Friday, May 30, 2008
So why isn’t there something like this for the eye, to restore vision to the blind?
The most common causes of blindness arise from degeneration of the retinal cells that detect light, the photoreceptor cells. When these cells die, the remaining nerve cells in the retina survive for a while before they too die.
Several labs are building chips that can be inserted behind the retina, where the photoreceptor cells are in the normal eye (Tübingen, Tokyo Institute of Technology). These implants stimulate the surviving nerve cells, mimicking the photoreceptor cells.
Other labs want to tack (yes, tack) their implants onto the front of the retina (Harvard & MIT, John Hopkins & USC).
The visual scene is captured either by a camera attached to a pair of glasses, which transmits the signals to the implant in the eye, or by photocells on the chip itself.
Retinal implants are being tested in patients, with moderate success. Patients who were completely blind are able to make out bright light sources and some movement.
Great, right? Seeing vaguely is better than not seeing at all, and certainly makes daily life easier. But retinal implants may never advance to the level of the cochlear implants.
This is because the retina is far more complex than the cochlea. The cochlea pretty much just encodes frequency (pitch) and intensity (loudness). All the rest, including the location of a sound source, is processed in the brain. The retina, on the other hand, does a huge amount of processing before sending its signals to the brain.
Object location, brightness, orientation, motion, and color are all encoded in the retina. So the electrical signals that the retinal implant produces need to include all of this information. But retinal scientists are only just beginning to understand how all this works.
These problems may be solved eventually, and in the meantime, people with implants are happy to have 16-pixel vision.
But this month, Botond Roska, of the Institute for Biomedical Research in Basel, presented a brilliant new idea for restoring vision to the blind (Nature Neuroscience 11:667-675).
His idea was to confer the ability to detect light onto the nerve cells which survive after the photoreceptor cells die. His team did this by introducing the gene for a light-sensitive protein into a specific group of nerve cells in the retina.
This protein builds channels in the membrane of the cell. When the channel is stimulated by light, it opens, allowing charged particles to flow into and out of the cell. This flow of charges is an electrical signal, and it is the same as the signal that these cells produce in the normal retina when they are stimulated by photoreceptor cells.
Dr. Roska’s team tested their idea in blind mice. When these mice were treated with the gene for the light-sensitive channel protein, their vision was restored with relatively high acuity.
This project is in its infancy, and there are a lot of problems to be worked through. For example, normal room lighting is too dim to stimulate the channels, so some sort of amplifying system will have to be worked out.
It may be another 50 years before scientists are able to restore vision of reasonable quality to blind people, but I’d be willing to bet that when it does happen, it’ll be by gene targeting and not by retinal implantation.
Monday, May 26, 2008
How many people do you know who eat a balanced, healthy diet? I mean the kind with 5+ servings of fruits and veggies per day.
To massage our bad consciences, we swallow multi-vitamin pills, hoping this will make up for skipping the salad. But how much do these vitamin supplements really help?
One recent study, which flew through the media, claimed that vitamins A and E increase the risk of death. That study didn’t actually involve any experiments or subjects; it was a statistical analysis of data from other people’s experiments, all of which had already shown that vitamin supplements have either no or negative effects on life expectancy. So the study didn’t actually present anything new.
Nevertheless, if you are taking vitamins hoping they will make you live longer, you can stop now. But if you are worried that taking vitamins will kill you, just keep in mind that vitamin supplements are intended to supplement the diet. If you eat a balanced diet, you don’t need them. And too much of the fat-based kind (A, D, E, and K) can be toxic.
So, vitamins won’t make us live longer, but can they make our short stay on Earth healthier and happier?
How can these benefits be measured scientifically? Ideally, the effects of vitamins would be studied by monitoring two large groups of people: one group gets vitamins every day, and the second group placebos. The catch is, all members of both groups need to eat the same foods and get the same amount of exercise.
Where to find hundreds of people whose diet and activities are the same every day? Prisons!
One of the first studies to examine the effects of vitamin supplements came out in 2002. A team of researchers headed by C. Bernard Gesch, of the
Neither the subjects nor the prison guards who distributed the pills knew who was receiving the supplements and who got placebos. The study was also randomized, to eliminate effects of ethnic or social factors.
Daily intake of vitamin supplements reduced antisocial behavior, including violence, by 35%. These improvements showed up after just two weeks.
