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Biomedical subjects

B Pomeranz

Publications and source records attributed to B Pomeranz.

At least 19 recordsLinked to original sources
PubMed2001

Dalteparin vs. enoxaparin as prophylaxis for deep-vein thrombosis after total hip or knee arthroplasty: a retrospective analysis.

OBJECTIVE: To assess the clinical and economic consequences of a formulary switch from enoxaparin to dalteparin as first-line prophylaxis for deep-vein thrombosis in patients undergoing inpatient rehabilitation after total hip arthroplasty or total knee arthroplasty. DESIGN: Retrospective cohort study. RESULTS: There were 461 patients eligible for the study. The age-adjusted risk of a deep-vein thrombosis event confirmed by duplex ultrasonography among patients treated with dalteparin was substantially lower than among patients treated with enoxaparin, whereas the age-adjusted risk of a bleeding event in the dalteparin group was also lower than that in the enoxaparin group. Adjusted per capita costs of deep-vein thrombosis prophylaxis during the rehabilitation stay were $129 lower among subjects treated with dalteparin. CONCLUSION: The switch to dalteparin as a first-line therapy for deep-vein thrombosis prophylaxis in the rehabilitation period after total hip arthroplasty or total knee arthroplasty has led to substantial cost savings for Kessler Institute without compromising patient care.

Aged↗
PubMed1999

The sympathomimetic agent, 6-hydroxydopamine, accelerates cutaneous wound healing.

Using pharmacological stimulation of sympathetic terminals, the present study examines the role of sympathetic post-ganglionic neurons in cutaneous wound healing. Effects of local stimulation of sympathetic post-ganglionic neurons with 0.2 mg/kg 6-hydroxydopamine were studied on the healing of full-thickness skin incisions in rats. Epidermal wound healing was measured by a novel non-invasive quantitative method based on the increasing electrical resistance of healing skin. Dermal healing was determined by measuring wound breaking strength using an Instron Universal Testing device. We report a 35% increase in the rate of epidermal wound healing (P < 0.05. n(e) = 21, n(c) = 18) and a 43% increase in dermal strength (P < 0.05, n(e) = 13, n(c) = 10) after 6-hydroxydopamine treatment. Thus, our results show that pharmacological stimulation of sympathetic post-ganglionic neurons markedly accelerates skin wound healing at both the epidermal and dermal levels. This is the first study to show that peripheral nerve stimulation and specifically sympathetic stimulation accelerates cutaneous wound healing. We discuss these results in relation to neurogenic inflammation.

Animals↗
PubMed1996

Surgical wound healing monitored repeatedly in vivo using electrical resistance of the epidermis.

We describe a new transcutaneous electrical resistance method for measuring surgical wound healing which permits repeated measurements in vivo throughout the healing period. A saline-filled silver electrode was used to monitor the increasing ohmic resistance which accompanied the healing. Two validation studies were carried out. In the first study, histology on 16 rats showed that an intact stratum corneum was responsible for the high electrical resistance of skin, since lesions of the corneum markedly lowered the resistance. In the second study, electrical resistance readings of incisional wounds were taken repeatedly over 20 days in 13 rats: regression analysis showed that the healing slope for each incisional wound had a correlation coefficient r-value greater than 0.85. Moreover, all slopes were positive (p < 0.001) demonstrating that resistance increases as wound healing progresses and hence is a valid measure of healing. Test-retest resistance readings showed high reliability when measurements were repeated on the same wound (Pearson r = 0.94, n = 110). Hence we have shown that this new method is both valid and reliable. The device only monitors epidermal repair and gives no indication of wound strength. A modified device recently developed for humans has been used successfully on post-surgical wounds in numerous patients.

Animals↗
PubMed1993

A new method to study motoneuron regeneration using electromyograms shows that regeneration slows with age in rat sciatic nerve.

