From the Townsend Letter for Doctors & Patients
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Macular degeneration is a condition in which the macula, a place near the center of the retina with the greatest visual acuity, begins to deteriorate. In Women's Health Letter, Nan Kathryn Fuchs, PhD suggests ways to prevent or retard the progression of macular degeneration. Nutrients, especially the carotenoids, protect the retina and prevent deterioration. The carotenoids lutein and zeaxanthin, which are in spinach, kale, and mustard or turnip greens, protect the retina from ultraviolet rays in sunlight. Edward Kondrot, MD, author of Healing the Eye the Natural Way, recommends 100-200 mg/day of lutein for people with macular degeneration. In addition to the carotenoids, other antioxidants such as bioflavonoids and vitamin C, glutathione, and selenium with vitamin E protect the retina from free radical damage caused by ultraviolet light as well as help remove waste products in the retina that contribute to macular degeneration. Taurine, zinc, and omega-3 fats are also needed for healthy eyes. How much of these nutrients can actually be absorbed by the body depends upon the digestive system; eating too quickly, too little hydrochloric acid, or too few enzymes can affect absorption.
Other measures that prevent sight loss (and promote general good health) include exercising and breathing deeply, reducing stress, and wearing sunglasses that block UV rays. If possible, smokers who are concerned about their eyesight should quit. Smoking contributes to macular degeneration because it uses up vitamin C, weakens blood capillaries, and increases damage to the retina from UV sunlight.
Fuchs, Nan Kathryn, PhD. Save Your Vision: Stop Macular Degeneration. Women's Health Letter. 2001 November; Vol. VII; pp. 1-3
One of the experimental drugs being studied is Genentech's rhuFab. Like many of the other new eye drugs, rhuFab inhibits the growth of blood vessels in the eye by blocking a growth-promoting protein called vascular epidermal growth factor (VEGF). Bausch & Lomb's Retisert, a rice-sized time-released steroid implant, and Eyetech's EYE001, which like rhuFab is injected into the eye, also block VEGF. A pill by Lilly that inhibits a cell's reaction to VEGF (LY333531) is designed to stop the progression of diabetic retinopathy.
All of the drugs are in early testing. Doctors estimate that about one-fourth to one-third of the people with early wet macular degeneration have experienced significant improvement in vision. One man quoted in the news article went from 20-400 to 20-50 in 7 months. For most of the other participants, the progression of sight loss is stopped, "at least temporarily.” Larger studies are needed to determine how long patients need to take the drugs, if the disease will return, and what risks and negative side effects occur with the drugs and repeated injections.
Haney, Daniel Q. Eye drug results outta sight. The Herald-Sun (Durham, North Carolina) 2002 July 2; pA1+
Hearing Loss Risk Factors
Although the article in Audiology HealthCare News does not speculate about the reason, studies have found a link between cardiovascular disease and hearing loss. A person with ischemic heart disease is eight times more likely to have hearing loss than a person of the same age without heart disease, according to a study by Susmano and Rosenbush (1988). Another study found that men with systolic blood pressure of 160 mm Hg or greater were 74% more likely to have significant hearing loss
Hearing Sensitivity in Adults Screened for Selected Risk Factors. Audiology HealthCare News 2002 Winter
Hereditary Hearing Loss
Although several genes affect hearing, researchers have identified GJB2 (gap-junction beta 2) as accounting for "up to 50% of hereditary pre-lingual severe-to-profound nonsyndromic hearing loss,” according to a study by W. McGuirt and R. Smith [Connexin as a Cause of Hereditary Hearing Loss. Amer J of Audiology (Dec. 1999), 8: 93-100]. This gene determines the function of the protein Connexin 26 (Cx26), which maintains high potassium concentrations in the cochlea's scala media. About 2.5% of the population in Midwestern United States carry a mutated form of this gene.
Genetic testing for Cx26 is available in the United States. The test may help clarify the etiology of pre-lingual severe to profound sensorineural hearing loss for some people. Most of the testing is done, however, on people with no family history of hearing loss, according to this article. W. McGuirt and R. Smith recommend that appropriate explanations and counseling accompany the genetic test so that participants understand what the results mean. If one parent has severe congenital sensorineural hearing loss caused by a Cx26 mutation and the other does not carry a form of the mutated gene, it is very unlikely that any of their children will be born with impaired hearing. All of their children, however, will carry the mutated gene. On the other hand, if two hearing parents each carry a mutated Cx26 gene, each of their children has a 25% chance of being born with severe to profound hearing loss. In addition, the couple's normal-hearing children have a 66% chance of carrying the mutated Cx26 gene.
