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(F) To return to the original question, "How long can humans stay awake?" the ultimate answer remains unclear. Despite the rat studies in Chicago, I am unaware of any reports that sleep deprivation per se has killed any human (excluding accidents and so forth). Indeed, the U.S. Department of Defense has offered research funding for the goal of sustaining a fully awake, fully functional "24/7" soldier, sailor, or airman. Future warriors will face intense, around-the-clock fighting for weeks at a time. Will bioengineering eventually produce genetically-cloned soldiers and citizens with a variant of Morvan’s syndrome who need no sleep but remain effective and happy? I hope not. A good night’s sleep is one of life’s blessings. As Coleridge wrote years ago, "Oh sleep! It is a gentle thing, beloved from pole to pole," and Wilse Webb, a prominent sleep researcher, more recently called sleep the gentle tyrant: It can be delayed but not defeated.

Exercise 6. Are the following statements true or false, according to the text? Explain your answer.

1. A healthy person can survive without sleep no more than three days.

2. Sleep deprivation damages normal functioning of the organism.

3. Prolonged sleep deprivation produces no negative effect on health.

4. Sleep disorders may be a symptom of serious diseases.

5. Sleep disorders can be inherited.

6. Research of sleep has serious implications for economy and industry.

Exercise 7. Would you like to be able to live without sleep? Why? Why not?

Exercise 8. Summarize everything you know about sleep, its functions and sleep disorders into one report.

Unit 8. Coffee

In the cauldron boil and bake;

Eye of newt and toe of frog,

Wool of bat and tongue of dog,

Adder’s fork and blind-worm’s sting,

Lizard’s leg and howlet’s wing. . .

William Shakespeare, Macbeth

Exercise 1. What do you know about coffee?

1. What is coffee produced from?

2. In what regions of the world is coffee grown?

3. What do you know about coffee plants?

4. What is the main active ingredient of coffee?

5. How does caffeine affect the human body?

6. What are the risks of coffee overdose?

7. What other products contain caffeine?

8. How is the effect of coffee different from the effect of tea if caffeine is contained in both?

Exercise 2. Read the following facts about caffeine and coffee trees to check your answers in Exercise 1.

What is caffeine? An alkaloid found in coffee, cocoa beans, tea, kola nuts and guarana. Also added to many fizzy drinks, energy drinks, pep pills and cold and flu remedies. For a single portion of espresso, 50 to 55 roasted coffee beans are required; a single imperfect bean will taint the whole sufficiently to be noticeable. This is because human olfaction and taste senses originated as defense mechanisms that protected our ancestors from rotten—hence, unhealthy—foods.

What does caffeine do? A stimulant of the central nervous system. Pure caffeine is a moderately powerful drug and is sometimes passed off as amphetamine. In small doses, such as the 150 milligrams in a typical cup of filter coffee, it increases alertness and promotes wakefulness. Caffeine also raises heart and respiration rate and promotes urine production. Higher doses induce jitteriness and anxiety. The fatal dose is about 10 grams.

How does caffeine work? Caffeine blocks receptors for the neurotransmitter adenosine, which is generally inhibitory and associated with the onset of sleep. Also raises dopamine levels, and stimulates the release of the fight-or-flight hormone adrenalin (From Newscientist.com).

What is coffee? Raw coffee beans are the seeds of plants belonging to the Rubiaceae family, which comprises at least 66 species of the genus Coffea. The two species that are commercially exploited are Coffea arabica, which accounts for two thirds of world production, and C. canephora, often called robusta coffee, with one third of global output. Robusta coffee plants and all wild coffee species have 22 chromosomes, whereas arabica has 44. Therefore, arabica and other coffee species cannot be crossed to produce a hybrid plant.

Robusta is a high-yielding and disease-resistant tree standing up to 12 meters tall that grows best in warm, humid climates. It produces a cup featuring substantial body, a relatively harsh, earthy aroma, and an elevated caffeine content that ranges from 2.4 to 2.8 percent by weight. Although robusta is sold by many purveyors, it does not give rise to the highest-quality coffee.