We developed a novel method for measuring motoneuron regeneration using transcutaneous electrical nerve stimulation to evoke electromyograms (EMGs). Using this technique we found that functional regeneration of the motoneurons of the rat sciatic nerve was significantly slower in 9-10-month-old rats (10 mo) than in 10-12 week old rats (3 mo). All rats received crush injuries of the sciatic nerve and were analyzed for reinnervation of the muscles in the foot by the novel EMG method on days 25, 29 and 33 post-surgery. There were significantly fewer test sites reinnervated in the foot of the older group. Fifty percent of the sites in the foot were reinnervated 27.2 days post-surgery in the 3 mo group in contrast to 33.7 days post-surgery in the 10 mo group, indicative of a 24% longer recovery period in the older animals. Rats were also assessed behaviourally with a behavioural test score (BTS). The BTS results correlated with the EMG findings demonstrating that our novel method measuring rate of recovery of EMGs is behaviourally relevant. We discuss the need to use animals older than 3 months for the study of 'adult' regeneration phenomena since 3-month-old rats may be somewhat immature. We applied this age principle and the novel EMG method in our accompanying paper which shows the acceleration of nerve regeneration by weak DC electric fields.

Aging↗
PubMed1993

Weak electric current accelerates motoneuron regeneration in the sciatic nerve of ten-month-old rats.

When a weak direct current (DC) of 10 microA driven by an implantable device was applied to a crushed sciatic nerve in 9-10-month-old rats, regeneration was accelerated as assessed electrophysiologically. Rats underwent a sciatic nerve crush of the right leg and were randomly assigned to one of three groups: (i) Cathode Distal (CD); (ii) Sham Implant (SI); or (iii) No Implant (NI). On post-operative days 25-39 each rat received a measurement of evoked electromyograms (EMG) in the foot. In addition each rat received a behavioural test score (BTS). This BTS correlated well with the evoked EMG results showing the behavioural relevance of the EMG results. NI rats performed the same as SI in the evoked EMG procedure, but CD rats performed significantly better than both the control groups. The recovery period in the CD rats was 21% shorter than in either the sham-treated or untreated controls showing that weak DC can greatly enhance nerve regeneration in adult rats. This result was in contrast to previous work in younger rats where DC treatments had no effects. The discrepancy is discussed in relation to the slowing of regeneration in older rats.

Aging↗
PubMed1992

Alterations in electrical pain thresholds by use of acupuncture-like transcutaneous electrical nerve stimulation in pain-free subjects.

Acupuncture-like transcutaneous electrical nerve stimulation (ALTENS) was compared with a placebo treatment in altering acute electrical pain thresholds. Ten pain-free subjects underwent, on different days, an acclimatization session, an ALTENS treatment, and a placebo treatment in a cross-over design. Electrical sensation and pain thresholds were measured from the tip of the index finger bilaterally at 15-minute intervals twice before, once during, and three times after a 30-minute treatment session. The ALTENS treatment was given at 4 Hz at an intensity just below pain threshold delivered to acupuncture points in the hand and wrist. The placebo treatment was similarly delivered, except that the intensity of stimulation was just above sensation threshold. Neither the ALTENS treatment nor the placebo treatment produced a significant change in pain threshold. There was no correlation between initial pain threshold and change in pain threshold. Implications for the modulation of pain are discussed.

Adult↗
PubMed1992

Acupuncture-like stimulation with codetron for rehabilitation of patients with chronic pain syndrome and osteoarthritis.

Acupuncture is one of the oldest healing methods which is used in traditional medicine. In the modern medicine, we are witnessing a renaissance of this ancient treatment applied mainly in the management of chronic pain. A number of modern technological changes are being applied to replace, or modify, the classical needle treatment. Among many modalities used today is the novel addition in Transcutaneous Electrical Nerve Stimulation (TENS) called CODETRON which delivers acupuncture-like stimulation in a random order. CODETRON was developed by a Canadian Scientist and had been evaluated in a clinical trial in a multidisciplinary pain clinic on patients who came for acupuncture therapy over a period of two years. Indications, effectiveness and experiences with this form of treatment are presented. In addition, results obtained from a six week double-blind randomized placebo controlled pilot trial of osteoarthritis of the hip/knee with CODETRON which was conducted later. The results were highly suggestive of the beneficial effect of this nonhabituating mode of therapy and confirmed our initial uncontrolled trial results.

