AIDS viruses reproduce in CD4 cells and circulate in the blood. In this electron micrograph of a white blood cell, AIDS viruses can be seen as the small white dots covering the cell’s surface.
Credit: Centers for Disease Control and Prevention

Today, December 1, 2022, is World AIDS Day. AIDS is the final, life-threatening stages of infection with the human immunodeficiency virus (HIV). HIV damages the immune system, the human body’s most important defense against disease. AIDS stands for acquired immunodeficiency syndrome or acquired immune deficiency syndrome. On this day, we honor over 40 million people who have lost their lives to AIDS and look ahead to ending the AIDS pandemic through research, healthcare, and community support. The World Health Organization reported that 38.4 million people were living with HIV across the globe at the end of 2021.

AIDS is a relatively new life-threatening disease. HIV is spread through sexual intercourse with an infected person or exposure to blood from an infected person, many times through shared needles used to inject drugs. At first, it mainly affected young adults. In the public imagination, the disease soon became associated with risky sexual behavior and with drug abuse. For all these reasons, efforts to address AIDS or to prevent the spread of HIV have at times faced unique social challenges. An infected pregnant woman can transmit HIV to her unborn child before and during the delivery, even if the woman shows no symptoms. An HIV-infected mother may also pass HIV to her baby through breast-feeding.

Since 1986, the international health community has worked to coordinate the global fight against HIV and AIDS. The World Health Organization’s Global AIDS Programme formed the Joint United Nations Programme on HIV/AIDS (UNAIDS) in 1996. Since that time, UNAIDS has worked with other international partners to coordinate the global fight against HIV and AIDS. UNAIDS reported recently that one obstacle to ending AIDS around the world is gender inequality. Many girls and women live with HIV and AIDS without treatment and education to prevent infection. They report that in countries where girls do not receive an education, the rates of HIV infection are higher. UNAIDS also stated that in countries where same-sex relationships are criminalized the probability of infection is increased.

Many individuals and organizations have worked to increase public awareness of AIDS. The most active organizations include community-based groups and the American Red Cross. They hope that greater awareness will generate more compassion and support for people living with AIDS. They also hope to ensure adequate funding for HIV prevention, treatment, and research. One prominent project bringing attention to the crisis is the AIDS Memorial Quilt. Begun by the NAMES Project Foundation in 1987, the quilt consists of thousands of individually designed panels. The panels memorialize people who died of AIDS. The quilt has been displayed throughout the world.

Poor understanding of HIV has at times stoked public fears, leading many people with the virus to suffer unjustly. Some of the infected have lost or been denied jobs or housing. Others have been denied medical care and health insurance. Many children with AIDS were initially barred from attending school or playing on sports teams. To prevent discrimination, people with HIV and AIDS are often included under laws protecting the rights of people with disabilities. The United States government and some states have also strengthened laws safeguarding the confidentiality of medical records relating to HIV infection and AIDS.

Preventing discrimination against people with HIV is not only just—it also protects public health. When people can live without fear of discrimination, they are more likely to seek counseling and treatment. In many cases, such measures lead to earlier diagnosis and a reduction in risky behavior.

AIDS was first identified as a disease by physicians in California and in New York City, New York, in 1981. Doctors recognized the condition as something new because all the patients were previously healthy, young gay men. They sought medical care because they were suffering from otherwise rare forms of cancer and pneumonia. In 1982, the disease was named AIDS. Scientists soon determined that AIDS occurred when the immune system became damaged. They also learned that the agent that caused the damage was spread through sexual contact, shared drug needles, and infected blood transfusions.

AIDS occurs in every nation. In areas such as Africa south of the Sahara, Southeast Asia, and India, HIV transmission has occurred mostly among heterosexual men and women, particularly young adults and teens. Many developing nations carry enormous burdens of HIV infection. For example, the United Nations reports that in some parts of Africa, the infection rate may reach over 30 percent in some urban areas. The huge number of young adults dying of AIDS in Africa south of the Sahara has decreased overall life expectancy across the continent. A growing number of people have also become infected in countries with increasing drug use, such as Russia, China, and the nations of central Europe.