Connexin 26 as a Cause of Hereditary Hearing Loss. Audiology HealthCare News 2001 Autumn.
Laser Eye Surgery
Dr. Battat says that surgeons must screen prospective clients carefully. She tests tear production and refuses to operate on persons with extremely dry eyes. According to the Washington Post article, a Chevy Chase corneal specialist named Roy Rubinfeld questions the accuracy of the tear production test that Dr. Battat uses; but he does ask potential clients if they can tolerate contact lenses and if they have dry eyes. He said that Dr. Battat's research is "…probably the best discussion of something experienced Lasik surgeons have been noting – that dry eyes, once thought to affect a fraction of Lasik patients, are a much more common problem post-operatively and can occasionally be serious.”
Dry eyes are not the only possible complication of Lasik surgery. Worsened vision, even blindness, are also possible. A press release from Aubrey Haznar at Lawyers Weekly USA states "suits involving laser eye surgeries have increased dramatically and if this trend continues, it could trigger a wave of class action suits similar to the thousands of suits by those who claim they were harmed by asbestos.”
Boodman, Sandra G. For Some Lasik Patients, No More Tears. Washington Post 2001 July 10; p HE05
Haznar, Aubrey. Laser-Eye Surgery Suits on the Rise Nationally Botched Procedures Are Triggering a Wave of Litigation (a summary of the Lawyers Weekly USA article, dated December 13, 2001); www.LawyersWeeklyUSA.com
Success depends upon the number of functioning auditory nerve fibers and the presence of established nerve pathways that permit the brain to decode the electrical impulses generated by the implant. Without stimulation, nerves in the central auditory pathways degenerate. Consequently, persons with profound hearing loss for many years have less success with implants than those who have the operation shortly after deafness occurs or, in the case of children, is determined. Dr. Langman writes: "Most patients who have had a cochlear implant have improved environmental sound detection. Communication ability is generally improved. This ranges from improved lip reading to the understanding of speech without visual clues.”
In most cochlear implant surgeries, an external component is implanted subcutaneously into the skull. The external component consists of a microphone, a processor that changes the sounds picked up by the microphone into electrical signals, and an antenna that transfers these signals to the implant's internal components. The internal components transport the electrical signals to the auditory pathways of the central nervous system. The internal components are placed within the temporal bone, requiring a mastoidectomy and a cochlecostomy (an opening into the cochlea). Dr. Langman says that patients can usually go home the day after surgery and that "Typically, no cosmetic deformity is noticeable following this type of surgery once all healing takes place.” The implant is activated by programming each electrode about a month after surgery. Surgical risks include possible damage to the facial nerve and the balance portion of the inner ear.
The 2001 documentary film Sound and Fury, which was nominated for an Academy Award, shows that cochlear implants are extremely controversial among the deaf community. Choosing whether or not to have implants impacts a deaf person's identity, community relations, and relationship with deaf culture in ways that few hearing persons can imagine. Many in the deaf community fear that if deaf persons choose to hear, ASL (American Sign Language), a unique and expressive language with its own idioms and syntax, will disappear, as will deaf culture. PBS broadcast Sound and Fury during its 2001-2002 season. Its website (www.pbs.org/wnet/soundandfury) has information about cochlear implants and the debate on their effects.
Langman, Alan W., MD. Cochlear Implants. Northwest Neuroscience Institute Journal 2001Autumn; Vol. 8: pp.1-2
Insulin Resistance & Periodontal Disease
The researchers analyzed data on periodontal status, body mass index (BMI), fasting insulin and fasting glucose from 10,836 people enrolled in the Third National Health and Nutrition Examination. The researchers considered people with a BMI over 27 to be overweight. Body mass index (a ratio of weight to height) is obtained by dividing weight in kilograms by height in meters squared. Periodontal disease was defined as an average loss of gum attachment of more than 1.5mm. People with diabetes or with less than six teeth were excluded from the UB dental study. Dr. Sara Grossi, the director of the UB Periodontal Disease Research Center and the study's lead author, said: "Acute infections cause metabolic disturbances and periodontal disease is one of humankind's most common chronic infections…. In this case, we think bacteria from gum disease may interfere with fat metabolism, leading to elevated LD, cholesterol and total cholesterol. This has been shown in small case-control studies and animal studies.”