Acupuncture Points↗
PubMed1990

Spinal sensory and motor tract activation after epidural electrical stimulation in the cat.

Somatosensory evoked potentials (SEPs) after peripheral nerve stimulation and motor evoked potentials (MEPs) after transcranial stimulation have been routinely used as monitors of the viability of pathways in the posterior and anterior spinal cord, respectively, in patients undergoing spinal cord surgery. To assess total spinal cord function, both of these procedures must be performed simultaneously, which is both cumbersome and technically difficult. The objectives of this study were to demonstrate both sensory and motor spinal tract activation after epidural electrical stimulation of the cat spinal cord. Thirty-seven adult mongrel cats were anesthetized with ketamine, intubated, and maintained with Ethrane and nitrous oxide. Stimulating electrodes were placed over the right dorsolateral spinal cord epidurally at T7 after a laminectomy. Recording electrodes were placed over the right L3 spinal cord epidurally, on the right L7 dorsal and ventral nerve roots, on the right and left sciatic nerves in the popliteal fossa, and in the right gastrocnemius muscle. After epidural stimulation of the spinal cord at T11, distinct reproducible potentials were recorded at each site. Activity in the L7 dorsal root implicated activation of spinal sensory tracts. Activity in the L7 ventral root and in the gastrocnemius implicated activation of spinal motoneurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Human basophil degranulation triggered by very dilute antiserum against IgE.

When human polymorphonuclear basophils, a type of white blood cell with antibodies of the immunoglobulin E (IgE) type on its surface, are exposed to anti-IgE antibodies, they release histamine from their intracellular granules and change their staining properties. The latter can be demonstrated at dilutions of anti-IgE that range from 1 x 10(2) to 1 x 10(120); over that range, there are successive peaks of degranulation from 40 to 60% of the basophils, despite the calculated absence of any anti-IgE molecules at the highest dilutions. Since dilutions need to be accompanied by vigorous shaking for the effects to be observed, transmission of the biological information could be related to the molecular organization of water.

Antibodies, Anti-Idiotypic↗
PubMed1988

Electroacupuncture suppresses a nociceptive reflex: naltrexone prevents but does not reverse this effect.

Rats were anesthetized with a continuous infusion of pentobarbital. First we showed that electroacupuncture (EA) suppressed the tail flick nociceptive reflex. Naltrexone (a long acting opiate antagonist) was given either intravenously or intrathecally to attempt to block this EA effect. The naltrexone prevented this EA effect when injected before the onset of EA treatment, but failed to reverse the EA effects when injected immediately after termination of EA treatment. We discuss the possibility that the endorphins set up a cascade effect whereby the subsequent EA suppression of tail flick is no longer dependent on endorphin and hence cannot be affected by opiate antagonists. This finding may clarify some of the confusion in the acupuncture endorphin literature.

Acupuncture Therapy↗
PubMed1988

Electroacupuncture suppression of a nociceptive reflex is potentiated by two repeated electroacupuncture treatments: the first opioid effect potentiates a second non-opioid effect.

Electroacupuncture (EA) produces suppression of the nociceptive tail flick reflex in rats. Two 10 min treatments given 90 min apart, cause a potentiation of the EA effect produced by the second treatment. This potentiation can be prevented by giving naltrexone before the first and second treatments (either intravenously or intrathecally administered). However, this potentiation cannot be reversed by naltrexone give only once, before the second EA treatment. These results suggest that the first EA effect which is opioid in nature, sets up a cascade effect, potentiating a second non-opioid EA effect.

Acupuncture Therapy↗
PubMed1987

Studies in suppression of nocifensive reflexes measured with tail flick electromyograms and using intrathecal drugs in barbiturate anesthetized rats.

