Application of miniaturized mercury column strain gauges to the study of gastric motility

On the construction, circuitry and properties of liquid metal strain gages

A quick and easy method by which reliable and accurate liquid metal strain gages (LMSG) can be manufactured for use in measuring large strains within biological tissues has been developed. The circuitry used to power the gages is also simple and allows gage voltages to be recorded without the need for instrumentation amplifiers. An added advantage is that the gage output indicates absolute gage length rather than change in gage length. Lastly, evaluation of these gages error sensitivity has shown them to be acceptable for measurement of strains of magnitudes occurring within many soft tissues.

A quarter Wheatstone bridge strain gage force transducer for recording gut motility

Quarter and half Wheatstone bridge extraluminal force transducers for recording of gastrointestinal motility are compared. Modification of the transducer to a quarter bridge is economical, simplifies construction, and improves longevity by eliminating the crossover wire which frequently short circuits. The quarter bridge transducer was found to be as accurate and sensitive as the half bridge transducer.

Motility changes in the antrum after proximal gastric vagotomy

The normal pattern of resting and post-prandial motor activity in the gastric antrum has been established by observations in 6 dogs. There was a gradual increase in the amplitude of contraction during the first 2 hours after eating; this was maintained for 3 hours and then declined. For the first 45 minutes terminal antral contraction occurred, partially retaining and triturating the gastric contents. After 45 minutes the waves became sequential, symmetrical, increased in vigour and actively pumped food into the duodenum. Vagotomy modified the mechanism of the antrum in various ways. Truncal and selective vagotomy reduced the work capability to 20 per cent of its normal value when recorded 1 month after operation. In both groups the waves were disorganized. Proximal gastric vagotomy abolished the braking mechanism and removed the initial inhibitory stimuli to antral motility. Within 1 month of operation the antrum had regained 58 per cent of its normal work capability and the contractions were well organized.