Knocking Out Hepatitis C

March 7, 2014

By Medical Discovery News

Hepatitis C

Good news awaits Hepatitis C patients. In the next few years, new drugs that specifically target the Hepatitis C virus, curing a person more quickly without the severe side effects, will become available. Some physicians and patients are even opting to wait for these new drugs rather than endure the current therapy.

Today, this viral infection is most often acquired by drug users sharing needles. The Hepatitis C virus can cause a mild illness lasting a few weeks but in some people it can cause a serious lifelong illness. One major problem is that many people are unaware that they are infected until they have symptoms of liver damage. It is the leading cause of cirrhosis and liver cancer and the most common reason for liver transplantation in the United States.

An estimated three to four million Americans are infected, and deaths from Hepatitis C are expected to rise in the future as those unaware of their infections begin to have symptoms. There is no vaccine and the current drug regimens can cure about 70 percent of infected people but the serious side effects include anemia, insomnia, depression, fever, and severe rashes.

Hepatitis C is most commonly treated with a combination of interferon and ribavirin for 24 to 48 weeks. However, because of their side effects and the fact that the drugs do not work for everyone, drug companies have been working hard to develop new treatments.

These new drugs are predicted to wipe out Hepatitis C infections with one pill per day for as little as eight weeks, without severe side effects. The only downside is their predicted costs range from $60,000 to more than $100,000 for a course of treatment. The new drugs, much like those that are used to treat HIV infection, target enzymes the Hepatitis C virus requires to reproduce.  However, the Hepatitis C virus does not make its genetic information a permanent part of a cell’s genome like HIV does, so it can be eliminated, therefore curing the person. If the virus is eliminated the liver can heal itself to some extent, but people cured of Hepatitis C may still be at higher risk for liver cancer.

One of these new drugs, called sofosbuvir by Gilead Sciences, inhibits the enzyme that copies the virus’s genetic information, therefore blocking virus reproduction. The effectiveness of the drug depends on the type of Hepatitis virus. The majority of Hepatitis C patients in the U.S. would require the addition of interferon for 12 weeks. Gilead has a second drug nearly ready called ledipasvir, which in combination with ribavirin could eliminate the need for interferon, the source of the worst of the side effects of current treatments.

Several other companies are racing to introduce additional medications to treat Hepatitis C. Having tolerable therapies available will encourage people to get tested and treated earlier for Hepatitis C, before liver damage begins. This is a huge benefit to public health that will substantially reduce the need for liver transplants and the number of deaths from liver failure and liver cancer.

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An Itchy Situation

Nov. 1, 2013

By Medical Discovery News

Anyone ever bitten by a mosquito can attest to its itchy consequences. New research has discovered just how our bodies detect and process itching, leading to a better understanding of our reaction to itching and hopefully better treatments for it.

The clinical term for an itch is pruritus, and at least 16 percent of people experience an itch that just doesn’t go away. The most common dermatological complaint, long-term itching can be caused by chronic renal disease, cirrhosis, some cancers, multiple sclerosis, diabetes, shingles, allergic reactions, drug reactions, and pregnancy.

Prolonged itching and scratching can increase the intensity of the itch, possibly leading to neurodermatitis, a condition in which a frequently scratched area of skin becomes thick and leathery. The patches can be raw, red, or darker than the rest of the skin. Persistent scratching can also lead to a bacterial skin infection, permanent scars, or changes in skin color. The super strong pain reliever morphine can cause such a severe whole-body itch that some patients choose to forgo it and live with the pain.

Sensory neurons called TRPV1 cells detect itchy substances on skin. TRPV1 cells have long nerve fibers that extend into skin, muscle, and other tissues to help monitor conditions. It has not been clear how these neurons sort through different sensations like pain and temperature and route the signal along the proper pathway to the appropriate area of the brain for perception.

New research has revealed a small group of those neurons produce a substance called natriuretic polypeptide b (Nppb), a hormone known to be involved in regulating the heart. Surprisingly, when Nppb is produced by TRPV1 cells it acts as a neurotransmitter, a chemical messenger secreted by neurons to carry, boost, and control signals between neurons and other cells.

When scientists genetically modified mice to eliminate Nppb, they did not itch. Nppb binds to a specific receptor called Npra on particular nerves in the spinal column. When those cells were eliminated in mice, again, they did not itch. Interestingly, removing these cells did not impact other sensory sensations such as temperature, pain, and touch.

A similar transmission presumably exists in humans, but that has not yet been determined. Knowing which molecules and cells are involved will help scientists study how humans perceive itch signals. Before these findings, scientists thought a molecule called gastrin releasing peptide was responsible for transmitting the itch signal from nerves, and that itching was a low level form of pain.

Understanding the itch signaling pathway offers the opportunity to create drugs that specifically block that signal and alleviate unpleasant and chronic itching with fewer side effects.

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