Arabica, which originated in the Ethiopian highlands, is a medium- to low-yielding, rather delicate tree from five to six meters tall that requires a temperate climate and considerable growing care. Commercially grown coffee bushes are pruned to a height of 1.5 to 2.0 meters. Coffee made from Arabica beans has an intense, intricate aroma that can be reminiscent of flowers, fruit, honey, chocolate, caramel or toasted bread. Its caffeine content never exceeds 1.5 percent by weight. Because of its superior quality and taste, arabica sells for a higher price than its hardy, rougher cousin.

A good rainfall induces coffee plants to blossom, and some 210 days afterward red or yellow fruit called cherries appear. Each cherry contains two oblong seeds—the coffee beans. The ultimate quality of the resulting coffee beans depends on the genetics of the plant, the soil in which it grows and the microclimate, which encompasses factors such as altitude, the amount of rainfall and sunlight, and daily temperature fluctuations. Along with the roasting processes that are applied, these agricultural and geographical considerations are responsible for the taste differences among the many varieties of coffee beans that suppliers combine to produce the various distinctive blends one can purchase (From Scientific American, June 2002).

Exercise 3. Now read detailed explanation of the effects of caffeine provided by biologist Neal J. Smatresk, Dean of the College of Science at the University of Texas at Arlington, and find answers to these questions:

1. What is a neurotransmitter? What is a second messenger?

2. How does caffeine affect heart?

3. Does caffeine affect all animals?

How does caffeine affect the body?

Caffeine--the drug that gives coffee and cola its kick--has a number of physiological effects. At the cellular level, caffeine blocks the action of a chemical called phosphodiesterase (PDE). Inside cells, PDE normally breaks down the second chemical messenger cyclic adenosine monophosphate (cAMP). Many hormones and neurotransmitters cannot cross the cell membrane, and so they exert their actions indirectly via such second messengers; when they bind to a receptor on the surface of a cell, it initiates a chemical chain reaction called an enzyme cascade that results in the formation of second messenger chemicals.

Historically, cAMP was the first second messenger ever described. Now, however, scientists have identified several major classes of second messengers, which are generally formed in similar ways through a set of molecules called G proteins. The advantage of such a complex system is that an extracellular signal can be greatly amplified in the process, and so have a massive intracellular effect.

Thus, when caffeine stops the breakdown of cAMP, its effects are prolonged, and the response throughout the body is effectively amplified. In the heart, this response prompts norepinephrine--also called noradrenalin--and a related neurotransmitter, epinephrine, to increase the rate and force of the muscle's contractions. Although the two act in concert, norepinephrine is released by sympathetic nerves near the pacemaker tissue of the heart, whereas epinephrine is released primarily by the adrenal glands. These chemical messages lead to "fight or flight" behavior. During stressful or emergency conditions, they raise the rate and force of the heart, thereby increasing the blood pressure and delivering more oxygen to the brain and other tissues.

Caffeine would be expected to have this effect on any animals that used these neurotransmitters to regulate their heartbeat. Generally speaking, the effects of caffeine are most pronounced in birds and mammals. Reptiles have some response, and lower vertebrates and invertebrates have rather small or no responses. From an evolutionary perspective, fish and amphibians don't show as strong a response to epinephrine and norepinephrine as the higher vertebrates, and they lack a well-developed sympathetic (that is, stimulatory) enervation to heart.

Exercise 4. What positive and negative effects produced by coffee do you know? Choose from the list below:

1. Coffee boosts attention, concentration and alertness.

2. Coffee improves mental performance.

3. Coffee increases life expectancy.

4. Coffee helps to fight infections.

5. Coffee prevents aging.

6. Coffee increases the risk of cardiovascular diseases.

7. Coffee can lead to a stroke.

8. Coffee protects against cancer.

Exercise 5. Read the article about health effects of coffee to check your answers in Exercise 4.

Coffee as a Health Drink? Studies Find Some Benefits

By Nickolas Bakalar

Coffee is not usually thought of as health food, but a number of recent studies suggest that it can be a highly beneficial drink. Researchers have found strong evidence that coffee reduces the risk of several serious ailments, including diabetes, heart disease and cirrhosis of the liver. Among them is a systematic review of studies published last year in The Journal of the American Medical Association, which concluded that habitual coffee consumption was consistently associated with a lower risk of Type 2 diabetes. Exactly why is not known, but the authors offered several explanations.

