Wednesday, August 29, 2012

Bone Density Scans are Over-Recommended in Younger Patients

The American Academy of Family Physicians currently recommends that its members not do bone density scans (dual-emission X-ray absorptiometry - DEXA) to test for bone loss in healthy women who are under the age of 65; for men the age is 70. And yet, many family practice physicians and internists are doing the scans on their younger patients anyway.

The reasons for the disconnect are complex. Many physicians own the X-ray machines used to do bone density scans and therefore they have a financial incentive to recommend a scan. Others simply may not know of the latest recommendations or are taking a defensive medicine approach – the more tests, the better. But it’s not always the physician’s fault; sometimes the patient is aware of the dangers of osteoporosis and asks to be tested, without knowing whether the test is really appropriate for his/her situation.

Knowing when to use medical tests (and when not to) is not always easy. At the very least, it requires a knowledgeable physician and good communication between doctor and patient.

On the flip side, there are indications that bone density scans are being under-utilized in older patients; the ones who actually need them. In recent years there has been a decline in bone density scans under Medicare due to cuts in Medicare Part B reimbursements.

Monday, August 27, 2012

Older Fathers Pass On More Mutations

A recent study shows that men pass on more random mutations to their offspring than do women – about four times more, in fact. In addition, the number of mutations rises with the man’s age, approximately doubling from age 20 to age 40. In contrast, the number of mutations women pass on to their offspring is essentially unaffected by maternal age.

Actually, this makes sense. Women typically are born with all the eggs they’ll ever have, so there’s essentially no chance for the eggs to undergo genetic change throughout her life. In men, the cells that eventually lead to sperm continue to divide throughout a man’s life. As these cells divide they may accumulate mutations that are passed on.

The observation fits with a previous observation, published in April in Nature, that older men are more likely to have a mutation in a specific gene linked to autism and to father children with autism.

Wednesday, August 22, 2012

Human Genes ARE Patentable (At Least for Now)

In yet another installment of the long-standing battle, over whether human genes are patentable, the U.S Court of Appeals for the Federal Circuit has affirmed its earlier ruling that human genes ARE patentable once they are isolated and sequenced. But first they had to get past a Supreme Court ruling that “products of nature” cannot be patented.

A company called Myriad Genetics believed that it held valid patents on two important gene variants; the BRCA1 and BRCA2 genes that confer an especially high risk of breast cancer in women. Myriad Genetics argued successfully this time around that once a gene has been isolated and sequenced, it is in a form that never appears in nature! Technically, they are right; in nature a gene is always associated with histone proteins and is always part of a much larger DNA sequence that constitutes a chromosome. An isolated and fully sequenced gene, according to Myriad Genetics, is a chemically altered structure produced by man, and hence is patentable. The Court of Appeals agreed. An analogy would be that a baseball bat (a form invented by man) is patentable, but a tree trunk (a “product of nature”) is not.

Not everyone likes the ruling, for it appears to stand on a technicality; that “in nature” genes are associated with histone proteins. Everyone knows that it’s knowing and controlling the nucleotide sequence of genes that’s going to be important commercially – not the presence or absence the histones. But for now the ruling stands, and Myriad Genetics can continue to control the market for BRCA1 and BRCA2 gene test kits. And that’s the point of patents, isn’t it? Patents provide the incentive for companies to spend money developing important new technologies, such as tests for a high-risk genes.

Thursday, August 16, 2012

Semenya Takes the Silver Medal

After a slow start that had her running dead last at the 200-meter mark, Caster Semenya turned on the afterburners and blew past six other runners, placing second and earning the silver medal in the 800-meter event at the summer Olympic Games in London this month.

Ms. Semenya, as you may recall, was the young woman whose gender was questioned after winning the 800-meter event at the world championships in 2009. After her win she was hustled out of the stadium before she could even finish her victory lap. She was out of competition for nearly a year while the International Association of Athletics Federations (IAAF), international track and field’s governing body, “decided” whether she could compete as a woman. Ultimately the IAAF decided that she could compete, but the incident caused enormous embarrassment to the 18-year-old Semenya; embarrassment that could have been avoided if the IAAF had had a gender decision policy in place and made its gender determination before the event, not after.

Following her second-place finish at the Olympic Games, there have been rumors that Ms. Semenya might have deliberately held back, taking second place to avoid re-igniting a controversy had she won the gold. Really? If you had survived an embarrassment like Ms. Semenya’s and then trained hard for two years for the Olympic Games, would you be able to deliberately not go for the gold? Somehow I doubt it.

