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B Pomeranz

Publications and source records attributed to B Pomeranz.

At least 37 records · Page 2Linked to original sources
PubMed1985

Assessment of autonomic function in humans by heart rate spectral analysis.

Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.

Adult↗
PubMed1984

Long latency spinal cord dorsum potential; suppression by intrathecal morphine and enkephalin analog.

We have developed a new method which combines intrathecal recordings of spinal cord dorsum potentials (CDPs) with application of drugs to the spinal cord via an intrathecal catheter. With this technique we have discovered a late component (LC) in the CDP which has not been previously described. The LC is evoked by high intensity electrical stimulation of the rat tail. Whereas previous reports describe early components in the CDP evoked by low intensity A-fiber stimulation, ours is the first to describe a late evoked potential implicating C-fiber activation of the cord. Moreover, we show that the LC is blocked by intrathecal application of morphine sulphate or D-Ala-Met-enkephalinamide in a naloxone reversible manner. We postulate that this LC represents, at least in part, the spinal cord evoked response to C-polymodal nociceptive afferent inputs.

Analgesics↗
PubMed1984

Effect of applied electrical fields on sprouting of intact saphenous nerve in adult rat.

Saphenous nerve sprouting was measured behaviorally and histologically after chronic sciatic denervation in the adult rat. The effect of electrical stimulation (either weak DC fields, or stronger AC fields) on the rate of sprouting of the intact saphenous was studied. Sprouting was enhanced by DC fields (1 microA) if the cathode was placed distal to the growth tips, but was unaffected by anode stimulation. Sprouting was also enhanced by AC fields (1000 microA per pulse) given at 20 Hz and 0.1 ms duration. In the discussion we postulate that separate mechanisms might mediate the AC and DC results. The DC effects are the first demonstration in mammals of results previously observed in lower vertebrates.

Animals↗
PubMed1984

Spread of saphenous somatotopic projection map in spinal cord and hypersensitivity of the foot after chronic sciatic denervation in adult rat.

The left sciatic nerve was cut and ligated in adult rats (chronic denervation). Twenty-one days later the right sciatic nerve was cut and ligated (acute denervation). The somatotopic maps of the surviving intact saphenous nerves (left and right) were compared on day 21 by recording from single interneurons in the dorsal horn of the spinal cord. On the acute side saphenous mediated natural responses were observed only as far caudally as L3, while no natural responses were found in L4 and 5 (this silent zone in L4 and 5 had previously been sciatic territory). In contrast, after chronic sciatic denervation, L4 and L5 were not silent to natural stimulation as the saphenous natural responses had spread into the sciatic territory. Saphenous inputs always won the sciatic territory in L4 and L5 over competing thigh afferents after chronic sciatic denervation. Electrical stimulation of the saphenous nerve on the acute side produced unit responses all the way down to S1 (with no silent areas in L4 and 5). These electrically evoked unit responses in L4 to S1 of the acute side were called 'long range' pathways. There were no differences in 'long range' electrical responses in the acutely and chronically denervated cord. The caudal boundary for electrically evoked saphenous responses was S1 on both sides of the cord, and post stimulus histograms of unit responses were not statistically different on the two sides. Thus after chronic sciatic denervation natural responses mediated by saphenous spread caudally into sciatic territory, but electrically evoked responses did not change. Behaviorally, there was the expected spread of saphenous mediated responses from the medial toe and foot to more lateral regions after chronic sciatic denervation. Unexpectedly, there was an increase in sensitivity (hyperalgesia) of the medial toe and foot. We postulate that this increased sensitivity might be mediated by the spread of saphenous projections into L4 and L5 of the cord after chronic sciatic denervation. Perhaps post traumatic neuralgia in humans could be due to increased number of spinal cord cells responding to stimulation of the receptive field of the surviving nerve.

Animals↗
PubMed1982

Chronic peripheral nerve injuries alter the somatotopic organization of the cuneate nucleus in kittens.

The effect of chronic peripheral nerve injuries on the somatotopic organization of the cuneate nucleus was examined in kittens, using electrophysiological techniques. In normal kittens, most cells in the dorsal part of the nucleus possessed small receptive fields on the ipsilateral front paw. Several weeks after paw denervation in young kittens, however, many cells in the corresponding dorsal part of the nucleus responded to tactile stimulation of the wrist, forearm, or trunk. Consistent with this change in receptive fields, the neurons in the dorsal part of the nucleus were more responsive to electrical stimulation of the medial cutaneous nerve, which innervates part of the forearm, in kittens after paw denervation than in control kittens. These somatotopic changes were not an artifact of severe atrophy of the dorsal part of the nucleus. This experiment confirms that after chronic peripheral nerve injuries, central somatosensory neurons can begin to respond to ascending afferent volleys originating from other undamaged peripheral axons, which were previously incapable of exciting the cells. Moreover, this change in functional connectivity is evident at the first synapse central to the injury site.

