A study of the combined effects of both mass transfer and phase separation kinetics on the widely used process of nonsolvent induced phase separation (NIPS) via a two-fluid model.

1 The effects of tetanic stimulation of the oculomotor nerve on transmission through the avian ciliary ganglion have been determined by use of the amplitude of the compound action potential recorded in the ciliary nerve, in the presence of hexamethonium (3001M), as a measure of synaptic efficacy. 2 Tetanic stimulation for 20 s at 30 Hz potentiated the chemical phase of the compound action potential by at least 100% of its control level. This potentiation, reflecting an increase in synaptic efficacy, decayed over two distinct time courses: firstly, a rapid decay with a time constant in the order of minutes, and secondly, a slower decay, representing a smaller potentiation, with a time constant in the order of an hour. The large increase in synaptic efficacy is attributed to post-tetanic potentiation (PTP) whereas the smaller but longer lasting increase is attributed to long-term potentiation (LTP). 3 Higher frequencies of tetanic stimulation gave increased PTP and LTP. 5 Application of the muscarinic inhibitor, atropine (2 tM), did not affect the magnitude of PTP or LTP. 6 The activator of protein kinase C, phorbol 12,13-dibutyrate (2 pM) potentiated synaptic transmission and reduced the potentiation due to PTP although it did not affect that due to LTP, but the inhibitor of this kinase, staurosporine (0.5 pM), partially blocked the appearance of LTP without affecting PTP after the tetanus.7 An inhibitor of calmodulin, W-7 (5 pM), reversibly blocked the appearance of LTP significantly after a tetanus although the size of PTP was not affected. 8 The results presented here suggest that the initiation of LTP in the ciliary ganglion is due to an influx of calcium ions into the calyciform nerve terminal during the tetanus and that the mechanism for LTP involves a calcium-calmodulin-dependent process.

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1 The effect of nitric oxide on the efficacy of synaptic transmission in the chick ciliary ganglion of post-hatched birds has been determined by use of the size of the postganglionic compound action potential resulting from chemical transmission through the ganglion as a measure of synaptic efficacy. 2 Sodium nitroprusside (100 LM) increased the synaptic efficacy by an average 26%. This is likely to be due to its ability to release nitric oxide, as potassium ferricyanide (100 gLM) did not cause a potentiation.Sodium azide (100 liM), shown in sympathetic ganglia to stimulate production of cyclic GMP, did not modulate synaptic efficacy significantly. 3 8-Br-cyclic-GMP (100 I1M) increased synaptic efficacy by an average 61%. The addition of 8-Brcyclic-AMP (100°1M) had less effect, increasing transmission by on average 46%. 4 The nitric oxide synthase blocker, NG-nitro-L-arginine methyl ester (L-NAME, 100 tM) was added prior to the tetanic stimulation of the preganglionic nerves at 30 Hz for 20 s, a procedure known to produce both post-tetanic potentiation and long-term potentiation of synaptic transmission through the ganglion. L-NAME reduced the long-term potentiation by an average of 47% but did not significantly change the post-tetanic potentiation. 5 Following the brief application of 8-Br-cyclic AMP, 8-Br-cyclic GMP and sodium nitroprusside there was an enhancement of the efficacy of synaptic transmission that persisted after the withdrawal of the drugs. The maximum increase in synaptic efficacy following the brief addition of 8-Br-cyclic GMP was 116%, sodium nitroprusside was 110% and 8-Br-cyclic AMP was 126%. 6 These results suggest that nitric oxide modulates synaptic transmission through the ganglion by acting on an endogenous guanylate cyclase that produces cyclic GMP.

Volitionally modulated electroencephalographic (EEG) waves were monitored for the purpose of controlling a hand neuroprosthesis in people with tetraplegia. The region of the EEG signal spectrum monitored was the occipital alpha wave (8-13 Hz), and volitional modulation was achieved with the opening and closing of the eyes. In a set of 13 trials evaluated, a subject with tetraplegia successfully completed ten trials undertaking stimulated grasp and release using the EEG-triggered switch. EEG signal data recorded during the 13 trials were also post-processed off-line using wavepacket analysis. Following this signal processing, the speed and reliability of the EEG-triggered switch, when operated by the subject with tetraplegia, was significantly improved (p < 0.002). Such improvements provide system performance that is likely to be acceptable to a neuroprosthesis user during activities of daily life.