Quantcast
Channel: Free Online Books » The Environment
Viewing all articles
Browse latest Browse all 5

Health and Disease

0
0

Food and drug CONTAMINATION triggered public health
emergencies. American HIV infection rates were revised
upward, while worldwide MALARIA rates were revised
downward. Experimental advances included a STEM-CELL
TECHNIQUE for improved ORGAN TRANSPLANTATION and a
heart-encircling mesh to treat HEART FAILURE.

 Food and Drug Safety:In 2008 the contamination of infant formula and related dairy products with melamine in China led to widespread health problems in children, including urinary problems and possible renaltube blockages and kidney stones. According to the World Health Organization (WHO), by late 2008 the contamination had led to four infant deaths and the hospitalization of more than 14,000 infants. Melamine, a chemical compound with many industrial uses, had no approved use in food, but according to health officials, it was sometimes added to foods illegally to inflate their apparent protein content as measured with standard tests. Following inspections conducted by China’s national inspection agency, at least 22 dairy manufacturers across the country were found to have melamine in some of their products. The Chinese government responded to the public health crisis by announcing a major shake-up in the dairy industry to improve safety all along the supply chain for dairy products, and it said that it would establish a tracking system to record their flow and delivery. Several countries reported finding melamine in exported Chinese dairy products, including liquid milk and frozen yogurt dessert. All of these products had likely been manufactured with ingredients made from melaminecontaminated milk, according to WHO. Although there had been no reports of illness from contaminated Chinese milk products in the United States, in November the U.S. Food and Drug Administration (FDA) ordered that imported Chinese milk products be held at the border until tests proved that they were not contaminated. Recalls of melamine-tainted products occurred in Australia, Britain, Hong Kong, New Zealand, Singapore, and Thailand. American consumers had become aware of the deadly effects of melamine contamination in 2007 when tainted pet food from China killed more than 4,000 dogs and cats in the U.S. Contaminated lots of the blood-thinning drug heparin were blamed for having caused allergic-type reactions— such as a drop in blood pressure and shortness of breath—in hundreds of persons in the United States from late 2007 through early 2008. The adverse reactions were initially linked to heparin marketed by Baxter, which recalled its heparin products.

the environment  Health and Disease

In the United States, researchers at the CDC reported that the number of Americans newly infected with HIV each year was, and had long been, higher than previously assumed. This conclusion was the result of an improved calculation method that distinguished recent HIV infections from older ones. Using the new formula, the CDC said that about 56,300 new HIV infections occurred in the United States in 2006, 40% more than the previous estimate of 40,000. In addition, the CDC reported that new diagnoses of HIV infection across 33 states increased by 12% annually between 2001 and 2006 among young gay and bisexual men. The report said that the rise was especially significant among young black men aged 13 to 24 who had sex with men. The annual rate of new HIV diagnoses for this group increased by 15% annually, compared with an increase of 9% and 8% annually among their white and Hispanic peers. In another development, scientists found evidence that HIV arose decades earlier than previously believed. According to a study by Michael Worobey, an assistant professor of ecology and evolutionary biology at the University of Arizona in Tucson, and colleagues, HIV began spreading in sub-Saharan Africa between 1884 and 1924, about the time urban centres were established in west-central Africa. Scientists had believed that HIV originated in about 1930. Previous studies had shown that HIV spread to humans from chimpanzees in southeastern Cameroon. Worobey believed that the growth of cities and high-risk behaviours for HIV infection among city dwellers might have been a principal cause of the subsequent spread of the virus. Polio. The Global Polio Eradication Initiative (GPEI) announced in March that Somalia was polio-free once again. Somalia, which had wiped out the disease in 2002, became reinfected in 2005 by poliovirus that originated in Nigeria. The new eradication effort in Somalia had been particularly challenging because of widespread armed conflict, shifting populations, and the lack of a functioning government infrastructure in the war-torn country. The effort involved more than 10,000 Somali volunteers and health workers, who vaccinated more than 1.8 million children under the age of five. Although polio remained endemic in only four countries—Afghanistan, India, Nigeria, and Pakistan—through 2008 the GPEI reported confirmed cases of infection by wild poliovirus in 13 other countries, including 7 countries that had reported no cases in 2007. Health officials reported a resurgence of polio in Nigeria’s northern states, where more than 20% of children remained unimmunized. From 2003 to 2006, poliovirus of Nigerian origin spread to 20 countries, with outbreaks that reached as far as Indonesia. Avian Influenza. In April Egypt confirmed its 50th human case of bird flu—in a two-year-old boy. Bangladesh confirmed its first human case in May, and two new cases of human infection were reported in Indonesia in December. Out of a total of 139 human cases in Indonesia since 2004—the highest total reported by any country—113 had been fatal. A study published in The New England Journal of Medicine said that scientists had developed a whole-virus bird-flu vaccine, Celvapan. It appeared to be safe and more effective than bird-flu vaccine that was currently approved for human use. The study was conducted by Baxter, Celvapan’s manufacturer, and found that 75% of volunteers produced antibodies against the virus after having received a second dose of the vaccine, compared with only 45% in the currently approved vaccine. The study’s author said that Celvapan provided protection from several bird-flu virus strains, that it could be produced in less than one-half the time of traditional methods, and that it did not require an additive to boost an immune response. Baxter was seeking approval of the vaccine for use in Europe and the United States. Other Infectious Diseases. A report published in February found that the rate of incidence of multidrug-resistant tuberculosis (MDR-TB) was at its highest ever and that extensively drug-resistant tuberculosis, which was considered virtually untreatable, had been recorded in 45 countries.