We report on the effects of somatic conditioning stimuli on the reflexive nocifensive tail flick electromyograms (TFEMGs) in the rat anesthetized with continuous pentobarbital infusions. Rather than using a reflexive tail movement as a measure of noxious responses, TFEMGs were recorded from the base of the rat's tail as this gave more reliable results in the anesthetized state. In order to demonstrate the compatibility of this model with previous tail flick studies, we demonstrated an inhibition of TFEMGs by intrathecal morphine which was reversed by intravenous naloxone. The TFEMG latencies were then shown to be increased by electroacupuncture. This effect was antagonized by intrathecal naltrexone pretreatment. All of these results under barbiturate anesthesia resembled those observed previously in awake rats. The constant pentobarbital infusion maintained a stable baseline state, as reflected by TFEMG latencies and blood pressure recordings during the prolonged time-course of each experiment (approximately 1 h). We feel that this method of studying electroacupuncture suppression of nocifensive reflexes is valuable for its relative simplicity and reliability. It also has the virtue of avoiding the pitfalls of such studies in awake animals.

Anesthesia↗
PubMed1987

Application of weak electric field to the hindpaw enhances sciatic motor nerve regeneration in the adult rat.

Direct current (DC) electrical stimulation of the hindpaw is shown to enhance sciatic motor nerve regeneration in the adult rat. Cathodal stimulation, using weak currents (10 microA/cm2; field strength approximately 100 mV/cm) increased the reinnervation of the hindpaw muscles as measured by evoked electromyograms. This enhanced regeneration only occurred after cut-and-suture lesions, but not after crushing injury of the sciatic nerve. This enhancement of motor nerve regeneration by weak DC fields had been previously described in amphibians but we are the first to describe this phenomenon in mammals.

Animals↗
PubMed1987

Saphenous has weak ineffective synapses in sciatic territory of rat spinal cord: electrical stimulation of the saphenous or application of drugs reveal these somatotopically inappropriate synapses.

In a previous paper, we showed that chronic denervation of the sciatic nerve for more than 21 days in adult rats caused expansion of the saphenous nerve into sciatic territory in the spinal cord (medial L4, L5 and L6). To try to explain this expansion in the present paper, we tested the hypothesis that weak ineffective synapses of saphenous terminals are always present in sciatic territory. For this purpose the sciatic nerve was acutely denervated, the cord mapped with microelectrodes and responses evoked in single cells with natural (mechanical cutaneous) or electrical (pulses to saphenous nerve) stimulation. In the sciatic territory, no natural responses occurred but electrically evoked responses from the saphenous were everywhere. When drugs were applied to potentiate synaptic activity, many of the silent neurons in the sciatic territory in L4, L5 and L6 responded to natural inputs mediated by the saphenous. Picrotoxin was more effective than 4-aminopyridine which was more effective than strychnine in expressing these weak somatotopically inappropriate saphenous inputs. All together, these results support the hypothesis that weak ineffective saphenous inputs exist in sciatic territory of the spinal cord. They can be artificially expressed with electrical volleys or chemical potentiation and may be naturally expressed several weeks after chronic lesions of the sciatic nerve.

4-Aminopyridine↗
PubMed1987

Intrathecal diazepam suppresses nociceptive reflexes and potentiates electroacupuncture effects in pentobarbital-anesthetized rats.

Using noxious heat-evoked tail flick in rats anesthetized with pentobarbital infusion, we studied the effects of diazepam applied intrathecally. This drug caused a marked suppression of nociceptive reflexes in a dose-dependent manner. In addition, a small non-suppressive dose of diazepam potentiated electroacupuncture effects. These results are discussed in terms of gamma-aminobutyric acid (GABA) since it is known that diazepam enhances binding of GABA to its receptor and hence potentiates inhibitory effects of GABA in the spinal cord. The possible synergism of diazepam and pentobarbital is also discussed.

Acupuncture Therapy↗