Surgeons performed an eight-hour procedure to transplant a genetically modified pig’s heart into a human on Jan. 7.
Credit: University of Maryland School of Medicine

For the first time ever, surgeons at the University of Maryland Medical Center successfully transplanted a heart from a genetically modified pig to a human. The eight-hour surgery took place on Jan. 7, 2022, in Baltimore, Maryland. The recipient was a 57-year-old man with heart disease, called arrhythmia. He was deemed too sick to receive a human heart. Scientists had altered the genes of the pig to make it more similar to humans, removing four pig genes and adding six human genes through genetic engineering.

More than 107,000 people are on waiting lists to receive organ donations in the United States. Transplanted tissues and organs replace diseased, damaged, or destroyed body parts. They can help restore the health of a person who might otherwise die or be seriously disabled. Commonly transplanted organs include the heart, lungs, kidney, and liver.

Because of the shortage of human organs, researchers are actively investigating the use of donor organs from animals. Transplanting organs from one species to another is called xenotransplantation. Use of pigs as organ donors is an especially active area of research. Pigs are already widely raised for food and leather, and their organs are about the same size as adult human organs. One major concern is preventing accidental transfer of viruses from other animals to people. Another challenge is preventing the recipient’s immune system from destroying a donor organ. If the immune system recognizes that a transplanted organ came from outside the body, the system attacks the organ as a dangerous invader. This reaction is called rejection. Doctors try to prevent rejection by choosing the best donor and prescribing immunosuppressive drugs, which are special medications to protect the transplant.

Xenotransplantation has been studied for over 60 years but is not authorized in the United States. The process of raising genetically modified animals to harvest their organs is widely debated. The Food and Drug Administration gave the surgery team an emergency authorization on Dec. 31, 2021, to conduct the transplant due to the recipient’s condition.

From the long list of people waiting to receive a lifesaving organ, 17 people die each day. This groundbreaking surgery is giving hope to many patients and their family members who are waiting on organs. However, many surgeons and experts believe it is too early to call this xenotransplantation a success.

October 11, 2019

Every year in the first week of October, the Nobel Foundation in Sweden awards Nobel Prizes to artists, economists, scientists, and peace workers who—in keeping with the vision of the Swedish chemist and industrialist Alfred Nobel—have conferred the greatest benefit to humankind. Today, World Book looks at the first three prizes, in the scientific categories of physiology or medicine, physics, and chemistry.

Nobel Prize medal (Credit: Nobel Foundation)

On Monday, October 7, 2019, the Nobel Prize in physiology or medicine was given jointly to the scientists William G. Kaelin, Jr., Sir Peter J. Ratcliffe, and Gregg L. Semenza for their work showing how cells adapt to the changing availability of oxygen. Kaelin, Ratcliffe, and Semenza identified the molecular machinery that allows cells to respond to changes in oxygen levels. Their discoveries offer promising new strategies in the treatment of such diseases and maladies as anemia, cancer, heart attacks, and strokes.

William G. Kaelin, Jr., was born in New York and is a professor of medicine at the Dana-Farber Cancer Institute in Boston and at the Brigham and Women’s Hospital at Harvard Medical School. Peter J. Ratcliffe of the United Kingdom is the director of clinical research at the Francis Crick Institute in London and director of the Target Discovery Institute at the University of Oxford. Gregg L. Semenza, also from New York, is a professor of genetic medicine at Johns Hopkins University in Baltimore, Maryland.

On Tuesday, October 8, the Nobel Foundation announced the prize for physics had been awarded to the Canadian-American cosmologist James Peebles and to the Swiss scientists Michel Mayor and Didier Queloz for their work on explaining the evolution of the universe and for discovering distant exoplanets (planets beyond our solar system). Among other things, Peebles theorized how matter in the young universe swirled into galaxies. In 1995, Mayor and Queloz discovered an exoplanet orbiting a star elsewhere in our home galaxy, the Milky Way, enhancing the study of planetary systems beyond our own that could support life.