the environment  Health and Disease

Each consortium member planned to conduct a comprehensive high-resolution analysis of the full range of genomic changes in at least one specific type or subtype of cancer, and each analysis was expected to involve specimens from at least 500 patients and to cost an estimated $20 million. A study presented in September at the American Society of Clinical Oncology’s 2008 Breast Cancer Symposium in Washington, D.C., highlighted progress in making diagnoses. An experimental screening technique known as molecular breast imaging, which used an injected radioactive tracer, detected three times as many breast cancers as conventional scanning techniques in women who had dense breasts and who were at a higher risk of developing the disease. In a study published in August in The New England Journal of Medicine, Jane J. Kim and Sue J. Goldie of Harvard University analyzed the cost-effectiveness of vaccination programs for immunizing women against viruses that caused cervical cancer and evaluated the implications of their findings for vaccination guidelines. As the result of the success of clinic trials and subsequent national vaccination programs, within just a few years tens of millions of girls and women had received doses of Gardasil or Cervarix, vaccines that targeted two strains of the human papillomavirus that together caused an estimated 70% of cervical cancers. The authors concluded that the vaccines would be costeffective if they proved to protect women for a lifetime and if current methods for screening for cervical cancer by means of Pap smears could be safely adjusted to reduce costs. In an accompanying editorial, Charlotte J. Haug, editor of The Journal of the Norwegian Medical Association, observed that many uncertainties remained concerning the vaccines, such as how long the immunity would last or whether eliminating some strains of cancer-causing virus might decrease the body’s natural immunity to other strains. She urged that clinical trials and follow-up studies be continued to test unproven assumptions about the two vaccines. A study published in October in the Journal of Clinical Oncology found that persons with pancreatic cancer were more likely than those without the disease to have been previously infected with the hepatitis B virus. Lead author James L. Abbruzzese from the M.D. Anderson Cancer Center in Houston noted that although the study had shown an association between hepatitis B and pancreatic cancer, it did not prove a cause and effect. (Hepatitis B was known to cause liver cancer in some patients.) Though uncommon, pancreatic cancer was among the deadliest forms of cancer, and a vaccine existed to prevent hepatitis B.

Cardiovascular Disease:The American Academy of Pediatrics in July recommended that some children as young as eight years of age take cholesterol-fighting drugs to ward off potential future heart problems. The academy also recommended low-fat milk for one-yearolds, as well as more cholesterol testing. Stephen Daniels, of the academy’s nutrition committee, said that the advice was based on mounting evidence that the cardiovascular damage that leads to heart disease begins early in life. He added that the recommendation for the cholesterol-fighting drugs stemmed from recent research that showed that they were generally safe for children. In general, the drug treatment would be targeted for children at least eight years old who had too much LDL, or “bad,” cholesterol as well as risky conditions such as obesity and high blood pressure. The new recommendation prompted debate among pediatricians, with critics saying that there was no evidence that giving statins to children would prevent heart attacks later in life and that there were no data on the potential side effects of taking the drugs for decades. More than 100 heart patients took part in clinical trials to test the effectiveness of the HeartNet Ventricular Support System to stop advanced heart failure. The system used an elastic metallicalloy mesh that was wrapped around the heart through a minimally invasive implant procedure. According to Heart- Net’s developer, Paracor Medical, the mesh exerted a mild pressure on the heart and was designed to slow or stop the enlargement of the heart that was associated with heart failure. The Heart- Net device was first implanted in 2006.

