. Benign neoplasia can also be deadly when it forms a tumor that grows and compresses vital organs.

13. How different are the concepts of neoplasia, tumor and cancer?

Not every tumor is neoplastic and not every neoplasia creates tumor. Tumor is the generic name given to the abnormal increase in mass or volume of any area of the body (for example, the enlarged tonsils during throat infection are a kind of tumor, any inflammation creating a swelled area characterize a tumor, etc.). Neoplasias can form tumors, some of them very large, by aggregation of neoplastic cells in the region where the neoplasia began or in distant implantations. Cancer is a synonym for malign neoplasia.

14. What is cancer?

Cancers are malign neoplasias, i.e., abnormal and uncontrolled proliferation of cells that can disseminate to other sites of the body. Cancer dissemination at distance usually occurs through blood or lymphatic vessels.

15. How do malign neoplasias appear?

Neoplasias appear due to DNA mutations in genes that regulate the cellular proliferation thus making the cell lose its capacity to control and limit its division by mitosis. The cell then divides continuously and uncontrollably and this defect is transmitted to its daughter cells.

16. What are carcinogens?

Carcinogens are factors capable of producing neoplasias. Any mutagen, a substance that can induce DNA mutation, is a potential carcinogen. Examples of carcinogens are radiation, nitrous acid, many substances inhaled through tobacco smoking and the human papilloma virus (HPV).

17. How do cells of neoplastic tumors obtain oxygen and nutrients and release wastes?

In neoplastic tumors a phenomenon called angiogenesis occurs. Angiogenesis is the formation of new blood vessels. Neoplastic cells induce the formation of new blood vessels to irrigate and drain the neoplastic tissue.

Angiogenesis is important because the tumor growth depends on it. A lot of research on cancer has tried to discover natural and synthetic substances to inhibit angiogenesis.

18. What are the main types of cancer that affect humans?

Excluding skin cancer, that are the more easily detected and so cases are registered in larger number, the main types of cancer in men are prostate cancer, lung cancer, stomach cancer; in women, breast cancer, colon and rectal cancer and lung cancer are of great incidence. Other common cancers are ovarian cancer, pancreatic cancer, liver cancer, esophageal cancer, brain cancer and the leukemias and lymphomas (blood cancers).

Epithelial cancers, of the skin as well as of the internal organs, are more common because epithelial tissues are more exposed to carcinogens.

The proportional incidence of the many types of cancers varies according to the considered population.

19. What is the main risk factor for lung cancer?

The main risk factor for lung cancer is tobacco smoking. The large number of cases of this type of cancer is due to the increased number of smokers worldwide.

20. What is the main risk factor for skin cancer?

The main risk factor for skin cancer is solar exposition of the skin without protection against ultraviolet radiation (a potential carcinogen).

The most lethal skin cancer is melanoma.

21. How is cancer usually treated?

If the cancer is in its initial stage treatment is often done by surgical removal of the neoplastic tissue. Cancers already disseminated are often treated with radiation (radiotherapy) and anti-mitotic drugs (chemotherapy).

22. What are the main degenerative diseases of the nervous system?

The main degenerative diseases of the nervous system are Alzheimer’s disease and Parkinson’s disease.

Degenerative diseases of the nervous system are caused by progressive tissue degradation or loss of neurons in some regions of the nervous system.

23. What is Alzheimer’s disease?

Alzheimer’s disease is a degenerative disease of the central nervous system in which the patient has progressive dementia and alteration of mental functions.

The disease generally appears after 40 years of age and it is more frequent in the elderly. Image studies of the brain show broad loss of brain tissue. (The Alzheimer’s disease should not be confused with other mental deteriorations common in the elderly.)