James Peebles is the Albert Einstein professor of science at Princeton University in New Jersey. Michel Mayor is an astrophysicist and professor emeritus of astronomy at the University of Geneva. Didier Queloz is a professor of physics at the Cavendish Laboratory at Cambridge University, and at the University of Geneva.

On Wednesday, October 9, the Nobel Foundation announced that John B. Goodenough of the United States, M. Stanley Whittingham of the United Kingdom, and Akira Yoshino of Japan would share the prize for chemistry for developing and refining rechargeable lithium-ion batteries. The lightweight, rechargeable, and powerful batteries are used in everything from mobile phones to laptop computers and electric vehicles. They can also store great amounts of energy from solar and wind power, further enabling the possibility of a fossil fuel-free future.

At 97 years old, John B. Goodenough is the oldest ever recipient of the Nobel Prize. He is currently the Virginia H. Cockrell Chair in Engineering at the University of Texas at Austin. M. Stanley Whittingham is a distinguished professor at Binghamton University, State University of New York. Akira Yoshino is an honorary fellow at Tokyo’s Asahi Kasei Corporation and a professor at Meijo University in Nagoya, Japan.

December 1, 2017

South African surgeon Christiaan Barnard electrified the world 50 years ago on Dec. 3, 1967, by performing the first successful human heart transplant. On that day, Barnard removed the dying heart of Louis Washkansky and replaced it with a healthy one taken from an accident victim. The operation took place at Groote Schuur Hospital in Cape Town, South Africa. Barnard’s surgical skill and daring—combined with his telegenic looks and ready wit—catapulted him overnight into the role of international celebrity. Newspapers and television interviewers scrambled to hear his expert opinion on most everything from health and physical fitness to science to global politics.

The South African surgeon Christiaan Barnard, seen at the center of this photo among his surgical team, performs open heart surgery in Cape Town in 1967. Later that year, Barnard performed the first human heart transplant operation. Credit: © Corbis/Bettmann

Prior to Barnard’s accomplishment, surgeons in Europe and the United States—including pioneering American heart surgeon Norman Shumway—had experimented with several techniques to perform a human heart transplant but had met with little success. In 1967, Barnard was presented with a unique scientific opportunity. Denise Darvall, a 25-year-old office clerk, was unfortunately struck by an automobile in Cape Town. She was rushed to Groote Schuur Hospital, where her brain was found to be clinically dead. However, her still-beating heart was in good condition, and she had the same blood type as Washkansky, an ailing 54-year-old Lithuanian-born grocer. The successful operation took about six hours to complete.

Organ transplant surgery is difficult for even the most skilled surgeons and is prone to complications. The first truly successful human organ transplant operation was done in 1954, when doctors in Boston transplanted a kidney from one person to his identical twin. Because the donor and recipient were genetically identical, there was no danger the transplanted organ would be attacked by the recipient’s immune system. Doctors refer to this complication as organ rejection. The risk of rejection affecting a vital organ such as the heart posed a daunting challenge for surgeons. Washkansky was vulnerable to infection from the large doses of drugs and radiation used to suppress his immune system and prevent organ rejection. He died of pneumonia 18 days after the operation, but his heart functioned normally until his death.

In the United States and Europe, the prospect of heart transplant operations also raised many ethical, moral, and legal considerations. Because the donor’s heart must be transplanted immediately, the problem of determining the exact moment of death was debated by physicians and lawyers. In the United States, death was normally defined as when a person’s heart stopped. Law enforcement officials threatened to arrest surgeons who took organs from brain-dead individuals while the heart remained beating. The delay often led to tissue damage and decreased the chances of a successful transplant operation. Barnard’s success with a brain-dead victim as a heart donor made the practice more acceptable for future organ transplants worldwide.

A month later, on Jan. 2, 1968, Barnard caused a new sensation in racially segregated South Africa by transplanting the heart of a young man of mixed race into a white man. The recipient survived for 19 months and 15 days, in part because Barnard’s team had reduced the amount of antirejection drugs the patient received. Over the years, surgical techniques have been improved and new antirejection drugs have been developed. Today, about 3,000 human heart transplant operations are performed each year in the United States, and about 5,000 are performed annually worldwide.

