Research Roundup |
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October 13, 2015, Volume 62, No. 09 |
Twitter Behavior Can Predict Users’ Income Level, New Penn Research Shows
Penn Dental Medicine Study Produces Low-cost, Shelf-stable Drug in Lettuce
Twitter Behavior Can Predict Users’ Income Level, New Penn Research Shows
The words people use on social media can reveal hidden meaning to those who know where to look.
Linguists have long been fascinated by this notion, connecting a person’s words to age, gender or even socioeconomic status. Now computer scientists from the University of Pennsylvania and elsewhere have gone a step further, linking the online behavior of more than 5,000 Twitter users to their income bracket. They published their results in the journal PLOS ONE.
Daniel Preotiuc-Pietro, a post-doctoral researcher in Penn’s Positive Psychology Center in the School of Arts & Sciences, led the research, collaborating with Svitlana Volkova of Johns Hopkins University, Vasileios Lampos and Nikolaos Aletras of University College London and Yoram Bachrach of Microsoft Research.
The team took an opposite approach to what psychologists and linguists have historically done: rather than asking direct questions, the scientists looked at participants’ social media posts, often full of intimate details despite the lack of privacy these outlets afford. Researchers from Penn’s World Well-Being Project, of which Dr. Preotiuc-Pietro is a part, are curious about social media as a research tool that can support or even replace expensive, limited and potentially biased surveying.
For this experiment, the researchers started by looking at Twitter users’ self-described occupations.
In the United Kingdom, a job code system sorts occupation into nine classes. Using that hierarchy, the researchers determined average income for each code, then sought a representative sampling from each. After manually removing ambiguous profiles—for example, listings referencing the film Coal Miner’s Daughter grouped as “coal miner” for profession—the team ended up with 5,191 Twitter users and more than 10 million tweets to analyze.
“It’s the largest dataset of its kind for this type of research,” said Dr. Preotiuc-Pietro. “The dataset enabled us to do something no one has really done before.”
From there, they created a statistical natural language processing algorithm that pulled in words that people in each code class use distinctly. Most people tend to use the same or similar words, so the algorithm’s job was to “understand” which were most predictive for each class. Humans analyzed these groupings and assigned them qualitative signifiers.
Some of the results validated what’s already known, for instance, that a person’s words can reveal age and gender, and that these are tied to income. But Dr. Preotiuc-Pietro said there were also some surprises; for example, those who earn more tend to express more fear and anger on Twitter. Perceived optimists have a lower mean income. Text from those in lower income brackets includes more swear words, whereas those in higher brackets more frequently discuss politics, corporations and the nonprofit world.
Dr. Aletras noted an overall picture that emerged about Twitter use.
“Lower-income users or those of a lower socioeconomic status use Twitter more as a communication means among themselves,” he said. “High-income people use it more to disseminate news, and they use it more professionally than personally.”
Strong correlations like these, between what the researchers describe as online expression and offline demographics—for example, occupation grouping or income level—also proved intriguing, Dr. Lampos added. “This work attempts to highlight some of the potential causal factors in these relationships.”
Such findings will act as a baseline for future work, some of which will investigate how perceptions about user income align with reality.
Penn Dental Medicine Study Produces Low-cost, Shelf-stable Drug in Lettuce
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(above) Henry Daniell |
Biopharmaceuticals, or drugs that are based on whole proteins, are expensive to make and require refrigeration to store. Insulin, for example, is unaffordable and inaccessible to most of the global population.
At the University of Pennsylvania School of Dental Medicine, Henry Daniell and colleagues have been working to overcome these obstacles by using a plant-based system to make shelf-stable drugs. In a study published in the journal Biomaterials, the researchers confirmed the viability of their method for FDA approval and human use, producing an effective drug that promotes tolerance to clotting factors, which could be taken by hemophilia patients, using freeze-dried lettuce leaves.
This is the first time a group has shown the commercial viability of producing a low-cost drug made from whole plants. “This is a milestone in our field, to make a fully functional drug in plants, produce it at a large scale and in quantities sufficient for human clinical trials,” Dr. Daniell said.
