Electrical interfacing of neurotransmitter receptor and field effect transistor

The interfacing of a ligand-gated ion channel to a transistor is studied. It relies on the transduction of ion current to a voltage in a cell-transistor junction. For the first time, a genetically modified cell is used without external driving voltage as applied by a patch-pipette. Using a core-coat conductor model, we show that an autonomous dynamics gives rise to a signal if a driving voltage is provided by potassium channels, and if current compensation is avoided by an inhomogeneous activation of channels. In a proof-of-principle experiment, we transfect HEK293 cells with the serotonin receptor 5-HT3A and the potassium channel Kv1.3. The interfacing is characterized under voltage-clamp with a negative transistor signal for activated 5-HT3A and a positive signal for activated Kv1.3. Without patch-pipette, a biphasic transient is induced by serotonin. The positive wave is assigned to 5-HT3A receptors in the free membrane that drive a potassium outward current through the adherent membrane. The negative wave is attributed to 5-HT3A receptors in the adherent membrane that are activated with a delay due to serotonin diffusion. The implementation of a receptor-cell-transistor device is a fundamental step in the development of biosensors that combine high specificity and universal microelectronic readout.

Vaginal operative delivery in Germany: a national survey about experience and self-reported competency

Background: To determine German obstetricians' self-perceived experience with vacuum and forceps deliveries.Patients and methods: Using a web-based survey, German obstetricians were invited to participate in a survey. This survey was approved by the German society of obstetrics and gynecology.Results: Surveys of 635 obstetricians were received. All obstetricians reported performing significantly less forceps than vacuum deliveries. Almost all obstetricians want to perform more delivery, which indicates the willingness to learn both. More obstetricians felt confident to perform vacuum than forceps. In a similar obstetrical indication, most of the obstetricians would prefer to perform a vacuum assisted delivery. The majority of the obstetricians wished to receive more training in vaginal operative deliveries.Conclusion: Most of the German obstetricians prefer to use vacuum-assisted vaginal deliveries and feel less confident to perform forceps deliveries. Standardized training to improve the quality of care is recommended.