October 3, 2017

Yesterday, October 2, the Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, awarded the 2017 Nobel Prize in physiology or medicine to American chronobiologists Jeffrey C. Hall, Michael Rosbash, and Michael W. Young. The three scientists were awarded the prize for their discoveries on how circadian rhythms, also known as “biological clocks,” function in organisms, including humans. The science that deals with the study of biological clocks and rhythms is called chronobiology.

Nobel Prize medal (Credit: Nobel Foundation)

Biological clocks control the rhythms of functions and processes in organisms. They keep accurate time during each 24 hours and over days, weeks, months, and even years. Birds migrate, fish spawn, and flowers blossom on schedules that are set by their built-in clocks. In human beings, biological clocks regulate body activities and periods of sleep and wakefulness.

In their Nobel Prize-winning research, the scientists investigated the mechanisms that control the circadian rhythm in the common fruit fly (Drosophila melanogaster). The researchers isolated a particular gene responsible for producing a protein that builds up in the body at night and degrades at a set rate during the day, thus functioning as a biological clock. Hall, Robash, and Young discovered that this same mechanism functions in many other organisms, including people.

The scientists have also worked to raise awareness of the importance of proper sleep in maintaining good health. Their research suggests that a mismatch between the external environment and the internal biological clock may have a negative impact on human health. Such mismatches can occur when people travel across several time zones and experience “jet lag.”

Jeffery C. hall was born on May 3, 1945, in Brooklyn, a borough of New York City. He received his Ph.D. degree from the University of Washington in Seattle in 1971. He is a professor emeritus at Brandeis University in Waltham, Massachusetts, and also affiliated with the University of Maine. Michael Rosbash was born on Mar. 7, 1944, in Kansas City, Missouri. He earned a Ph.D. degree at the Massachusetts Institute of Technology in 1970. He is currently a professor at Brandeis University. Michael W. Young was born on March 28, 1949, in Miami, Florida. He earned a Ph.D. degree at the University of Texas in Austin in 1975. He is currently a professor at Rockefeller University in New York City.

September 28, 2017

An opioid drug crisis has swept parts of the United States in 2017 as unprecedented numbers of people became addicted—and many died. An opioid is any synthetic or semi-synthetic drug that resembles an opiate (drug that contains opium) in its effects. People most often take opioids—which are legally available by prescription—for pain, but the drugs are highly addictive. The opioid crisis has devastated thousands of families and communities.

A pharmacist doles out a prescription of fentanyl, a powerful synthetic opioid that is sometimes combined with heroin. Fentanyl overdoses have killed thousands of people. Credit: Dennis Yip, Fentanyl Safety

Opioid overdose incidents have been widespread and often shocking. For example, a mother collapsed in the stands at a Little League Baseball game in Ohio; an Indiana couple was found unconscious in a running car with two young children in the backseat; and a child called 911 after finding her mother and three adults passed out from overdoses in Massachusetts.

Public health officials have called the current epidemic of opioid overdoses the worst drug crisis in American history. In 2015, the most recent year for which complete data are available, more than 50,000 people died from drug abuse and overdose. Opioids played a role in 33,000 of those deaths. For the first time, deaths from opiate overdose surpassed deaths from homicide with a gun, and overdose deaths were nearly equal to the number of deaths from car crashes. Data from the U.S. Centers for Disease Control and Prevention show the current opioid epidemic has claimed an average of 142 lives each day in 2017.

In the United States, opioid-related visits to hospital emergency rooms have doubled since 2005, and admissions have increased 64 percent. According to a report from the Agency for Healthcare Research and Quality, a unit of the U.S. Department of Health and Human Services, American hospitals experienced an average of 3,500 visits per day for opioid-related issues in 2014, compared with 1,800 per day in 2005. While emergency room visits rose for all age groups, the largest increase was seen in adults age 25 to 44. Men and women were equally likely to seek medical care for opioid-related issues over that time.

Although the epidemic is nationwide, certain areas have been harder hit than others. The Appalachian and nearby regions of Kentucky, Ohio, Pennsylvania, and West Virginia have seen the highest rate of opioid overdose deaths, and parts of New England and the Southwest are also far above the national average.