Dr. Daniell, professor and interim chair in Penn Dental Medicine’s department of biochemistry, is senior author on the study. Collaborators from the University of Florida, led by Roland Herzog, conducted animal studies. Fraunhofer USA’s Steve Streatfield facilitated large-scale production of lettuce in the company’s FDA-compliant facility.
The study builds on previous work by Dr. Daniell’s group demonstrating an ability to use genetically modified plants to introduce a protein into the body that would teach the immune system to tolerate clotting factors that are given as a treatment for hemophilia.
Normally, 20 to 30 percent of people who get infusions of clotting factor develop antibodies against them that interfere with treatment. The earlier study, published in the journal Blood, successfully stopped and even reversed the production of these clotting factor inhibitors by feeding the plant-based drug to mice with hemophilia A. That study used a tobacco plant platform to “grow” the drug. To take this approach into humans, however, Dr. Daniell’s team knew they needed to use a different plant species.
They launched work with lettuce, which required using a completely different genetic vector to introduce the therapeutic gene into the plant cell’s DNA, as the tobacco construct would not work in a different species. After identifying a compatible vector, they used a similar protocol to their previous work, bombarding lettuce leaves with a fusion of the therapeutic protein, coagulation factor IX, or FIX, with cholera toxin B subunit, which allows the protein to reach the immune system. They then evaluated the resulting plants for those that took it up and then grew those plants to maturity.
The next step was to ensure that the drug would be shelf stable. To do that, they freeze dried the plant material, ground it and analyzed the resulting fine powder for expression levels of the fusion protein to determine the appropriate dose and to evaluate its efficacy.
Similar to their previous experiments, Dr. Herzog’s lab fed hemophilia B mice with a suspension of plant cell containing clotting factor IX twice a week for eight weeks and then gave them the same clotting factor that human hemophilia patients take to encourage blood clotting. As before, their product was a success: mice given the drug had greatly suppressed inhibitor formation compared to untreated animals, even when various doses of the drug were tested.
“One of the key findings of our study was that we found our drug was efficacious across at least a 10-fold dose range,” Dr. Daniell said.
Such flexibility is important for translation of the drug to humans, as there may be individual variations in how a drug is metabolized in the gut as plant cells are broken down by commensal bacteria.
In the work, the researchers used two different growing systems. One was in the greenhouse on Penn’s Pennovation Works campus, a high-tech facility that grows the plant in soil and uses natural light. The second was the Fraunhofer USA facility, which more closely replicates how a commercial pharmaceutical production facility would run, using a hydroponic system and artificial lighting.
“Despite the fact that plants in the greenhouse were receiving 50 times more light, the Fraunhofer yield was quite close to ours and quite good,” Dr. Daniell said. “In 1,000 square feet, they could produce 36,000 doses.”
A hydroponic system could also easily be scaled up by adding racks and thus using vertical space, which a traditional greenhouse could not do. The researchers were able to harvest a new batch of pharmaceutical-containing lettuce every four to six weeks.
With this study, which confirms the viability of a plant-based biopharmaceutical production on a commercial scale, the researchers have eliminated several expensive obstacles that hamper the development of affordable traditional protein drugs. The method requires no fermenter, no purification to ensure sterility and no cold chain to keep the drug refrigerated. In addition, the researchers found that their capsules remained potent and effective for two years, ensuring the product is shelf-stable and patients could theoretically take the drug from home.
“Not only did we show a truly translational result for helping hemophilia patients,” Dr. Daniell said, “but this also changes the way we think about delivering protein-based drugs to human patients.
“Current treatments for inhibitor formation in hemophiliacs cost almost a million dollars and are not affordable for a significant segment of the patient population,” he said, “but the new drug is dramatically cheaper and may offer even a better solution for treating hemophilia patients. Most important, developing a low cost platform for protein drug delivery will make these drugs affordable for a large majority of the global population.”
Additional authors on the study included Aditya Kamesh, also from Penn Dental Medicine; co-lead author Liqing Zhu, Alexandra Sherman, Xiaomei Wang and Roland W. Herzog from the University of Florida; and Joey H. Norikane and Stephen J. Streatfield from Fraunhofer USA.
Large-scale production was supported by Novo Nordisk and basic science was supported by two NIH grants. A short-term exchange student fellowship to Dr. Zhu was provided by the National Nature Science Foundation of China.
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