Biomedical subjects

Kenneth L Bowes

Publications and source records attributed to Kenneth L Bowes.

3 recordsLinked to original sources

PubMed2002

Microprocessor-controlled colonic peristalsis: dynamic parametric modeling in dogs.

The study aimed at completing a model of functional colonic electric stimulation and testing it for artificial recreation of peristalsis in dogs. Dynamic measurements of invoked single contractions obtained from two unconscious dogs as well as previously reported static contraction properties were utilized to suggest the optimal stimulation parameters of: (1) length of the stimulating electrodes, (2) separation between the successive electrode sets, (3) duration, and (4) phase lag between the stimuli sequentially applied to the electrode sets. The derived electrode configuration and stimulation pattern were adjusted for different anatomical dimensions and tested in distended colon full of viscous content. Forward and backward propagating peristaltic waves were invoked in two other unconscious dogs, indicating that the recreation of colonic peristalsis under microprocessor control is feasible.

Animals↗

PubMed2002

Electrical activity from colon overlaps with normal gastric electrical activity in cutaneous recordings.

The stability of EGG recordings is affected by a variety of artifacts. The aim of this study was to investigate possible overlapping of dominant frequencies in recorded cutaneous electrical activity arising simultaneously from the stomach and/or colon. Ten normal volunteers, eight posttotal colectomy patients, and four patients posttotal gastrectomy were studied. Fasting cutaneous recordings were obtained using four pediatric ECG electrodes attached to the abdominal surface. Electrical activity was recorded and digitally analyzed using custom-designed software. Spectral analysis after gastrectomy and colectomy showed persistence of power peaks in the gastric electrical activity range of frequency (2.5-3.75 cpm). In conclusion, noninvasively obtained colonic frequencies overlap EGG. This hypothesis is supported by the persistence of power peaks in the EGG range of frequency after gastrectomy and colectomy. Therefore, we conclude that contribution of electrical activity arising from the colon could substantially affect EGG recordings.

Aged↗

PubMed2002

Three-dimensional object-oriented modeling of the stomach for the purpose of microprocessor-controlled functional stimulation.

Three-dimensional (3-D) object-oriented models are needed for optimizing gastric electrical stimulation by performing virtual computer experiments. The aim of the study was to create a 3-D object-oriented electromechanical model of the stomach in vivo for the purpose of microprocessor controlled functional stimulation. The stomach was modeled using coaxial truncated conoids as objects. The strength of an external stimulating electric field generated by circumferentially implanted wire electrodes is related to artificial neurogenic and myogenic control of smooth muscle depolarization and contraction. Variation of the field strength modulates the frequency and concentration of acetylcholine release, as well as the transmembrane voltage of the muscle cells. Mechanical response of the stimulated tissue was quantified by two parametric functions of the electric field strength representing the relative contractile force and geometrical displacement of the gastric surface. Data from previously conducted canine experiments were used to test the validity of the model. The model was applied to simulate contractions with different positions, orientation and number of the circumferentially implanted stimulating electrodes. The model combined most of the existing theoretical and experimental findings concerning functional gastric stimulation and can be utilized as a flexible tool for virtual medical tests involving external high-frequency (50 Hz) neural stimulation.

Action Potentials↗