Opioids are any drugs made from or containing opium and other synthetic drugs that have a similar molecular structure. Opium is a dried milky substance obtained from the opium poppy. Opioids have medicinal value as powerful analgesics (painkillers). Morphine and codeine are familiar medications traditionally made from the opium poppy. Heroin was originally developed by the Bayer pharmaceutical company as a replacement for morphine. Today, opioid drugs are available legally only with a prescription from a doctor, and they are meant to treat severe pain.

Today, most prescription opioid painkillers are partly or totally synthetic. These opioids include hydromorphone (sold under the name Dilaudid); hydrocodone (combined with acetaminophen under the brand name Vicodin); and oxycodone (combined with aspirin under the brand name Percodan). Oxycodone is an opioid drug made from a chemical in the opium poppy called thebaine. A popular slow-release form of the drug is sold under the brand name OxyContin. Like their chemical cousin heroin, synthetic opioids can cause people to become physically dependent or addicted.

For many people, addiction to opioids often begins at the doctor’s office or after a visit to the emergency room. When administered under a doctor’s care, opioids are safe and effective. But should patients continue using these powerful drugs, as they increasingly do for conditions that result in chronic pain, the risk of addiction becomes very real. The same chemistry by which prescription opioids dull severe pain can also lead to crippling addiction and drug abuse—and often overdose and death.

After prescriptions run out or become too expensive, addicted people may resort to buying heroin on the street. Despite being illegal, heroin is widely available and cheaper than prescription pills. Heroin is often mixed with other ingredients or spiked with fentanyl, a synthetic opioid 50 times more potent than heroin.

Fentanyl overdoses have overtaken those caused by heroin in some regions of the United States, and the opioid has been increasingly found among drugs seized by law enforcement officers across the country. Fentanyl and other synthetics with a similar chemical structure, called fentanyl analogues, are so powerful that doses equal to the amount of a few grains of salt can be lethal.

Naloxone is a temporary antidote for opioid overdoses, including those caused by Fentanyl. When properly administered it can restore normal breathing and consciousness to opioid overdose victims. Credit: Dennis Yip, Fentanyl Safety

A drug called naloxone, marketed under the brand name Narcan, is used to treat opioid overdose in emergency situations. The drug blocks or reverses the effects of opioids, which include extreme drowsiness, slowed breathing, and loss of consciousness. Naloxone is administered through an injection. However, emergency medical teams may be unable to revive people who overdose on fentanyl analogues even after multiple injections of naloxone.

As demand for naloxone has increased in response to the opioid epidemic, the price of the drug has followed suit. Many towns and counties burned through their annual budgets for the life-saving drug half way through 2017. Cash-strapped state and local emergency medical response teams are being pushed to the limit because of the crisis. This drain on resources prevents communities from dealing adequately with other medical care needs, further darkening the nation’s health care situation.

Opioid drugs remain an essential treatment for patients with severe pain, and the United States Food and Drug Administration (FDA) requires all manufacturers of such drugs to demonstrate that they are both safe and effective. However, medical experts recognize that more needs to be done to prevent opioid treatment from escalating to addiction.

Medical experts believe that solving the current opioid crisis is more than a matter of law enforcement cutting off the supply of illegally obtained opioid drugs. Treatment for addicts and education programs that emphasize prevention and the seeking of help are also vitally important. Medical experts at the FDA have proposed a policy of “opioid exceptionalism” for prescribing pain medications. Before prescribing opioids to treat pain, doctors would be instructed to consider the risks that a patient might develop an opioid use disorder or become addicted. Doctors would also consider the risk of addicted patients making a transition to other opioids or turning to illicit drugs such as heroin.

In March 2017, President Donald Trump appointed a commission to investigate the opioid crisis. On July 31, the commission recommended that the president declare a national emergency to deal with the epidemic. Public health experts agreed that such bold action is necessary to help Americans understand the severity of the opioid epidemic and to recognize that it is an unparalleled crisis requiring urgent attention.