A new 3-year study is starting in the
Professor John Stein of
What does this mean for us? Vitamin supplements won’t extend our lives, but they may make life more pleasant for those around us.
Monday, May 19, 2008
Olga Kharif, in Tech News World (May 5), gives us one more reason to love the iPhone. As if we needed another reason!
The software company Life Record is developing ways to let physicians view medical records, including electrocardiograms and brain scans, using the iPhone. Their software also lets doctors send and receive patient records by SMS, and order prescriptions.
For those of us who are not doctors but want an excuse to buy an iPhone, the company is also developing software for patients. For $50 a year (which is nothing compared to the cost of the 2-year contract you have to sign when you buy the phone) patients can have access to their own records via iPhone. This could be handy when visiting a new doctor or specialist.
iPhone users aren’t the only ones who will benefit from new medical technologies. Kharif reports that 17 of the 30+ health care projects funded by Microsoft Research involve cell phones. And sales of phone applications for medical professionals are expected to more than double by 2011.
Researchers hope that mobile phones will help reduce the frequency of medical errors. Gentag is developing wireless disposable skin patches which store the patient’s medical records. The patches are equipped with a chip that transmit to a mobile phone. If the patient is about to receive medication, the patch can warn of any allergies. The patch will also allow patients’ blood glucose and temperature to be monitored by phone.
Another life-saving idea, being developed at the
A similar application has been introduced in
Wednesday, May 14, 2008
Today’s marketing experts are so savvy, they can get us to want to eat bacteria, just by dropping buzz words like “numerous health benefits,” “clinically proven,” and my personal favorite, “boost the immune system.”
We don’t mind eating what we would normally call germs when they are given the scientific-sounding name “probiotics.”
Whether the stuff actually works, or consumers are being duped, is hard to say, but sales of food products containing probiotics have taken off in the last 2 years. One market leader, Activia by Dannon, had a 48% increase in sales in 2007, according to Brendan Borrell in the LA Times (May 12, 2008).
What are probiotics? The Food and Agriculture Organization of the United Nations defines probiotics as "live microorganisms that when administered in adequate amounts confer a health benefit on the host." This leaves very little room for skepticism, since by definition, probiotics are good for you.
A common source of probiotics is yogurt. Companies are winning over consumers by promising that their yogurt regulates the digestive system (Activia) and helps “strengthen your body's defenses” (DanActive).
Can probiotic products really deliver these benefits? Companies that sell these products conduct research to support their promises, and surprise, surprise! Company-funded research shows positive effects on the immune (Culturelle) and digestive systems (Procter & Gamble and Dannon).
Consumers should be aware that there are many different strains of bacteria. Different strains can have different effects. Lactobacillus reuteri RC-14, for example, can fight vaginal infections; Lactobacillus casei, found in DanActive, has been shown to reduce diarrhea in children; and Bifidobacterium animalis, used in Activia, reduces constipation.
Some companies boast benefits which were demonstrated in a completely different strain. To make it even harder for consumers to inform themselves, companies often use scientific-sounding trademark names for their products.
Another thing the companies don’t print on the labels is that you have to eat a LOT of yogurt to get the promised benefits. Dannon’s 2002 report claimed that women who ate 3 cups of Activia yogurt per day exhibited more frequent bowel movements than when they ate the same amount of yogurt without the probiotic.
Three cups per day!
Huge amounts of probiotic yogurt are probably necessary because plain yogurt itself, without probiotics, helps to regulate the digestive system.
In order to be called yogurt in the
Normal yogurt is also good for people with lactose intolerance, since the bacteria produce the enzyme that breaks down lactose.
Thursday, May 8, 2008
Even diluted, bleach is not as harmless as many people think. More than 85% of American households use it, according to the American Chemistry Council.
One major use of bleach is for laundry. Quite handy for removing stains, but regular use should not be necessary if you have a good detergent.
Bleach is also commonly used for disinfection in the kitchen or bathroom. But many users don’t know that prolonged exposure is required to kill germs. Clorox recommends soaking for 5 minutes. Just splashing bleach on the cutting board isn’t going to do it. But it could make you sick.
Bleach is toxic. It causes skin and eye irritation, breathing problems, and asthma.