Coffee contains antioxidants that help control the cell damage that can contribute to the development of the disease. It is also a source of chlorogenic acid, which has been shown in animal experiments to reduce glucose concentrations. Caffeine, perhaps coffee’s most famous component, seems to have little to do with it; studies that looked at decaffeinated coffee alone found the same degree of risk reduction.

Larger quantities of coffee seem to be especially helpful in diabetes prevention. In a report that combined statistical data from many studies, researchers found that people who drank four to six cups of coffee a day had a 28 percent reduced risk compared with people who drank two or fewer. Those who drank more than six had a 35 percent risk reduction.

Some studies show that cardiovascular risk also decreases with coffee consumption. Using data on more than 27,000 women ages 55 to 69 in the Iowa Women’s Health Study who were followed for 15 years, Norwegian researchers found that women who drank one to three cups a day reduced their risk of cardiovascular disease by 24 percent compared with those drinking no coffee at all. But as the quantity increased, the benefit decreased. At more than six cups a day, the risk was not significantly reduced. Still, after controlling for age, smoking and alcohol consumption, women who drank one to five cups a day — caffeinated or decaffeinated — reduced their risk of death from all causes during the study by 15 to 19 percent compared with those who drank none.

The findings, which appeared in May in The American Journal of Clinical Nutrition, suggest that antioxidants in coffee may dampen inflammation, reducing the risk of disorders related to it, like cardiovascular disease. Several compounds in coffee may contribute to its antioxidant capacity, including phenols, volatile aroma compounds and oxazoles that are efficiently absorbed. In another analysis, published in July in the same journal, researchers found that a typical serving of coffee contains more antioxidants than typical servings of grape juice, blueberries, raspberries and oranges. “We were surprised to learn that coffee quantitatively is the major contributor of antioxidants in the diet both in Norway and in the U.S.A.,” said Rune Blomhoff, the senior author of both studies and a professor of nutrition at the University of Oslo.

The same anti-inflammatory properties may explain why coffee appears to decrease the risk of alcohol-related cirrhosis and liver cancer. This effect was first observed in 1992. Recent studies, published in June in The Archives of Internal Medicine, confirmed the finding.

Still, some experts believe that coffee drinking, and particularly caffeine consumption, can have negative health consequences. A study published in January in The Journal of the American College of Cardiology, for example, suggests that the amount of caffeine in two cups of coffee significantly decreases blood flow to the heart, particularly during exercise at high altitude.

Rob van Dam, a Harvard scientist and the lead author of The Journal of the American Medical Association review, acknowledged that caffeine could increase blood pressure and slightly increase levels of the amino acid homocysteine, possibly raising the risk for heart disease. “I wouldn’t advise people to increase their consumption of coffee in order to lower their risk of disease,” Dr. van Dam said, “but the evidence is that for most people without specific conditions, coffee is not detrimental to health. If people enjoy drinking it, it’s comforting to know that they don’t have to be afraid of negative health effects.” (NY Times. August 15, 2006)

Exercise 6. In the following text the lines are mixed up. Put them in their proper order. The first and the last lines are in their correct places.

Decaf Coffee Plants Developed

By Sarah Graham

For many coffee lovers, their precious beverage comes with an unwanted ingredient: caffeine. As a result, which solvents flush caffeine from the beans. Their next step is to apply their technique to C. arabica plants, which produce the high-quality Arabica coffee that accounts for 70 percent of the world market. Of course, it remains to percent less caffeine than regular plants do.

Three enzymes are involved in making caffeine in coffee plants. Researchers at the Nara Institute of Science the gene controlling one of these enzymes--theobromine synthase, or CaMXMT1--was repressed. Compared with processes have been developed to remove the compound, although current methods are expensive and

regular plants, leaves from one-year-old GM plants exhibited a 50 to 70 percent reduction in caffeine content.

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