Ms. Semenya’s gender didn’t become an issue at these past Olympic Games. The Olympic Committee planned to rely on a test of testosterone levels, but said they would only test female athletes if the athlete’s performance was questioned. Neither the IAAF nor the Olympic Committee has a policy of screening all female athletes equally beforehand, in order to avoid publicly embarrassing athletes who ultimately are not allowed to compete as women.

Monday, August 13, 2012

Obesity and Kidney Donation

Over 90,000 patients with advanced renal failure are waiting for a suitable kidney for a transplant. There are simply too few cadaveric kidneys available, and not enough suitable living donors, either.

Live donor kidney donation is considered safe for persons who are in good health. Long-term follow-up studies of persons who donated kidneys as long as 50 years ago have shown past donors live just as long as one would expect. To ensure that donors are not put at risk, potential kidney donors are screened for good health before they are allowed to donate.

Persons who are obese may be rejected as potential kidney donors even though they are otherwise in good health. That’s because obesity is a known risk factor for kidney disease later in life. There are no hard-and-fast weight limits to be allowed to donate a kidney because no one knows whether donating a kidney would actually increase an obese person’s chances of kidney disease later in life. Nevertheless, many kidney transplant centers aren’t willing to take the risk. More than half of all kidney transplant centers set a Body Mass Index (BMI) of 35 as an upper limit for an acceptable donor; 10% set the limit even lower, at a BMI of 30.

According to a presentation at a recent clinical meeting of the National Kidney Foundation, one transplant center found that 37% of its potential living kidney donors were obese (BMI>30) and another 22% were morbidly obese (BMI>35). Although the morbidly obese potential donors received nutritional counseling and follow-up, fewer than 15% lost enough weight and eventually were allowed to donate a kidney.

Obesity is on the rise in this country. It’s a shame that the potential pool of living kidney donors, never large enough to begin with, may shrink even further with the rise in obesity.

Sunday, August 5, 2012

Texting While Driving –“Don’t Do It”

While driving home from college last January, Texas student Chance Bothe texted a friend, “I need to quit texting because I could die in a car accident and then how would you feel… ”.   His last text was “b right there”, according to KHOU11 News in Houston.  Moments later he drove off a bridge and into a ravine.  He suffered brain injuries, a broken neck, broken facial bones, a punctured lung, and too many bones to count.

Young Mr. Bothe was released from the hospital last week after six months of reconstructive surgery and all kinds of therapy, including speech therapy to learn to talk and physical therapy to regain his ability to walk.   He still has a long road of recovery in front of him, but he’s recovered enough to want to send a message to others.   He says about texting while driving, “Don’t do it. It’s not worth losing your life.”

Mr. Bothe’s tragic story is just one of a litany of such stories since texting became common.  Laws restricting texting while driving are either on the books or are being considered in most of the 50 states. And for good reason.

Wednesday, August 1, 2012

Cancer Treatment Can Sometimes Cause Cancer

The two primary treatment methodologies for cancers – radiation and chemotherapy – are about as subtle as a sledgehammer. The goal of both treatments is to damage and thus to wipe out the rapidly-dividing cancer cells, but in the process they may also damage or kill normal cells undergoing growth and division. That’s why cancer patients lose their hair and feel nauseous after treatment; the treatments have damaged the cells of hair follicles and the cells that line the digestive tract.

It’s now known that sometimes chemotherapy and radiation can lead to additional cancers that are caused by the treatments themselves. That’s apparently what happened to Robin Roberts, the anchor of the “Good Morning America” show. Ms. Roberts received radiation and chemotherapy treatment in 2007 as part of her treatment for breast cancer. Now she’s been diagnosed with myelodysplastic syndrome (MDS), a potentially fatal blood and bone marrow disease that used to be called proleukemia.

Ms. Roberts’ MDS is called a secondary cancer – either a new, different primary cancer that comes after a diagnosis of primary cancer, or (more commonly) a cancer that has spread from its primary site to other parts of the body. Ms. Roberts’ MDS is of the first type. Although it could have been just an unlucky unrelated event, statistically its much more likely to have been caused by her prior cancer treatment.

No doubt about it, chemotherapy and radiation therapy are hard on the body. But they’re getting better every year. Researchers are finding better ways to target cancer cells specifically, thereby sparing normal cells the damage that comes with traditional cancer therapy. Hopefully, that will reduce the number of secondary cancers caused by cancer therapy itself, like Ms’ Roberts’ MDS.

Ms. Roberts plans to have a bone marrow transplant sometime within the next two months. Her sister is likely to be the bone marrow donor, according to news reports.