A French company called Carmat has developed a new artificial heart that may be a significant improvement over current models. Current models of artificial hearts tend to cause blood to clot, because blood is in direct contact with their metal or plastic inner surfaces. In the Carmat heart, all surfaces of the heart in direct contact with blood are lined with tissue derived from the pericardial sac of cows. The heart is a sophisticated pumping device controlled by sensors, microelectronics and software. It is powered by external batteries, making regular battery changes feasible. Testing of the heart in human patients is likely to begin in several European countries as early as this year.
Artificial hearts have entered the clinical testing phase before, only to prove disappointing later. The big stumbling block has been the tendency of all previous artificial hearts to cause blood to clot. Achieving a high long-term success rate in human patients has proven frustratingly elusive. Current artificial hearts are generally used only to keep the patient alive until a proper human donor heart is available.
It’ll be years before we know whether the Carmat heart will be the first implantable artificial heart that can be used successfully for the long term. We’ll be watching this one closely.
Friday, July 26, 2013
Thursday, July 18, 2013
A New Class of Cholesterol-Lowering Drugs
Researchers have discovered a rare gene mutation that results in very low low-density lipoprotein levels (LDL is the “bad” cholesterol). So far, only two people have been identified who are homozygous for (i.e. have two copies of) the mutated gene. Both people have LDL levels around 15 mg/dl. An LDL of less than 100 is considered optimal; over 160 is classified as high.
LDL is considered to be a major contributor to atherosclerosis and thus to heart disease and strokes. The discovery that a genetic mutation can result in very low LDL levels has triggered a rush by several major drug companies to produce a drug that mimics the effects of the mutation. At least three drug companies already have drugs in the testing stage. The drug companies view anti-cholesterol drugs as potential blockbusters. From the perspective of a drug company, drugs that are taken long-term for chronic conditions are far better profit-generators than drugs that are taken only for a brief period to cure a disease or condition (such as antibiotics, for example). In addition, LDL-lowering drugs are likely to be expensive.
If/when LDL-lowering drugs are approved, who should take them? Aside from people with high LDL levels, would people with what are currently considered optimal LDL levels also benefit from taking these drug?
LDL is considered to be a major contributor to atherosclerosis and thus to heart disease and strokes. The discovery that a genetic mutation can result in very low LDL levels has triggered a rush by several major drug companies to produce a drug that mimics the effects of the mutation. At least three drug companies already have drugs in the testing stage. The drug companies view anti-cholesterol drugs as potential blockbusters. From the perspective of a drug company, drugs that are taken long-term for chronic conditions are far better profit-generators than drugs that are taken only for a brief period to cure a disease or condition (such as antibiotics, for example). In addition, LDL-lowering drugs are likely to be expensive.
If/when LDL-lowering drugs are approved, who should take them? Aside from people with high LDL levels, would people with what are currently considered optimal LDL levels also benefit from taking these drug?
Monday, July 15, 2013
When Should the Umbilical Cord be Severed?
It is standard practice when babies are born to clamp the umbilical cord immediately and then cut between the clamps, severing the connection between mother and infant in the first minute after birth. It has been done that way for decades, in part because it was believed that doing so reduces the risk of hemorrhage in the mother.
Recent evidence suggests that it may be better to delay cutting the cord for a minute or two after birth. After reviewing the outcomes of more than 3,900 women-infant pairs in 15 different previous studies, the authors of a recent study concluded that delaying cutting the cord did not increase the risk of maternal hemorrhage significantly. On the other hand, delaying cutting the cord for just several minutes resulted in improvement in several measures of infant health; a higher birth weight, a higher hemoglobin concentration several days after birth, and a reduced likelihood of iron deficiency at 3-6 months. The only negative was that delaying cutting the cord slightly increased the tendency for jaundice in the infant. Overall, the results suggest that in many normal deliveries, delaying clamping the cord for just a minute or two is probably beneficial overall.