The title of the University's press release, "UB Dental Researchers Find Obesity Related to Gum Disease” is misleading. The study found that overweight people with a high insulin-resistance index, not overweight people in general, were more likely to have severe periodontal disease.
UB Dental Researchers Find Obesity Related to Gum Disease. 8 April 2000. www.sdm.buffalo,edu/news/20000408_obesity.html
Atherosclerosis Risk & Retinal Arteriolar Narrowing
The researchers took retinal photographs from 9648 women and men, ages 51 to 72, who were part of the ongoing population-based Atherosclerosis Risk in Communities Study that began in 1987-89. At the time of the photographs (1993-95), these people did not show signs of coronary heart disease. The researchers determined retinal arteriolar narrowing by measuring individual arteriolar and venular diameters, via digitized photographs, and calculating a summary arteriole-to-venule ratio (AVR). In earlier studies, they had found that this ratio corresponds to "markers of inflammation and endothelial dysfunction, but is unrelated to measures of atherosclerosis (eg. Carotid IMT).”
During the follow-up period (an average of 3.5 years), 84 women and 187 men had coronary heart disease (CHD) events. After controlling for numerous risk factors (diabetes, cigarette smoking, plasma lipid levels, arterial blood pressure), the researchers found that a mean decrease in the AVR (indicating narrowing) corresponded to an increased risk of any coronary heart disease incident in women, but not in men. Unlike men, women with chest pain tend to have normal coronary arteries. They also have higher mortality rates after a myocardial infarction and poorer results with coronary artery bypass surgery than men do. The authors stated: "We are unable to offer an adequate explanation of the strong sex difference or, in particular, of why a lower AVR, as an indicator of more severe coronary microvascular disease, is unrelated to risk of CHD in men. We can only note that this sex difference is consistent with the often-made clinical observation that angina without angiographic stenosis is much less frequent in men than in women.”
Wond, Tien Yin, MD, MPH et al. Retinal Arteriolar Narrowing and Risk of Coronary Heart Disease in Men and Women. JAMA 2002 March 6; Vol 287; pp.1153-1159
Although scientists have cloned cows, pigs, mice, sheep, and goats since 1996, a cat was only recently cloned by Mark Westhusin and colleagues at Texas A&M University. To make "Cc” the researchers fused cells from another cat named Rainbow with unfertilized cat eggs, emptied of genetic material. The embryos were then implanted into surrogate mothers. It took several tries before a viable cloned kitty entered the world. Interestingly, Cc does not look exactly like Rainbow even though genetically they are identical. The researchers attribute the difference in markings to random factors such as womb environment.
The technology for cloning is still unpredictable, but scientists are confident that it will improve. Right now, cloned animals tend to have more health problems than their prototypes: Dolly the sheep developed arthritis at an early age, and cloned mice tend to develop obesity and have a shorter lifespan. Nevertheless, bioengineers have big plans. A company called Transgenic Pets is trying to clone cats that are free of the protein that can cause allergic reactions in people. Flea-repellent pets, dogs genetically-engineered for police work or to help the disabled, and attack dogs with superaggressive genes (some dog breeders have already managed to do that – without biotechnology) are among the other designer companion animals that researchers have in mind. Others see cloning as the answer to preserving species that will soon be extinct.
Nell Boyce points out some of the ethical questions that arise from cloning pets. For example, what happens to the animals that donate eggs and act as surrogate mothers? Genetic Savings & Clone reportedly finds homes for these animals. But what do other companies do? Ethicist Lori Gruen from Wesleyan University sees "exploitation of grief as a serious problem.” She says that these companies "are taking advantage of people who intellectually may know they're not getting their animal back but emotionally they think they're getting their animal back.” She says: "One of the dangers of cloning a pet for a child is simply to say, "Here, let's replace this,” as if you don't grieve for the loss. How does that translate when Dad dies?”
Boyce, Nell. Pets of the Future. US News & World Report 2002 March 11; pp. 46-53
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|February 11, 2003|