Bioresponsive Hydrogel Can Release Proteins on Cue

Researchers at Penn State have developed a DNA-laced hydrogel that mimics biological systems by releasing a proteins in response to a chemical signal, a technology which could be useful for drug delivery. The system has potential for on-demand release of therapeutic proteins, also known as biologics, to treat a variety of conditions.

Hydrogels are composed of a network of polymer chains infused with water. They have attracted a lot of attention as they can be biocompatible and are suitable for implantation in the body due to their unique biological and physical properties. A research group at Penn State is developing a ‘smart’ hydrogel that mimics the way biological systems can respond to chemical signals, such as the way in which glucose can stimulate the release of insulin.

The hydrogel is made from a polymer called polyethylene glycol, but is also laced with two types of DNA, including aptamers, which are short strands of DNA, and double-stranded helical DNA. The aptamers bind to the therapeutic protein encased in the gel, while the helical DNA is reactive to an external chemical signal.

In this example, a signal such as glucose stimulates the DNA helices in the gel to unwind. One DNA strand binds to the glucose, while the other causes the aptamer to release the insulin into the environment surrounding the gel. The system can be customized to release a variety of therapeutic proteins in response to a variety of chemical signals.

“With rational design, this biomimetic hydrogel system constitutes a general platform for controlling the output of signaling proteins for versatile potential applications such as drug delivery, cell regulation, molecular sensing and regenerative medicine,” in a statement said Yong Wang, a researcher involved in the study.

Study in Chemical Science: Displacement and hybridization reactions in aptamer-functionalized hydrogels for biomimetic protein release and signal transduction…

Via: Penn State…

When Is A Physician Too Old To Practice?

There are about a quarter of a million physicians who are currently 65 or older and in practice. This represents about a quarter of those currently practicing. Unlike other professions like federal judges, FBI employees, and nuclear materials couriers, there is no mandatory retirement age for doctors. Although not forced to retire, commercial pilots are more closely monitored after they turn 65. But our profession has not really done a very good job of policing itself. It relies on voluntary action to identify struggling colleagues, who are generally reluctant to report a partner.

We are all living longer, and physicians are no exception. This means that many continue to practice well beyond the “customary” retirement age. What exactly happens to us? One study gave a quick cognitive test to a group of physicians and compared them to non-physician controls. Here are the results:

Ages ranged from 30-80 years. Note that the physician scores were consistently higher than the controls for all age groups, but declined significantly with age just like the controls. The big problem is that individuals have difficult recognizing (or accepting) their own cognitive decline.

The American College of Surgeons (ACS) assembled a workgroup to address this issue. They recommended that surgeons undergo voluntary, confidential testing of their baseline vision and physical examination starting at age 65-70, with regular re-evaluation afterwards. So far, only 3 or the more than 5,000 hospitals in the US do this. Canada has a mandatory age of 70 for commencing regular peer evaluations of competence. Obviously, the US does not.

There are really two components at play: wellness (which includes cognition) and competence. The problem is the neither correlates well with chronological age, but rather physiologic age. And the latter is impossible to quantify.

So what do we do? This is a problem that can’t be ignored from a patient safety standpoint. But it does not readily lend itself to simple pronouncements of a mandatory retirement age. There are many physicians who can and do provide excellent service to their patients well past the customary retirement age. They are able to apply a lifetime of lessons learned that their younger colleagues simply do not have.

We need uniform adoption of mandatory, not voluntary, testing of wellness and competence. Individual hospitals need to heed the recommendations of national organizations like the ACS to implement these mandatory programs to ensure fairness and avoid the specter of age discrimination lawsuits.

I’m no spring chicken anymore, and I think about this every time I find myself searching for the name of that weird retractor I need. How old is too old? What do you think?

Reference: The Aging Physician and the Medical Profession. JAMA Surgery 152(10):967-971, 2017.


CRACKCAST E121 – Anemia, Polycythemia, and White Blood Cell Disorders

This 121st episode of CRACKCast covers Rosen’s 9th edition, Chapter 112 and 113, Anemia, Polycythemia, and White Blood Cell Disorders. These blood disorders are numerous and this episode attempts to break their classification and approach down in a systematic manner. Shownotes – PDF Here [1] Outline the important aspects of the history and physical for clinically severe and non-emergent anemia Refer to boxes 112.2 and 112.3 for the important aspects of the history and ...

The post CRACKCAST E121 – Anemia, Polycythemia, and White Blood Cell Disorders appeared first on CanadiEM and was written by Nathan Stefani.