John DiCecco

The effects of Thimerosal on the central nervous system of the pond snail lymnaea stagnalis

It is well known that certain forms of organic mercury (such as methylmercury) are neurotoxic. What has been of significant interest in recent years relates to the levels of mercury which become bioavailable after injecting vaccines which contain the ethylmercury-based preservative Thimerosal and whether those levels are significant enough to disrupt normal neuronal communication. This study does not attempt to extrapolate the observed effects of Thimerosal on neurons of the pond snail to the effects of Thimerosal on the normal neuronal development of the infant human. What we show is that there is a clear disruption of the baseline neuronal communication pattern when the extracted central nervous system is exposed to Thimerosal at 100 µM. We note that this concentration far exceeds that which is bioavailable in normal Thimerosal-preserved vaccines.

Microprocessor Based Control of Electromechanical Devices by Using Electromyogram: A "Cricket Car" Model

The Cricket Car is a remote control car that uses electromyographic (EMG) signals to drive the car. Electrodes are inserted into the legs of the common field cricket and the myoelectric signal, also known as a motor action signal, is amplified. This amplified signal is then acquired by the PIC16F88 processor. Using threshold detection and conditional logic algorithms, the PIC processor sends command signals to the circuit of a remote control car. Features such as object/collision detection, cricket stimulus, and additional signal processing algorithms have been studied and developed. The project has been incorporated into a neuroengineering course. Continuation of this project by undergraduate and graduate students will serve as the impetus for further improvements.

Experiential learning in neurophysiology for undergraduate biomedical engineering students

The undergraduate engineering curriculum generally consists of a significant amount of theory and mathematics that are deemed necessary to solve problems in the real world. For biomedical engineering undergraduates this often results in limited hands-on experiences with live tissue samples and biological experimental techniques. In the Biomedical Engineering Program at the University of Rhode Island, this issue is addressed to some extent by implementing an experiential electrophysiology laboratory. The two-semester project course exposes the students to laboratory skills in dissection, instrumentation and physiological measurements. The focus of the projects is: 1) recording of action potentials in cerebral ganglia of the pond snail (Lymnaea stagnalis), 2) measuring of contractile forces and action potentials in odontophore protractor muscles of the American channeled whelk (Busycon canaliculalum) by use of a sucrose gap apparatus. This laboratory has proven to be an effective way to provide undergraduate biomedical engineering students with invaluable experiences in neurophysiology.

A Fully Digital Implementation of Voltage, Current, and Dynamic Clamping Methodologies

Standard electrophysiology experiments utilize a technique known as voltage clamping: the surface of the cellular membrane is held constant, or clamped, which allows the researcher to study the membrane permeability and ion exchange. This process is usually performed with commercially available analog equipment. While analog circuitry provides an accurate and reliable equipment medium, it does not allow for much in the way of real-time data processing. Additionally, there is the issue of data acquisition which must be performed using an analog to digital converter (A/D). A need exists to resolve these issues in one device. The Universal Clamp, a patent pending electronic device designed and built by Dr. Jiang Wu at the University of Rhode Island, addresses this need. The Universal Clamp, however, does much more than data acquisition (DAQ) and signal processing. As the name implies, it has the capability of performing voltage clamping, current clamping, and dynamic clamping, all in one device, with the aid of a digital signal processing (DSP) chip. This functionality provides researchers greater flexibility in the types of experiments they can conduct, as well as simplifying current standard methodologies. Using the visceral ganglion from Aplysia californica, the Universal Clamp has successfully performed voltage clamping, current clamping and dynamic clamping, while simultaneously executing data acquisition and signal processing algorithms.

The Neuron Emulator: an undergraduate Biomedical Engineering design project

The Neuron Emulator was a team project by undergraduate Biomedical Engineering students in a neuroengineering course at the University of Rhode Island. It is an analog electronic apparatus that simulates the passive and active electrical properties of a neuron. Areas of application include testing of neurophysiological measurement and control instruments, and education in electrophysiology. Proposed uses of the device include working in conjunction to form a reciprocally inhibitory oscillator and to calibrate a voltage clamp amplifier.

The effects of pH on the electrophysiological properties of the CNS of lymnaea stagnalis

The central nervous system is composed of many different interacting neurons all working together to provide sensory, motor, and visceral signals to the specific organism. The environment in which those neurons operate is crucial to the survival of the organism. Some environmental factors may include pH, temperature, or the intra-and extracellular ion concentration. If any of these factors are changed in a substantial way, the electrophysiological properties of the neuron may be affected. Some of the important electrophysiological properties of the neuron include the resting potential, the action potential, and the firing rate. These properties can be measured directly using sharp microelectrode methodologies. The performed experiments consist of recording the resting potential, action potential, and firing rate from a neuron in the CNS cerebral ganglion of the Lymnaea stagnalis. This paper addresses how various levels of pH affect the electrophysiological properties of neurons in the CNS of L. stagnalis.

A Sequential Algorithm for Biological Event Detection Using Statistical Nonstationarity

High dimension complex dynamical systems, such as those found in physiological processes, are often accompanied by nonstationarity. In many cases, the nonstationarity is caused by a physiologically significant event such as the prelude to ventricular fibrillation in cardiac arrest or the change of stasis by introducing pharmaceuticals. A need exists to be able to detect and monitor this change. Most conventional attempts at addressing this problem involve segmenting the time series and evaluating the statistics of the segments. The difficulty with this approach is that the nature of the nonstationarity can be transient, such that it is bounded by two, or more, regions of stationarity. Further, vacillation between stationary and nonstationary segments may continue for a significant portion of the time series. This paper will discuss the underlying statistical justification for asserting stationarity and the use of segmentation time series analysis techniques.

A universal instrument for biological measurements, stimulation, clamping, and processing

In this paper, the design of an integrated instrument for biological experiments is presented, namely Universal Clamp. It combines the functions usually performed by separate electronic biological instruments to provide a universal solution. After simple cabling to pipette electrodes, it enables users to do membrane potential measurement, current stimulation, varieties of clamping, data acquisition, processing, and storing through a single PC-based graphic user interface.

Ginsenoside-Rg1 does not mitigate the effects of thimerosal on the central nervous system of the pond snail Lymnaea stagnalis

It is well known that certain forms of organic mercury (such as methylmercury) are neurotoxic. In a previous study, we found that the concentration levels at which Thimerosal, an ethylmercury-based preservative found in vaccines, showed neurotoxic effects after soaking for 15 minutes was 100 µM. In this study, we tested the same molar concentration of Thimerosal in the presence of the neuroprotective compound Ginsenoside Rg-1 (Panax ginseng). We found no significant mitigation of the effects of Thimerosal on neuronal function.

The effect of Gramicidin on the membrane potential of neurons in the CNS of L. stagnalis

Gramicidin is a pore-forming peptide which exhibits lethal properties against a large spectrum of cells. It forms monovalent cation-specific channel in the lipid bilayer of a cellular membrane with limited permeability to anions or polyvalent cations. Both ions and water move through the pore which is formed by the peptide backbone. We detected formation of pores induced by the dimerization of gramicidin molecules by monitoring changes in the membrane and action potentials of neurons in the central nervous system of Lymnaea stagnalis. This methodology could be used for the study of peptide interactions with neuronal cellular membranes.