Animals↗
PubMed1981

Monoaminergic mechanism of electroacupuncture analgesia.

We studied the effects of systemic injections of monoamine depletors, enhancers or receptor blockers on electroacupuncture analgesia (EAA) in mice. The following results emerged. (i) EAA is reduced by depletors of monoamines (tetrabenazine, TBZ depletes all monoamines; para-chlorophenylalanine, PCPA depletes serotonin; alpha-methyl-para-tyrosine, AMPT depletes catecholamines). However, depletion of noradrenaline and increase of serotonin by disulfiram enhances EAA. (ii) Replacement of depleted monoamines after TBZ treatment by their precursors (5-HTP or L-DOPA) restores EAA. (iii) EAA is enhanced by potentiating serotonin and dopamine by probenecid. EAA is also enhanced by the administration of monoamine precursors (L-DOPA for dopamine, 5-HTP for serotonin). The dopamine receptor stimulator, apomorphine, reduces EAA. (iv) EAA is also reduced by receptor blockade of catecholamines (by haloperidol), or blockade of noradrenaline (by yohimbine) or serotonin (by cinanserin). However, blockade of dopamine by pimozide has no significant effect on EAA. There are two main conclusions: (i) EAA results are similar to those previously reported for SPA for all drugs except apomorphine and pimozide; and (ii) EAA shows consistent results only with manipulations of serotonin: the data indicating that EAA (at 200 Hz) is mediated by serotonin. Since previous studies show that raphe or DLF (dorsolateral fasciculus) lesions abolish EAA, we postulate that descending axons from raphe release serotonin to inhibit trigeminal or spinal cord nociception during EAA.

5-Hydroxytryptophan↗
PubMed1980

Electroacupuncture treatment of morphine-dependent mice reduces signs of withdrawal, without showing cross-tolerance.

Morphine pellets (75 mg morphine base per pellet) were implanted subcutaneously in mice (B6AF1/J) and were surgically removed after 3 or 8 days. During morphine abstinence (7 h after pellet removal), the mice were treated with electroacupuncture (EA). The results indicate that EA analgesia shows no cross-tolerance to morphine. Additionally, EA reduced withdrawal behaviour (jumping) in 50% of the mice during morphine abstinence.

Acupuncture Therapy↗
PubMed1980

Electroacupuncture elevates blood cortisol levels in naive horses; sham treatment has no effect.

It was hypothesized that electroacupuncture releases beta-endorphin and ACTH from the pituitary. Since ACTH induces the release of cortisol from the adrenal glands, blood cortisol level should be enhanced by electroacupuncture. The present result shows that the blood cortisol levels of horses are significantly increased after 30 min of electroacupuncture treatment while the sham treatment (control) shows an insignificant effect.

Acupuncture Therapy↗
PubMed1979

Effects of enkephalin analogue and naloxone on cat spinal cord dorsal root potentials.

A systemically active enkephalin analogue, FK33824, given intravenously depressed dorsal root potentials in cat spinal cord. The negative DR V and positive DR VI, measured by computer, were both decreased; this effect was reversed by small doses of intravenous naloxone. Naloxone, given alone, with no previous analogue produced no changes in dorsal root potentials suggesting the absence of a basal enkephalin tone. A second injection of FK33824 was much less effective that the first dose. The results were discussed in relation to presynaptic mechanisms for analgesia: we proposed that FK33824 causes presynaptic inhibition by modulation rather than by depolarization of primary afferent fibers.

Animals↗
PubMed1979

Chronic paw denervation causes an age-dependent appearance of novel responses from forearm in "paw cortex" of kittens and adult cats.

1. In normal kittens and cats, cells in a region of primary somatosensory cortex (SI) responded exclusively to input from the contralateral front paw; we called this area paw cortex (PC). A neighboring region of SI responded to input from the contralateral forearm above the wrist; we called this area forearm cortex (FC). The centers of PC and FC were about 4 mm apart. 2. In kittens several weeks after transection of the nerves to the front paw, the following changes were observed in PC: a) 52% of PC cells had receptive fields on the forearm; normally, PC cells responded to natural stimulation only of the front paw; b) many cells in PC (58%) responded to electrical stimulation of the medial cutaneous nerve from the forearm; normally, very few PC cells (9%) responded to this nerve; c) there was a 370% increase in the median amplitude of medial cutaneous-evoked potentials in PC; d) in contrast to these enhanced inputs, PC responses to ulnar nerve stimulation decreased significantly. 3. In adult cats, paw denervation initiated a similar process as in kittens, but with less marked somatotopic changes. 4. In both kittens and adults, FC was unaffected by the nerve injuries. 5. We conclude that a chronic peripheral nerve injury can produce extensive changes in SI cortex somatotopic organization; the nature of the effect is age dependent.

Age Factors↗