24. What is Parkinson’s disease?

Parkinson’s disease is a degenerative disease of the nervous system in which the main manifestations are progressive motor disturbances, like tremors of feet, hands and mandibles (jaws) and walking and balance impairments. Parkinson’s disease is due to the degeneration of dopaminergic motor neurons, i.e., motor neurons that use dopamine as a neurotransmitter, located in a specific region of the brain, the mesencephalon. Such degeneration creates deficiency of dopamine in the nervous system. (Parkinson’s disease should not be confused with other causes of tremors, like the use of some medicines.)

Sodium in Food

Sodium occurs naturally in many foods and is also added in the form of salt or other sodium-containing substances. Common salt or table salt is a chemical compound of sodium and chlorine and is called sodium chloride. The sodium content of food has important implications for health. Salt contains about 40 per cent sodium, and a teaspoon of salt, which weighs about 5 grams, contains about 2 grams of sodium.

Rock salt and sea salt are almost entirely sodium chloride, with only traces of other elements (minerals). In contrast to pepper, which loses flavour once ground, there is no advantage in freshly grinding salt prior to its use. Iodized salt contains about 0.03 milligram of iodine per gram of salt. It is intended as a supplement for people whose diet is deficient in iodine. Recent findings in the U.S.A. indicate that the level of iodine in the diet has increased and that the widespread use of this salt is unnecessary.

Varying amounts of sodium are added to food, but not always in the form of salt. Common food additives, such as baking soda, some preservatives, and monosodium glutamate (MSG), also contribute to the total amount of sodium we consume.

SALT AND HIGH BLOOD PRESSURE

Probably one-fifth of the population, because of genetic predisposition, may be increasing their risk of high blood pressure (hypertension) by having a high intake of sodium. People who have a high intake of sodium have a high incidence of hypertension and stroke. High blood pressure is rarely seen in those who consume less than 1.2 grams (1200 milligrams) of sodium per day. In Australia, on the other hand, where the sodium intake can be in the region of 4 to 8 grams per day, about one in five adult Australians has high blood pressure. Salt is not necessarily the only important factor leading to high blood pressure, but in some cases it is. There are sound reasons why Australians should reduce their sodium intake. But sodium is an essential nutrient, and we need a certain amount for normal body function. A safe intake is considered to be between 0.9 and 2.3 grams of sodium per day, although in special circumstances, such as excessive sweating and diarrhoea, higher levels may be needed.

There is usually no need to increase salt intake in hot climates to avoid cramps, fainting and other symptoms because the body's hormones will adjust over a few days and conserve body sodium. Excessive heat presents other risks and should, in any case, be avoided.

HOW CAN WE CONTROL OUR SALT INTAKE?

Some people find it hard to reduce their intake of sodium. We all have the ability to taste salt, but the extent to which we like our food salted can be modified by experience. The amount of salt we consume cannot be wholly controlled by the moderate use of the salt shaker at the dinner table. This use only accounts for about one-third of our daily intake. Up to half of our salt intake is from processed food, with the balance occurring naturally in food and water. The amount consumed in processed food is difficult to control, although with highly salted foods, taste is a reliable guide. Some items that do not taste highly salted can contribute significant quantities of sodium to our diet because of the amounts we consume. Examples include bread, tomato sauce, and cakes and biscuits. Many 'take-away' foods, such as fish and chips, hamburgers and Chinese food, are highly salted. Bottled mineral waters can contribute a significant amount of sodium. An indication of sodium content is usually given on the label.

An increase in potassium intake seems to offset the adverse effect that sodium has on blood pressure. Foods that contain significant amounts of potassium and also low levels of sodium are fresh and frozen fruits and vegetables. But there is no justification for the unrestricted use of potassium salts as substitutes for sodium, as this would present new problems. Potassium supplements and salt substitutes can be potentially hazardous to health and should only be used under medical supervision.

SODIUM INTAKE

Recommended daily dietary intake of sodium (Australia):

Infants:             6-25 millimoles                0.1-0.6 grams

Children:        14-100 millimoles              0.3-2.3 grams

Adults:            40-100 millimoles             0.9-2.3 grams