The opioid commission’s report called for increasing access to naloxone and other medications used to treat overdose or addiction and requiring opioid drug prescribers to receive more education about the proper use of these drugs. The commission also proposed waiving a federal rule that limits addiction treatment for people who receive health care from government-funded Medicaid.

The federal report echoed similar reports from state and local counterparts across the United States. Medical experts emphasized that federal actions to complement state and local efforts help reduce rates of opioid dependence, overdose, and deaths, giving communities the greatest chance of success for ending the current crisis. President Trump, however, dismissed many of the findings detailed in the commission’s report. Instead, he focused on issues unrelated to the opioid crisis, such as stopping the influx of illicit drugs at the border with Mexico. Trump’s insistence on repealing the Affordable Care Act (commonly known as Obamacare) would risk making matters worse by stripping funding for Medicaid—so far the best source of government help for curbing the epidemic.

August 9, 2017

On August 2, a team of scientists from the United States, China, and South Korea announced that they had successfully corrected a harmful disease-causing genetic defect in human embryos. In a groundbreaking experiment, the scientists used a technique called CRISPR-Cas9 (see explanation below) to “edit” a faulty gene in dozens of human embryos. The faulty gene causes a common heart condition that can lead to sudden death later in life. Most of the altered embryos became completely healthy as a result of the procedure. If the embryos were allowed to develop into babies, they would not only be free of the harmful genetic condition, but they would also not pass the disease to any of their descendants. The results of the experiment were published in the online edition of the journal Nature.

This sequence of images shows human embryos that possessed a genetic mutation known to cause a fatal heart condition. They were treated with gene-correcting technology known as CRISPR-Cas9. The embryos then became healthy and divided normally. A baby from such an embryo would be free of the harmful genetic condition. Credit: © Oregon Health & Science University

None of the embryos in the experiment was allowed to grow and develop. However, the scientists conducted the experiment as part of research they hope will ultimately help families that suffer from inherited diseases. Such inherited disorders in humans include cystic fibrosis, hemophilia, muscular dystrophy, sickle cell anemia, and Tay-Sachs disease. Many scientists believe that such diseases can eventually be cured or even eliminated through genetic engineering—the term applied to techniques that alter the genes or combination of genes in an organism, including human beings.

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) refers to a genetic engineering technique that was developed in 2012. It is derived from a process that scientists first observed occurring naturally in bacteria in 1987. The technique uses a protein designated Cas9, which is obtained from bacteria, to break DNA at highly specific locations. Scientists can manipulate this CRISPR-Cas9 process to delete, alter, or replace a gene with great accuracy.

Despite the potential benefits of this technology, experts in scientific ethics are debating whether CRISPR-Cas9 and other advanced gene-editing techniques should be used to alter human embryos. They worry that the techniques could be abused to create genetically modified “designer babies” with made-to-order characteristics. There are also fears that any mistakes in the gene-editing process could inadvertently cause other unknown health problems or even new diseases. These new diseases could then be passed down through families.

Most countries have regulations that limit or prohibit experiments with gene-editing techniques involving humans. The U.S. National Institutes of Health (NIH) prohibit laboratories that receive federal funds from experimenting with human embryos. Such experiments can be done in privately funded laboratories, however, as this experiment was. In addition, the U.S. Food and Drug Administration (FDA) is prohibited from evaluating any treatments that involve genetically modified human embryos. However, government regulations in other countries, including China and the United Kingdom, have recently permitted limited experiments involving human embryos.

October 4, 2016

Yesterday, October 3, officials at the Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, awarded the 2016 Nobel Prize in physiology or medicine to Japanese biologist Yoshinori Ohsumi. Ohsumi earned the award for his discoveries on how cells break down and reuse vital substance.

Nobel Prize medal (Credit: Nobel Foundation)

Ohsumi’s research included studying an organelle called a vacuole in yeast cells. An organelle is a small organlike structure that performs a specialized function within a cell. Within yeast cells, certain specialized vacuoles called lysosomes contain chemicals that break down large food particles for energy and growth. Ohsumi discovered and described how vacuoles also function to break down worn out proteins and nonessential components of cells. The cells can then reuse these substances. In physiology, this process is called autophagy, which comes from the Greek words meaning self-eating.