Why would delaying cord clamping for such a short time be beneficial? The most likely explanation is that immediately after delivery the rate of cord blood outflow from the infant declines relative to inflow to the infant. So in that first minute or two, the infant gains a significant amount of blood from the mother in preparation for an independent life. Estimates are that the infant may receive as much as a third of its blood supply in that crucial first minute or two after birth.
Recent evidence suggests that it may be better to delay cutting the cord for a minute or two after birth. After reviewing the outcomes of more than 3,900 women-infant pairs in 15 different previous studies, the authors of a recent study concluded that delaying cutting the cord did not increase the risk of maternal hemorrhage significantly. On the other hand, delaying cutting the cord for just several minutes resulted in improvement in several measures of infant health; a higher birth weight, a higher hemoglobin concentration several days after birth, and a reduced likelihood of iron deficiency at 3-6 months. The only negative was that delaying cutting the cord slightly increased the tendency for jaundice in the infant. Overall, the results suggest that in many normal deliveries, delaying clamping the cord for just a minute or two is probably beneficial overall.
Why would delaying cord clamping for such a short time be beneficial? The most likely explanation is that immediately after delivery the rate of cord blood outflow from the infant declines relative to inflow to the infant. So in that first minute or two, the infant gains a significant amount of blood from the mother in preparation for an independent life. Estimates are that the infant may receive as much as a third of its blood supply in that crucial first minute or two after birth.
Wednesday, July 10, 2013
Increased Incidence of Melanoma in Young Women
The incidence of melanoma has risen dramatically in young persons in the past 40 years, especially in young women.
Researchers at the Mayo Clinic compiled data for the incidence of melanoma in persons aged 18-39 between 1970 and 2009 in a single county in Minnesota. They found that the incidence of melanoma has increased steadily each decade since the 1970s: the incidences were 4.8 (cases per 100,000 person-years) in the 1970s, 11.8 in the 1980s, 16.8 in the 1990s, and 30.8 in the 2000s (from 2000 to 2009). That’s more than a 6-fold increase in just 30 years.
One likely explanation for at least part the increase in reported cases of melanoma is that increased awareness of the disease has led to more frequent and more accurate diagnosis. Another is that the criteria for calling a lesion a melanoma has changed over time. However, when the authors broke the data down by gender they found that the incidence of melanoma differed dramatically between men and women; the incidence rose 4-fold in men, but 8-fold in women. In theory, a gender difference would not be explained by changes in awareness or definition over time.
Why is the incidence of melanoma increasing more in women than in men? The study’s authors speculate (and yes, it’s speculation at this point) its because young women use tanning beds more frequently than men. And despite what the advocates of tanning beds say, the UV rays emanating from tanning beds DO damage the skin and CAN lead to an increased risk of skin cancer.
Researchers at the Mayo Clinic compiled data for the incidence of melanoma in persons aged 18-39 between 1970 and 2009 in a single county in Minnesota. They found that the incidence of melanoma has increased steadily each decade since the 1970s: the incidences were 4.8 (cases per 100,000 person-years) in the 1970s, 11.8 in the 1980s, 16.8 in the 1990s, and 30.8 in the 2000s (from 2000 to 2009). That’s more than a 6-fold increase in just 30 years.
One likely explanation for at least part the increase in reported cases of melanoma is that increased awareness of the disease has led to more frequent and more accurate diagnosis. Another is that the criteria for calling a lesion a melanoma has changed over time. However, when the authors broke the data down by gender they found that the incidence of melanoma differed dramatically between men and women; the incidence rose 4-fold in men, but 8-fold in women. In theory, a gender difference would not be explained by changes in awareness or definition over time.
Why is the incidence of melanoma increasing more in women than in men? The study’s authors speculate (and yes, it’s speculation at this point) its because young women use tanning beds more frequently than men. And despite what the advocates of tanning beds say, the UV rays emanating from tanning beds DO damage the skin and CAN lead to an increased risk of skin cancer.
Friday, July 5, 2013
Smoking Rates Continue to Drop
Except for a brief uptick in 2008 and 2009, the rate of smoking among U.S. adults continues its long-term downward trend. The latest figures show that only 18% of adults are current smokers, down from 24.7% just 15 years ago.
