Research roundup for April 11, 2017

Orphan receptor involved in opioid itching

Researchers in the UNC School of Medicine have linked an orphan receptor with opioid-induced itching.

Orphan receptors are receptors scientists know exist but aren’t sure what purpose they serve.

The Bryan Roth lab in the pharmacology department, which works to find binding molecules for orphan receptors, found the receptor MRGRPX2 is related to opioid-induced itching.

A graduate student in the Roth lab, Kate Lansu, screened around 7,000 small molecules against MRGRPX2 to see what a potential ligand might look like. From there, University California at San Francisco graduate student Joel Karpiak used a computational model to screen 3.7M molecules for a match to the receptor, finding opioids were a match.

Before finding what MRGRPX2 binds to, the researchers already knew it was a receptor on mast cells — an important component of the immune system. Lansu said itching can be caused by a release of histamines from mast cells in a process called degranulation, which also has previously been linked to opioids.

The researchers think finding this receptor could help pharmacologists create drugs to counteract opioid-induced itching along with create new medicines to increase histamine responses to boost immunity. 

Water testing in Wake County

Frank Stillo, a researcher with the Gillings School of Public Health, and Jacqueline MacDonald Gibson, a professor in the Gillings School of Public Health, embarked on a project to test the well water in 57 homes in Wake County.

With 35 percent of the North Carolina population relying on private wells, the third highest in the country, Stilo and MacDonald Gibson wanted to test for natural geologic formations, failed septic tanks, fertilizers and pesticides and landfill seepage.

They found that 65 percent of the households tested positive for at least one of three microbial contaminants. About 3,800 people in Wake County’s predominantly black neighborhoods rely on wells and septic systems.

MacDonald Gibson and Stillo used three different indicators to test for water contamination — coliform bacteria, E. coli and enterococci.

MacDonald Gibson said this issue arises in towns that grow around black communities.

“Some of these areas are doughnut holes in the middle of the city,” MacDonald Gibson said. “If there’s a fire, they have to wait for the county fire department to arrive, even if the city fire department is closer.”

They are now testing for lead in water systems in Wake County. They have tested 29 homes so far. 

Mental illness and the death penalty

Frank Baumgartner, a political science professor, and Betsy Neil, a senior majoring in psychology and political science, contributed a research article on mental illness and the death penalty to the Washington Post on April 3. Baumgartner and Neil compiled their research while working on a forthcoming book, “Deadly Justice: A Statistical Portrait of the Death Penalty”.

The United States has executed 1,448 inmates since 1976. 141 of these inmates were volunteers, meaning they chose not to appeal the death sentence. 

Baumgartner and Neil said they relied on testimony and source material revealed in trial or repeated in the news to determine whether or not an inmate had a diagnosed mental illness. They said using this criteria means they may have underestimated the number of inmates with mental illnesses. 

The research suggests the criminal justice system’s use of the death penalty applies to individuals with mental illness more than individuals without a mental illness. They discovered that 43 percent of people who received the death penalty between 2000 and 2015 also received a mental illness diagnosis at some point in their lives. 

Baumgartner and Neil found that between 2000 and 2015, 32.2 percent of death row volunteers had attempted suicide in the past. Their research also suggests that the criminal justice system disproportionately targets criminals who experienced childhood abuse and trauma with the death penalty. 

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