How a Heart Fails

July 10, 2015

By Medical Discovery News

A heart

What exactly causes a heart to fail? It may come down to a simple protein, which scientists recently identified as having an important role in how a heart goes from weakening to failing.

Your heart is a strong, muscular pump slightly larger than your fist that pushes blood through your body. Blood delivers the necessary oxygen and nutrients to all cells in all the organs. Every minute, your heart pumps five quarts of blood. Human hearts have four chambers: two atria on top and two ventricles on bottom. Oxygenated blood leaves the lungs, enters the left atrium, moves to the left ventricle, and is then pumped out of the heart to the rest of the body. After it circulates, blood returns to the heart, enters the right atrium, moves to the right ventricle, and is then sent back to the lungs for a fresh dose of oxygen. Although your heart beats 100,000 times each day, the four chambers must go through a series of highly organized contractions to accomplish this.

Any disruption of this process can have serious consequences such as heart failure, which is clinically defined as a chronic, progressive weakening of the heart’s ability to circulate enough blood to meet the body’s demands. To compensate, the heart enlarges, which increases contractions and the volume of blood pumped. Blood vessels elsewhere in the body narrow to keep blood pressure normal. Blood can even be diverted from less important organs, ensuring more vital organs like the brain and heart are satisfied. However, such responses mask the underlying problem: the weakening heart, which continues to worsen. Ultimately, the body can no longer compensate for the heart, which is when it will start to fail.

Scientists at the University of California, San Diego School of Medicine studied the cellular changes in weakened hearts to better understand the transition from the compensatory stage, when it works harder to pump blood, to the decompensation, when it fails to pump blood sufficiently. They were especially interested in a RNA-processing protein called RBFox2 because it is involved in the heart’s early development and its continuing functions. When genes are expressed, DNA is transcribed into RNA, which is then processed and eventually used to make proteins such as RBFox2.

Sure enough, levels of RBFox2 were dramatically reduced in the hearts of mice with a condition similar to heart failure. Then they genetically engineered mice without RBFox2, which developed symptoms of heart failure. Not only are low levels of this protein connected to weakened heart muscle, without enough of it, the body cannot compensate and the heart declines more quickly. However, we still don’t know why levels of RBFox2 decline during the transition to the decompensatory phase of heart failure.

In the future, this research might be used to develop treatments that reverse the decline of RBFox2 and effectively slow or prevent heart failure.

For a link to this story, click here.

Breaking Bad at the Pharmacy

April 25, 2014

By Medical Discovery News

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Drug abuse is not confined to street drugs like methamphetamine, heroin, and cocaine. America is facing an epidemic of prescription drug abuse, particularly with pain relievers, depressants, and stimulants. In 2010, 7 million Americans abused prescription drugs every month.

People are able to abuse such medications by taking medicines prescribed for someone else, using them in excess, or by taking them in a way not prescribed, such as crushing and snorting pills or liquefying and injecting them to hasten the effects needed to produce a high.

Depressants, sedatives, and tranquilizers are abused by more than 2.5 million people each month. The mood-altering drug Zoloft ranks sixth on the list of abused pharmaceuticals and earned more than $500 million in sales. It is prescribed for depression, obsessive compulsive disorder, post-traumatic stress disorder, and social anxiety disorder. The 10th most abused prescription drug is Xanax (alprazolam), called Xany, blue footballs, Xanybars, or just bars on the street. Xanax had sales of almost $275 million in 2012. This drug is intended to treat anxiety or panic disorders. It is often abused because it creates what is described as a sense of wellbeing, but can be fatal when abused.

The sleeping pills Ambien and Lunesta are the fourth and seventh most abused drugs from the pharmacy, with sales of $670 and $450 million respectively in 2012. Both are used to treat difficulties falling or staying asleep but can produce hallucinations when abused. Tom Brokaw of NBC News inadvertently experienced these symptoms from Ambien while covering the last presidential campaign.    

Drugs used to treat attention deficit hyperactivity disorder (ADHD) are also widely abused, usually by students seeking a way to stay awake and intensely focus on a project or test. Other than marijuana and synthetic marijuana, Adderall is the most-used drug by high school seniors and the eighth most abused prescription drug in the country. Its sales top $400 million. Other stimulants of the central nervous system, Ritalin and Concerta, are the third and fifth most abused pharmaceuticals. Stimulants can have significant side effects like irregular heartbeat, heart failure, seizures, and behavioral changes like paranoia or hostility. 

Some of the most abused drugs are opioid analgesics used clinically as pain relievers. These drugs are involved in 75 percent of all pharmaceutical overdose deaths – more than 16,000 people a year. An estimated 5.1 million people abuse these drugs each month. This included the most abused pharmaceutical drug – Oxycontin. In 2012, sales of this drug reached about $2.5 billion. The second most abused prescription drug, Suboxone, is used as a maintenance treatment for opioid dependence. Its sales brought in almost $1.4 billion. Another opioid, Opana ER (oxymorphone), ranks ninth on the list of most abused pharmaceuticals and is used to treat severe and chronic pain. It earned $300 million in sales in 2012.

Prescription drugs like these are a double-edged sword. They do a lot of good for a lot of people, and many genuinely need them to function. New regulations that govern the use of these drugs, while annoying for people who need them, help limit some of the abusive behavior of those breaking bad.

Foxglove and High Blood Pressure

By Medical Discovery News

Sept. 8, 2012

Foxglove

Few pharmaceutical companies extract drugs from plants anymore, but a medication commonly prescribed for heart attack patients continues to come from the colorful flower foxglove. In addition, the plant may possess another life saving quality – the ability to lower blood pressure.

Foxglove, or Digitalis lantana and Digitalis purpurea, are historically important plants. The family of tall spires blooming with mostly purple flowers now has species growing all over the world, particularly along roadsides and in gardens in America. Herbalists, healers, and physicians in Ireland and Wales called it feverfew as far back as the 13th century. They used it with wine as an expectorant and an antiseptic. Native Americans brewed tea from its dried leaves to treat leg swelling caused by heart problems. In 1650, Foxglove was included in the “London Pharmacopoeia,” and then used by New England colonists by the mid-1700s.

Today, Foxglove leaves are used to make digoxin, which is commonly prescribed to treat congestive heart failure or atrial fibrillation, an irregular heartbeat. The drug increases the force of the heart’s contraction and slows its electrical impulses to regulate the rhythm.

Scientists have discovered digoxin could also treat high blood pressure.  Researchers from the University of Michigan learned a protein, RGS2, works protectively in the body to keep blood pressure in check. They found that low levels of this protein correlate with high blood pressure.

They also theorized if they could increase the body’s RGS2 levels, blood pressure would drop. Hoping an RGS2-boosting drug already existed, the team began testing thousands of medications. Not only did digoxin raise these protein levels in lab-grown cells, but it did so in mice by two to three times. Digoxin seems to work by slowing the normal degradation of the protein.

Studies on the mice showed that after seven days of being on digoxin, RGS2 levels increased in both heart and kidney tissues compared with mice not given the drug. Further tests are needed to prove that using digoxin to raise these protein levels does indeed lower blood pressure in humans. It’s also important to study long-term use of the drug.

Digoxin can be quite toxic. Since the body can’t process it quickly, the drug can build up and cause serious health problems. Symptoms of foxglove poisoning are pain in the mouth or throat followed by vomiting, diarrhea, severe headache, and irregular pulse, breathing, and heartbeat. A severe poisoning can cause convulsions and death.

Millions of Americans could benefit if further testing shows digoxin does lower blood pressure. One third of Americans lives with high blood pressure, also called hypertension. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps blood. Blood pressure that’s too high leads to coronary heart disease, heart failure, stroke, kidney failure, and many other health issues.

For a link to this story, click here.