Substrate properties of analogs of myo-inositol

The hydrolysis of the minor cell membrane lipid phosphatidylinositol-4,5-bisphosphate mediates the action of many growth factors and hormones. As an approach to the development of specific inhibitors of this process, we have synthesized a series of analogs of myo-inositol and have evaluated their ability to serve as substrates for phosphatidylinositol synthetase. Modification at the 2-, 3-, or 4-positions produced compounds unable to serve as substrates, but several 5-modified analogs retained activity as substrates of phosphatidylinositol synthetase. The product formed from 5-deoxy-5-fluoro-myo-[3H]inositol by phatidylinositol synthetase was hydrolyzed by phospholipase D and gave 5-deoxy-5-fluoro-myo-inositol as the radiolabeled product. Two analogs, 5-deoxy-myo-inositol and 5-deoxy-5-fluoro-myo-inositol, were shown to permeate L1210 leukemia cells and be incorporated into cellular phospholipid. Analysis of the radiolabeled lipids formed on incubation of L1210 cells with 5-deoxy-5-fluoro-myo-[3H]inositol indicated that the fradulent lipid formed was further phosphorylated to the monophosphate but not to the diphosphate form.

Antidromic mapping of descending axons of respiratory bulbospinal neurons in the nucleus tractus solitarius of the rabbit

Antidromic mapping of the descending axons of the respiratory bulbospinal neurons in the region of the nucleus tractus solitarius (NTS) was performed on rabbits anesthetized with urethane. Among 177 units tested, 29 out of 87 inspiratory (I), 27 out of 84 expiratory (E) and 2 out of 6 phase-spanning units were identified as bulbospinal. A prominent feature of the bulbospinal pathway from the NTS in the rabbit is the abundance of ipsilateral descending axons. The axons rising from one side are situated in the ventrolateral and ventral funiculi of both sides. The axonal conduction velocities are about 25-35 m/s. Both I and E bulbospinal neurons can be divided into R alpha and R beta types according to 'no I inflation' and 'maintained E inflation' tests.

Respiration related neurons in the region of the nucleus tractus solitarius of the rabbit

Systematic mapping of respiration-related units (RRUs) in the region of the nucleus tractus solitarius (NTS) was performed on rabbits anesthetized with urethane. Of 523 RRUs 295 (56%) were inspiratory (I), 130 (25%) expiratory (E) and 98 (19%) phase-spanning (PS). Such a large number of E and PS RRUs in NTS have not been reported in the cat. Six out of 16 I RRUs 6 of 13 E RRUs, and 1 of 3 PS RRUs had projections to contralateral cervical spinal cord. The 'no I inflation' test was conducted on 76 I and 38 E RRUs, of which 29 I RRUs were identified as I alpha and 31 as I beta. Thirteen E RRUs were inhibited and 6 facilitated by preceding lung inflation. Almost all types of respiratory neurons so far reported from different nuclei of cat's brainstem have been located in the NTS region of the rabbit.

The role of the human caudate nucleus in acupuncture analgesia

The role of the caudate nucleus in acupuncture analgesia was studied in 17 patients receiving caudate stimulation through chronic implanted electrodes to relieve intractable pain caused by late malignancy. Electrical stimulation of the head of the caudate nucleus provided relief from intractable pain in all 17 patients. The pain and pain tolerance threshold were elevated, the alteration in skin galvanic activity, respiratory movement and fingertip plethysmography elicited by a given painful stimulus were depressed. The analgesia required a period of induction and persisted for some time after cessation of stimulation; it showed no obvious segmental topography. These characteristics are similar to those observed in acupuncture analgesia. The effect of caudate stimulation was similar to that of electric needling in depressing the late component of the somatosensory evoked potentials (SEPs) recorded over the scalp and from the centrum medianum of the thalamus. Evoked potentials could be recorded from the caudate nucleus when an acupuncture point was electrically stimulated. The evoked potential record was a complex wave of positive and negative components, the peak latencies of main components being 100-180 msec for positive wave and 148-332 msec for negative wave components. The present study supports the supposition that the caudate nucleus may play a role in acupuncture analgesia. The possibility that the effect of caudate stimulation is brought on by inhibiting the activity of the medial thalamus is discussed.