The relationship between the gustatory input and motor output in the glossopharyngeo-hypoglossal reflex was analyzed on the basis of neuronal activities in the solitary tract and hypoglossal motor nuclei of bullfrogs. Concentration-response relations for NaCI, quinine and acetic acid, obtained from the glossopharyngeal (IXth) nerve and simultaneously recorded from the hypoglossal (XIIth) nerve, were expressed relative to the response of each nerve to 1 M NaCI. Compared with a relatively small amount of the afferent input for acid, the reflex motor output was much larger in the relative value. A similarly high output relation was obtained for warmed saline but not for quinine and cooled saline. Although the responsiveness of the nucleus tractus solitarius neurons to 1 M NaCI and 1 mM quinine was not significantly different from that of the hypoglossal motoneurons, responses to 10 mM acetic acid were greater in the latter neurons than in the former by a factor of about 5.2. These phenomena were consistent with those in the peripheral nerves. The solitary tract neurons responsive to NaCI, quinine and acid showed both the phasic and tonic components of discharges. According to classification by a transiency index, the discharge mode became more phasic for the hypoglossal motoneurons responsive to NaCI and quinine, but more tonic for those responsive to acid. The above-mentioned chemoreflex is thus regulated by the intrinsic neural network which sends signals to the XIIth nerve after modifying not only the amount but also the temporal pattern of gustatory nerve signals for a particular taste.

The function of 9 St. Jude prosthetic mitral valves in 8 children was evaluated by continuous wave Doppler (CWD) echocardiography 28±22 months after implantation. All valves were apparently functioning normally on clinical examination. Peak flow velocity, mean flow velocity, pressure half‐time and mean pressure gradient were determined from the transmitral flow velocity curve by CWD echocardiography. For comparison, the same parameters were examined in 15 normal children and 14 adults who had undergone mitral valve replacement. All measured values were greater in adults and children who had undergone valve replacement than in normal children. There were no differences in any parameter in adults or children in whom prostheses 25 mm or larger had been implanted. Although 3 children in whom prostheses 23 mm or smaller had been implanted had greater values for each parameter than those who received 25 mm or larger prostheses, there were no symptoms or signs of mitral stenosis. These data may be useful as guidelines for normal Doppler characteristics for St. Jude mitral valves in children. In an asymptomatic child whose prosthetic valve developed obstruction by granulation tissue overgrowth, each parameter significantly worsened as the heart rate increased. The changes in these parameters in 2 normally functioning St. Jude valves during atrial pacing were insignificant. The fluctuation of Doppler characteristics with changes in heart rate is useful for differentiating normally functioning prosthetic valves from impending stenosis.