Biomedical subjects

K V Snyder

Publications and source records attributed to K V Snyder.

3 recordsLinked to original sources

PubMed2003

Adapting the Quesant Nomad atomic force microscope for biology and patch-clamp atomic force microscopy.

The Quesant Nomad atomic force microscope (AFM) was modified to produce a reliable patch-clamp AFM for demanding biologic applications. The AFM's laser optics forms the basis of a condenser that allows simultaneous Köhler illumination and AFM imaging on an inverted optical microscope. The original AFM scan head was replaced with plastic and glass to make it biologically inert. A bevel cut in the new scan head permits clearance for patch clamp pipets. Cantilevers are attached to the scan head with a quick setting silicone rubber that is readily removable. Software was developed to (a) automate a gentle approach and set a specific feedback force, (b) provide a mouse-driven control of the X-Y position of the probe tip and recall of saved locations, and (c) measure force-distance curves over user defined paths. Additional modifications were made to minimize mechanical noise. The patch-clamp AFM achieves 600 fA (3 kHz bandwidth) and 1 A RMS noise levels (10 kHz bandwidth). The correlation of electrical and mechanical information allows signal averaging and measures sub-Angstrom, sub-millisecond electromotile responses from cells.

Cell Membrane↗

PubMed1999

A convenient electrode holder for glass pipettes to stabilize electrode potentials.

Electrophysiological techniques require stable, reversible electrodes for accurate recording. Ag/AgCl electrodes are commonly used in patch-clamp and intracellular recording pipettes, but when these electrodes are exposed to Cl--free media they are no longer reversible and may develop large, unstable offset potentials. We present here a simple electrode holder design that provides a liquid junction between the electrode solution and a KCl-filled reservoir containing the AgCl pellet. This allows an electrode solution of any composition to be used without affecting the reversibility of the electrode, and the liquid junction potentials that develop are small and well defined. Mechanical isolation of the AgCl pellet from the pipette improves long-term stability of the electrode because the AgCl coating is not scraped while changing pipettes. The response time of the holder and its wide-band noise levels are comparable to those of standard holders. For practical experiment durations, the diffusion for KCl from the reservoir down the pipette produces negligible contamination at the tip. Similarly, back diffusion of the pipette contents into the reservoir is also negligible.

Diffusion↗

PubMed1999

Anger management for adolescents: efficacy of brief group therapy.

OBJECTIVES: To investigate the efficacy of a brief, manual-based group therapy for adolescents with poor anger control. A previously developed anger management treatment package of 10 to 12 sessions was condensed to a 4-session package to be given within 2 weeks. Immediate effectiveness and the transfer of skills were investigated; anger management skills not only had to be acquired, they also had to be used in the adolescents' natural social interactions. METHOD: Fifty adolescent psychiatric inpatients were selected for high levels of anger and randomly assigned to treatment or control conditions. Pre- and posttreatment measures were administered to subjects and adults who rated the subjects' behaviors. RESULTS: Pre/post self-report measures, as well as behavior ratings by adults, indicated that the patients who went through the anger management series exhibited significantly improved skills. CONCLUSIONS: These results suggested that the intervention for adolescents was effective even though it was condensed, but it should not be further abbreviated.

Adaptation, Psychological↗