Featured Research

from universities, journals, and other organizations

Osteoporosis drugs appear to impede cell membrane repair

Date:
April 14, 2014
Source:
Medical College of Georgia at Georgia Regents University
Summary:
A class of drugs widely used to treat osteoporosis appears to impede a cell's ability to repair a protective outer membrane that helps determine what enters and exits, researchers report. The inability to quickly repair a membrane is lethal to a cell and may help explain the rare and serious side effect of jawbone destruction that can occur following dental work in patients taking these drugs, the researchers note.

This is Caroline Lewis, a sophomore at the Medical College of Georgia at Georgia Regents University.
Credit: Phil Jones

A class of drugs widely used to treat osteoporosis appears to impede a cell's ability to repair a protective outer membrane that helps determine what enters and exits, researchers report.

The inability to quickly repair a membrane is lethal to a cell and may help explain the rare and serious side effect of jawbone destruction that can occur following dental work in patients taking these drugs, said Caroline Lewis, a sophomore at the Medical College of Georgia at Georgia Regents University.

"The bottom line is it inhibits cell membrane repair in two distinct cell types," Lewis said. She is among five winners of the 2014 National Medical Students Competition of the American College of Physicians. Lewis presented her work April 12 during the college's Internal Medicine 2014 meeting in Orlando.

Working in the lab of Dr. Paul McNeil, an MCG cell biologist specializing in cell membrane repair, Lewis found that kidney epithelial cells from monkeys and muscle cells from mice both lost their ability to quickly repair their outer membrane after exposure to zoledronate, a commonly used bisphosphonate, Lewis said. Without drug exposure, cells quickly recovered from a microscope laser injury.

"That is healthy, normal repair," she said, citing a video showing the normal cell experiencing only a brief flicker of fluorescence where hit by a laser. On the other hand, zoledronate-exposed cells quickly filled with a fluorescent dye the researchers placed in the petry dish.

"All this dye coming into the cell means there is still a disruption and no repair occurred to sort of mend the fence," Lewis said. "We know these cells are dying, Basically these videos speak for themselves."

"It's a paradox," added McNeil. "On the one hand, (the drug) is given to people mainly to promote bone health, increase bone density. But in the case of a jaw that has suffered, for example, a tooth extraction, the exact opposite occurs."

He theorized cell membrane repair was contributing to destruction of the jawbone and the lining of the mouth after a 2012 report in the Journal of Proteome Research that bisphosphonates bind to cell membrane proteins vital to membrane repair. Since the severe side effect seems to occur only following dental work, McNeil made the connection.

While it's not clear whether this failure to repair is happening in other parts of the body, McNeil and Lewis note that cell membrane repair is typically a constant throughout the body.

"Pretty much every day of our life, even exercising, you are contracting your muscles, the muscle cells rub past each other and that friction causes microscopic tears in the membrane," Lewis said. "If those cells can't repair an injury, they die because they can' t maintain internal homeostasis."

Next steps include more cell studies, including those on jawbone cells, McNeil said. Kidney epithelial cells and muscle cells used in this study are routinely used in cell membrane repair research, and cell repair mechanisms tend to be consistent across cell types, even across different species, McNeil noted.

He also is pursuing the potential protective properties of vitamin E for these patients. McNeil reported in December 2011 in the journal Nature Communications that vitamin E, a powerful antioxidant found in most foods, helps repair tears in the plasma membrane. In the meantime, Lewis suggests that patients taking the drugs talk with their physicians if they have concerns. Some physicians and dentists recommend a drug holiday for these patients before having dental work.

Bisphosphonates are thought to work primarily by inhibiting bone-consuming cells called osteoclasts, which balance the activty of bone-producing osteoblasts, a balance that's lost in osteoporosis. Bisphosophonate-related osteonecrosis of the jaw, or BRON, is among a fairly long list of side effects for these drugs, including rashes swelling, upper chest pain, irregular heartbeat, and painful or swollen gums and loosening of the teeth, according to MedlinePlus Drug Information.

Bisphosphonates also are used to treat hypercalcemia, high blood levels of calcium that can result from cancer, an overactive parathyroid, and calcium supplements; as well as multiple myeloma, cancer of the plasma cells; and cancer that has spread to the bone.


Story Source:

The above story is based on materials provided by Medical College of Georgia at Georgia Regents University. Note: Materials may be edited for content and length.


Cite This Page:

Medical College of Georgia at Georgia Regents University. "Osteoporosis drugs appear to impede cell membrane repair." ScienceDaily. ScienceDaily, 14 April 2014. <www.sciencedaily.com/releases/2014/04/140414123816.htm>.
Medical College of Georgia at Georgia Regents University. (2014, April 14). Osteoporosis drugs appear to impede cell membrane repair. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2014/04/140414123816.htm
Medical College of Georgia at Georgia Regents University. "Osteoporosis drugs appear to impede cell membrane repair." ScienceDaily. www.sciencedaily.com/releases/2014/04/140414123816.htm (accessed October 21, 2014).

Share This



More Health & Medicine News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
CDC Calls for New Ebola Safety Guidelines

CDC Calls for New Ebola Safety Guidelines

AP (Oct. 20, 2014) Centers for Disease Control and Prevention Director Dr. Tom Frieden laid out new guidelines for health care workers when dealing with the deadly Ebola virus including new precautions when taking off personal protective equipment. (Oct. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins