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CLONING WILL BE DONE

 

Dr Lee Silver is a molecular biologist at Princeton University, a renowned fertility scientist, the author of a new book about "cloning and beyond". Genes are his subject and he points out that he has a few that could be improved on. He has asthma, for instance.

Dr Silver believes that we are not that far from being on the brink of a brave new world of reproductive genetics — or reprogenetics as he calls it — where parents will have the choice whether to pass such things on to their children. "If I could have fixed it so my children didn't have asthma, I would have thought very seri­ously about that, it is a basic instinct for parents to want their chil­dren to have all possible advantages. I'm suggesting that our tech­nologies will allow us to get children with, at first, simple traits such as being taller or who are resistant to cancer, or diabetes, or heart disease", he says.

Dr Silver thinks clones have had a bit of a bad press. "Most people get upset about cloning because they think you can replicate an entire person". This is not true, he says, because a cloned child will be growing up in a different time and place than their parent. Not to mention a different personality and soul. All you are doing is creating a later-born identical twin.

Dr Silver doesn't think cloning is so bad. He thinks it is irrele­vant actually. He thinks it is going to become available some place and he thinks it will be used by a small percentage of people. He thinks it is reasonable to happen in 15 years.

He says that cloning is a sideshow. It doesn't do anything to so­ciety. What will have an effect on society is genetics and making genetic changes in the embryo.

He foresees a future where par­ents with enough money will be able to purchase two types of pro­cedures. The first — which he calls The Virtual Child — involves analysing a batch of your own embryos to decide which one has the best genetic profile. This is an extension of genetic screening which is already done for some diseases. The second type of procedure uses genetic engineering to create a Designer Child. The parents choose which genes to add to their embryo and then it is implanted. This is the most significant thing that is going to happen to the human race, ever", says Dr Silver.

Is it immoral to mess around with life in this way? Can the mystery of life be contained in a Petri dish? Is it a sin? Should it be illegal? Dr Silver says that these questions may be very interesting but that they miss an essential point — which is that it will be done.

WHAT IS CANCER?

Actually cancer is not one but many diseases. Under the micro­scope hundreds of different varieties of cancer cells can be identi­fied. Cancer is therefore a group of diseases characterized by ab­normal, uncontrolled, "lawless" growth of body cells. Plants and animals are also subject to cancerous growths.

Cells are the fundamental units of all living matter. In the nor­mal process of growth and repair, cells grow and take their places in the economy of the body according to what may be called the "rules of nature". Cell growth and development is an extremely complicated process whose central secrets have not yet been fath­omed.



Sometimes, for reasons still unknown, a cell or group of cells breaks the ordinary rules of nature. They behave in a disorderly way; they grow wildly. There is no place for them in the normal structure and function of the body. Like weeds in a garden, they crowd out normal, useful cells and steal their food supply. When enough of these wild cells cluster together, they can sometimes be felt as a lump. Unless the growth of these abnormal cancer cells can be checked by some means (usually outside intervention), they oust so many normal cells that the body can no longer function and the victim dies. For example, when cancer cells invade the stomach, they crowd out the specialized stomach cells necessary for digest­ing food. Hence the patient eventually partially starves to death.

Cancer cells can start in any part of the body, but some sites are more favored. Unfortunately these cells rarely remain where they originate. Clusters or clumps of cancer cells break off and travel in the blood stream to other parts of the body — from the breast to the armpits, for example. This spread of cancer cells is called metasta­sis.

Cancer cells are definitely different from ordinary cells, and these differences can be observed in tiny sections of tissue exam­ined under a microscope. Identifying cancer cells is an important part of the job of the pathologist.

Many names have been given to the different cancer cells iden­tified. Most end in the suffix "oma". Thus, for example, carcinoma is cancer of the epithelial tissues (skin, glands, membranes); sar­coma, of connective tissue (bone, muscle); melanoma, of the pig­ment cells of skin. Leukemia, so-called cancer of the blood, reflects a disturbance in the blood-forming organs, which manufacture so many white blood cells that the essential red blood cells are crowded out.

 

 

AIDS – RELATED INFECTIONS

The AIDS-causing human immunodeficiency virus (HIV) does not by itself produce most of the illness and death associated with the acquired immunodeficiency syndrome (AIDS). HIV can dam­age organs directly, but by progressively crippling the body's de­fenses, the virus also sets the stage for the development of oppor­tunistic infections: invasions of microorganisms that proliferate wildly only because the immune system is defective. Such infec­tions, which rarely cause disease— impairment of organ func­tion— in people with a healthy immune system, account for as much as 90 percent of the mortality of AIDS (the end stage of HIV infection).