Studies have shown that children whose parents frequently use bleach are much more likely to develop persistent wheezing, which can lead to asthma. It’s not clear whether the bleach itself causes the wheezing, or whether extreme cleanliness is at fault. Children who grow up without being exposed to germs end up with weak immune systems, which can lead to asthma or allergies.
When combined with other common, household substances, such as ammonia, toilet bowl cleaners, or vinegar, bleach produces a poisonous gas. The Washington State Department of Health warns that prolonged exposure to this gas can damage the lung tissue, causing severe breathing difficulties, pneumonia, or even death. If you use bleach to clean your toilet, don’t pour any other cleaners in until you’ve flushed the bleach out.
According to the American Association of Poison Control Centers, more than 20,000 children were reported to have been exposed to bleach in 2006 (http://www.aapcc.org/annual.htm). In comparison, approximately 40,000 cases of salmonella infection are reported each year, according to the Center for Disease Control.
If you do use bleach, be smart about it. Make sure it is clearly labeled and kept out of the reach of small children. Dilute it, rinse with lots of water afterwards, and either let it air dry, or dry with a clean towel.
It doesn’t make sense to splash bleach on the utensils, then dry them with the towel that’s been hanging there all week. And my favorite: people who bleach their cooking utensils, but use their dish sponge on the floor.
If you’re worried about germs, (or if you swear by bleach but order your burgers rare) then check out the Center for Disease Control and Prevention’s guidelines for preventing salmonella infection: http://www.cdc.gov/nczved/dfbmd/disease_listing/salmonellosis_gi.html.
Monday, May 5, 2008
But what if those incontinence pills react badly with the dementia therapy? A team of doctors headed by Kaycee Sink at the Wake Forest University in North Carolina sifted through data from over 3,500 nursing home patients to find the answer to this question. Their study appeared in the May edition of the Journal of the American Geriatrics Society.
Dementia patients are often prescribed cholinesterase inhibitors to slow down the decline in cognitive function and their ability to perform daily tasks. These drugs work by increasing the amount of a substance called acetylcholine, which is underproduced in the brains of dementia patients.
Patients with dementia often also suffer from urinary incontinence, and the drugs typically given for this condition do the opposite of what cholinesterase inhibitors do: incontinence drugs are anticholinergics, which reduce the amount of acetylcholine. So in theory, the drugs for incontinence should counteract the dementia treatment.
Prescribing these two opposing medications is common practice, even though nobody really knows how the two drugs interact: Dr. Sink and her colleagues found that at least one in ten nursing home residents receive both cholinesterase inhibitors and anticholinergics.
The researchers examined the medical data from patients who had been taking either the two drugs together, or just the cholinesterase inhibitors alone, for at least two years. For both groups, they looked at the patients’ ability to perform normal activities of daily living.
Both groups showed a decline in mobility, as expected for dementia patients. Perhaps not surprisingly, the decline in mobility was 50% faster in patients taking both drugs together than in those that didn’t take the anticholinergics. This translates to a change from requiring limited assistance for daily activities to being completely dependent on care givers within one year.
This poses a difficult dilemma for nursing home doctors: treat the dementia symptoms or the incontinence? And surely these aren’t the only two ailments with conflicting treatments.
Thursday, May 1, 2008
Wouldn’t it be nice to get the trucks off the streets? Dr. Dietrich Stein, at the Ruhr University of Bochum, Germany, has come up with a clever solution. It’s called CargoCap, and it’s an innovative system for transporting goods in high-traffic downtown areas by underground pipelines. Goods are loaded into the Caps, which are independent, computer-operated vehicles. A Cap can hold two euro-pallets, which are the common cargo transport units in
The advantages of this system are obvious: reductions in traffic, pollution, noise, accidents, and road expansion. The founders have even come up with a way to build the system without disturbing everyday life aboveground. They plan to use an underground, computer-controlled pipe jacking system to precisely drive the pipes into place. Displaced earth is automatically returned to the surface by way of the pipes. The pipe jacking system and small diameter of the pipes allows CargoCap to be implemented near existing infrastructure, and the system can easily be expanded to meet increases in demand.
So far, CargoCap only exists as a model. Dr. Stein and his team are planning to start a company to build the Caps, but realization of the CargoCap system in a German city will take many years, as the political machinery stands in the way.
Intrigued? See www.cargocap.com.