Alzheimer Disease:Research to develop drugs that could cure or halt the progression of Alzheimer disease experienced setbacks during 2008. To date there were only medications to treat the symptoms of the disease, such as memory loss and confusion. During the year, Myriad Genetics announced that Flurizan, a drug that it had developed to treat Alzheimer disease, failed in a late-stage clinical trial. Flurizan was one of the first drugs to reach late-stage testing that worked by trying to prevent the buildup in the brain of toxic amyloid plaques, which had been thought to cause the disease. Moreover, a study published in July in The Lancet said that a once-promising experimental vaccine called AN1792 failed to prevent the progression of Alzheimer disease, even though it cleared amyloid plaques in the brain. On the positive side, another study published in The Lancet in July reported that an older drug called dimebon significantly helped Alzheimer symptoms. Rachelle S. Doody, at Baylor College of Medicine in Houston, and colleagues studied the effects of dimebon on 183 patients in Russia with mild to moderate Alzheimer disease. The drug was not being marketed and had been previously used in Russia as an antihistamine. Doody’s team found that patients on dimebon had a significant increase in cognitive ability, compared with those who received a placebo. Treated patients also showed improvement in thinking abilities, behavioral symptoms, and daily skills. At the International Conference on Alzheimer disease in August, John Ronald, of the University of Western Ontario, and his colleagues reported that they had identified the brain plaques associated with the disease by using magnetic resonance imaging.

the environment  Health and Disease

Pharmaceuticals:Prostate-cancer specialists reported that the drug finasteride could reduce men’s risk of developing the disease by 30%. Finasteride already was used by millions of men to shrink the prostate. As many as 100,000 cases of prostate cancer could be prevented annually by taking the drug, according to Eric Klein of the Cleveland Clinic. The discovery arose from an analysis of a large American study of finasteride. Nevertheless, it was debated whether men should take the drug to prevent prostate cancer, which in a given individual might or might not be dangerous because the cancer was relatively slow-growing and often not lethal. On the one hand, doctors said many men diagnosed with prostate cancer chose to be treated, which could potentially leave them impotent or incontinent. On the other hand, men who considered taking finasteride would need to weigh the risk of unanticipated side effects that might emerge years later from taking the drug even if they avoided developing prostate problems.

Other Developments:For the first time, doctors performed a human trachea (windpipe) transplant by using tissue that was grown from the recipient’s own stem cells—a procedure intended to prevent the immune system from rejecting the new organ. Doctors from four European universities performed the surgery in Barcelona on a 30-year-old woman who suffered from a severely collapsed lung owing to tuberculosis. In preparation for the transplant, a donor’s trachea was first stripped of cells that would have been rejected when transplanted. Stem cells from the woman’s bone marrow were then used to create cartilage and tissue cells to cover and line the trachea. Details of the procedure were published in The Lancet, which reported that the woman did not require immune-suppressing drugs and was doing well months after the surgery. Although the surgery was considered an important advance in stem-cell technology, scientists said that the ability to grow entire organs with stem cells remained only a far-off possibility. A newly passed U.S. law required insurance companies to provide equal coverage for mental and physical illnesses. As a result, more than one-third of all Americans were expected to receive better coverage for mental health treatments. Many insurers set higher co-payments and deductibles and stricter limits on treatment for addiction and mental illnesses. The new law would make it easier for people to obtain treatment for a wide range of conditions, including depression, autism, schizophrenia, eating disorders, and alcohol and drug abuse. Federal officials said that the law would improve coverage for 113 million persons, including 82 million in employer-sponsored health plans that were not subject to state regulation. The effective date for most of the plans would be Jan. 1, 2010. Taiwanese researchers reported in June that the already high worldwide rate of chronic kidney disease (CKD) was increasing and that because it raised the risk of death, addressing the disease should be a public health priority. The study, which analyzed data from 462,293 persons, found that the 12% of people with CKD were 83% more likely to die from any cause and twice as likely to die from cardiovascular causes, compared with those without CKD. About 40% of deaths in the CKD group occurred before age 65. Of the deaths in the entire study group, 10.3% were attributable to CKD, but this figure increased to 17.5% among people with low socioeconomic status. The researchers also found that people who regularly used Chinese herbal medicines had a 20% increased risk of developing CKD. The study was published in The Lancet. Rates of childhood obesity, which had been rising for more than two decades, appeared to have hit a plateau in 2006. The finding, based on data gathered from 1999 to 2006 by the CDC, was published in May in the Journal of the American Medical Association. The study said that it was unclear whether the slowdown in childhood weight gain was permanent or the short-term result of public antiobesity efforts such as curbing junk food and increasing physical activity in schools. Even if the trend held, 32% of American schoolchildren remained overweight or obese, doctors noted. The data came from thousands of children who had taken part in the National Health and Nutrition Examination Surveys, which had been compiled by the National Center for Health Statistics at the CDC since the 1960s. The plateau followed years of weight gain among American children. In 1980, 6.5% of children from ages 6 to 11 were obese, but by 1994 that number had climbed to 11.3%. The rate had jumped to 16.3% by 2002 and in 2006 had stabilized at about 17%. (KEVIN DAVIS)


Viewing all articles
Browse latest Browse all 5

Latest Images

Trending Articles





Latest Images