Antiviral drugs that are effective against HIV, such as zidovudine (AZT), do not eradicate HIV completely, but they do slow the HIV-related decline in immunity. In so doing, they help to delay the onset of opportunistic infections. Until there is a cure for HIV infection, however, the survival time and comfort of patients will depend greatly on therapies that specifically prevent individual opportunistic infections or treat them more effectively.

Research into such therapies has expanded markedly in the past five to 10 years and is already bringing improvements in patient care. For instance, at the start of the AIDS epidemic, there was no way to combat severe infection by cytomegalovirus, a herpesvirus that in immunocompromised patients can cause blindness or dam­age to the digestive tract or lungs. As of 1990, one drug is licensed and a second is widely available for acute therapy and prevention of recurrences. Until recently the disease Pneumocystis carinii pneumonia struck 85 percent of all HIV-infected patients at least once. Today two thirds or more of these episodes can be prevented with medication.

HIV-related opportunistic infections are quite varied, yet they share several features. For example, most of them also arise in peo­ple with immunity impaired for other reasons, such as those who take immunosuppressive drugs to prevent rejection of organ trans­plants.

 

AIR POLLUTION

 

In recent years there has been great interest in the environment and many "new" words have become part of our vocabulary, words such as ecology, environment, photochemical smog and greenhouse effect. Simultaneously we have been made aware of environmental problems caused by the high technology created to achieve the material comforts we demand. Among these problems are the affects of air pollution. Air pollution causes increased respiratory illness in the old and young, decreases visibility, damages plants and animals and has possibly catastrophic effects on global scale.

Air pollution has long been known to have an adverse effect on plants. If we first examine the physiology of the leaf, we can appreciate some of the reasons why damage occurs. The leaf veins function much as the blood vessels do in animals, acting as the transport system for water minerals and food. The leaf tissue is in layers within a skin or epidermis layer on top and bottom and the photosynthesis cells in between. The stomata are entrances in the leaf bottom through which CO enters to take part in the photosynthesis process. These openings are protected by two guard cells which open and close to allow gases to enter or leave the leaf. Such gases can, of course, also include pollutants.

Most of our air pollution comes from combustion of fuels to produce heat and work. The very rapidly accelerating use of such fuels has greatly increased air pollution and the problem of air pollution has become the very urgent problem of our time. Initiatives to clear up one situation may in fact worsen it or create another, that's why the solution of this problem must have come from cooperative efforts between all nations and between all specialists, i.e. biologists, technologists and nontechnologists.

Antarctica: the world park?

 

In the summer, the human population of Antarctica goes up to 2,500. In the winter there are only 700 human beings on the whole continent. It is the last great 'empty ' place on earth, & people in many countries are beginning to think that it must stay that way. They want Antarctica to be the world park: a place where nature will stay free of population & the changes that human beings bring.

The total area of Antarctica is 13,600,000 square kilometers. This is bigger than the United States & Mexico together, & nearly twice the size of Australia. Here you can find the coldest place on earth: the temperature of the Russian Vostok station can go down to - 88 centigrade.

Ninety-eight per cent of the mainland of Antarctica is under ice over one kilometer thick. The Weddle Sea, off Antarctica, contains the world's clearest seawater. It is possible to see to a depth of eighty meters. This is almost as clear as the cleanest water possible.

Two thirds of the world seals live in Antarctica. Antarctica has 188 million birds. Ninety per cent of these are penguins.

People have used huskies for hundred of years to pull sledges in Arctic areas. The first explorers in the Antarctica also used them. But now a new international law has banned them from Antarctica. Many people want to keep Antarctica in its natural state, free of too many humans & animals from outside. Huskies are not natural Antarctic animals of course. But scientists are angry. Dogs are very useful to explorers. Dog clubs around the world want to help the huskies. They will try to find new homes for them. They say they are intelligent & loving animals. But there is a problem. Huskies are natural hunters. If you keep them with other pets, they may eat them.

People did not know about the continent of Antarctica until 1840. No man walked on the mainland until 1895. There is oil under Antarctic waters & coal under the mountains. There are also many kinds of metals. But now there is an agreement between the world's most industrial countries that they will not exploit Antarctica's oil & minerals for at least fifty-five years. They signed the agreement last year in Madrid. Scientists say that if there is mining & drilling for oil in Antarctica it will have very bad effects on the world's weather.

Antarctica is the only continent on the Earth where countries cannot take nuclear weapons.

Visitors to Antarctica say it is extremely beautiful. Înå day you may visit the icy continent as a tourist. Some ordinary people already go there by ships.

 


Date: 2016-01-03; view: 1606


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