Researchers believe that a number of factors are contributing to the decline. Cost is one – research shows that as the cost of cost of cigarettes goes up, rates of smoking go down. Public policies that create smoke-free workplaces, restaurants, and even outdoor parks are taking their toll, too. Although such policies don’t actually require that smokers quit or even smoke less, they tend to create a culture in which smoking is discouraged, rather than encouraged. Advertisements, particularly those that educate people about the marketing efforts of tobacco companies (getting people to dislike tobacco companies) or that show in graphic detail some of the devastating effects of smoking also may be contributing to the decline in smoking, at least among adults.
Will we ever get the rate of smoking down below, say, 5%? Not anytime soon, apparently. One group that does not seem to be very amenable to anti-smoking educational programs is kids. Getting them to never start smoking in the first place has proven to be a tough nut to crack.
Researchers believe that a number of factors are contributing to the decline. Cost is one – research shows that as the cost of cost of cigarettes goes up, rates of smoking go down. Public policies that create smoke-free workplaces, restaurants, and even outdoor parks are taking their toll, too. Although such policies don’t actually require that smokers quit or even smoke less, they tend to create a culture in which smoking is discouraged, rather than encouraged. Advertisements, particularly those that educate people about the marketing efforts of tobacco companies (getting people to dislike tobacco companies) or that show in graphic detail some of the devastating effects of smoking also may be contributing to the decline in smoking, at least among adults.
Will we ever get the rate of smoking down below, say, 5%? Not anytime soon, apparently. One group that does not seem to be very amenable to anti-smoking educational programs is kids. Getting them to never start smoking in the first place has proven to be a tough nut to crack.
Monday, July 1, 2013
Sarah Murnaghan had Two Lung Transplants
Well, it didn’t have to happen, but it did; Sarah
Murnaghan’s first lung transplant on June 12 failed almost immediately. She was
put back on the organ transplant list, and three days later she was given a second
set of adult lungs. Her condition is
improving now. But here’s the irony; in
all the talk in the past several weeks over the landmark case that she
represented (adult lungs given to a 10-year-old child), the pubic was unaware
that it was her second pair of lungs that have helped her to get better.
That fact only became widely known on June 28, nearly two weeks after the
second transplant.
The basic problem with transplanting adult lungs into children is that the lungs need to be “resized” to fit the child. It adds another level of risk to what is already a fairly risky procedure. That’s one of the reasons that the organization that oversees transplants, the Organ Transplant and Procurement Network (OTPN), had a policy of not approving adult lungs for transplant into children under 12 years old. But Sarah’s parents sued, and so the OTPN decided to keep its “Under 12 rule” but create a special review option for one year to consider exceptions on a case by case basis. So now we have a precedent that may embolden the parents of other needy children to sue for what they want. We should all be happy that young Sarah survived the surgeries and is doing well, but make no mistake; that means that the two sets of lungs didn’t go to someone else.
When it comes to such rare and precious resources as human organs, the decisions regarding who gets them are likely to remain contentious. This is worth talking about; who should decide, and how should they decide? The OPTN’s special review option is set to expire in one year unless the full board of directors votes to keep it. I’ll be interested to see what they do.
The basic problem with transplanting adult lungs into children is that the lungs need to be “resized” to fit the child. It adds another level of risk to what is already a fairly risky procedure. That’s one of the reasons that the organization that oversees transplants, the Organ Transplant and Procurement Network (OTPN), had a policy of not approving adult lungs for transplant into children under 12 years old. But Sarah’s parents sued, and so the OTPN decided to keep its “Under 12 rule” but create a special review option for one year to consider exceptions on a case by case basis. So now we have a precedent that may embolden the parents of other needy children to sue for what they want. We should all be happy that young Sarah survived the surgeries and is doing well, but make no mistake; that means that the two sets of lungs didn’t go to someone else.
When it comes to such rare and precious resources as human organs, the decisions regarding who gets them are likely to remain contentious. This is worth talking about; who should decide, and how should they decide? The OPTN’s special review option is set to expire in one year unless the full board of directors votes to keep it. I’ll be interested to see what they do.
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