Yoshinori Ohsumi was born on Feb. 9, 1945, in Fukuoka, on the northwestern part of Kyushu, Japan. He studied cell biology at the University of Tokyo, where he earned his Ph.D. in 1974. After conducting research at Rockefeller University in New York City, he returned to the University of Tokyo and later joined the National Institute for Basic Biology in Okazaki, Japan. Since 2009, Ohsumi has conducted research at the Tokyo Institute of Technology.

October 7, 2013

American scientists James E. Rothman of Yale University and Randy W. Schekman of the University of California at Berkeley shared the 2013 Nobel Prize for physiology or medicine with German-born biologist Thomas Sudhof of Stanford University for  discoveries showing how insulin and other vital materials are transported and delivered to targets within and between cells of the body. This extremely precise transport system is essential for health.

Cells differ greatly in size and shape and in the jobs they do. But all cells have certain features, and each cell can be thought of as a tiny chemical factory. It has a control center that tells it what to do and when. It has power plants for generating the energy it needs to function, and it has machinery for making needed products or performing essential services. Within each cell, a transportation control system ensures that necessary substances are delivered to the right place at the right time and so prevents the cellular factory from breaking down.

Working separately, the three scientists investigated the networks of tiny cavities, called vesicles, that transport materials within and sometimes between individual cells of the body. Rothman studied the various proteins that enable vesicles to deliver such necessary substances as hormones or enzymes to the appropriate target within the cell. Schekman identified the genes that control the cellular transport system. Similar genes are found in all animals, from simple yeast to human beings. Sudhof studied how chemical signals from nerve cells instruct vesicles to release the substances they contain. Such signaling is necessary so that the thousands of complex reactions that take place in the body occur in a precise manner.

The three scientists’ research offers many practical medical applications. Disturbances in the cell’s internal transport system are thought to play a role in diabetes and various neurological and immune system disorders.

Additional World Book article:

• Nobel, Alfred Bernhard

October 8, 2012

Biologists John Gurdon of the Gurdon Institute in the United Kingdom and Shinya Yamanaka of Kyoto University in Japan won the 2012 Nobel Prize in physiology or medicine for their experimental findings on how adult animal cells can be transformed into stem cells. A stem cell is a cell that has the ability to develop into any of the different cell types that make up the tissues and organs of the body. This development process is called differentiation. Stem cells have the ability to divide endlessly, producing more stem cells or other types of cells.

In experiments with frogs conducted in the 1960’s, Gurdon demonstrated that the genetic material from a single cell of an adult frog contained all the information necessary to create a whole frog. He took the genetic material from the intestines of an adult frog and placed it inside an unfertilized frog egg. The resulting cell began to divide and developed into a tadpole as if it were a stem cell. Working independently in Japan, Shinya Yamanaka used a different approach to turn adult cells into stem cells. He altered individual genes in mouse skin cells to transform the cells into stem cells. These stem cells later differentiated into several different kinds of cells.

Being able to transform adult cells into stem cells could eliminate the need for controversial therapies that rely on embryonic stem cells. Scientists first succeeded in isolating (separating) and growing stem cells from a human embryo (developing human) in a laboratory in 1998. Such stem cells are called embryonic stem cells. These cells can differentiate into nerve, liver, muscle, blood, and all other cells that make up an organism.

This discovery led to a debate over whether it is morally acceptable to use cells taken from human embryos for research. The embryos are destroyed in the process of isolating the stem cells. Some people consider embryos as human beings with legal rights and believe it is wrong to destroy them. Other people believe that the potential medical benefits of embryonic stem cells justify their use. Learning how to control the creation and differentiation of stem cells will help scientists develop new treatments for many diseases, including Alzheimer’s disease, diabetes, and heart disease.

Additional World Book articles:

• Bone marrow transplant
• Genetic engineering
• Stem Cells: Seeds of Hope (a Special Report)
• Medicine (2007) (a Back in Time article)