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At least 37 records · Page 2Linked to original sources
PubMed1979

An analgesic action of intranvenously administered lidocaine on dorsal-horn neurons responding to noxious thermal stimulation.

Using extracellular single-unit recording techniques, effects of intravenously administered lidocaine on dorsal-horn nociceptive neurons were studied in cats made decerebrate whose spinal cords had been transected. Thirty-seven neurons in Rexed lamina V responding to high-threshold mechanical and noxious thermal stimuli (radiant heat, using Hardy-Wolff-Goodell dolorimeter) were studied. Lidocaine hydrochloride, 2.5, 5, and 10 mg/kg, iv, produced dose-related suppression of both spontaneous activity and responses of these neurons to noxious thermal stimulation. Spontaneous discharge frequencies at maximum suppression, observed 3--7 min after administration of each of the three doses of lidocaine were 64 +/- 14 (mean +/- 1 SE), 32 +/- 8, and 25 +/- 9 per cent of control values, respectively; responses to noxious thermal stimuli were 83 +/- 5, 52 +/- 8, and 39 +/- 7 per cent of the control values, respectively. Threshold skin temperature to noxious thermal stimulation increased from 44.7 +/- 0.4 C (control) to 46.3 +/- 0.7 C with lidocaine, 5 mg/kg (P less than 0.05), to 47.8 +/- 0.8 C with lidocaine, 10 mg/kg (P less than 0.01). The times necessary for recovery varied in a dose-related fashion. Plasma lidocaine concentrations 5 min after lidocaine, 5 mg/kg, averaged 3.6 +/- 0.7 microgram/ml. These data support the clinical impression that intravenously administered lidocaine produces analgesia at plasma concentrations of 3--10 microgram/ml. It is suggested that lidocaine may block conduction of nociceptive impulses, at least in part, by suppression of spinal-cord nociceptive neurons.

Analgesics↗
PubMedDate not supplied

Increased release of lymphokines by allografted mouse spleen cells following concanavalin A stimulation.

Using a test proposed in this laboratory for following macrophage "activation" (intracellular beta-glucuronidase content) and quantitative dilution studies, we have shown that lymphocytes from mice presensitized by a skin allograft release far more macrophage activating lympholines than do normal lymphocytes when non-specifically stimulated by concanavalin A. This difference may be due to latent metabolic changes of sensitized lymphocytes, but it may also express a modified balance among the various lymphocyte subpopulations within the spleen of grafted mice.

Animals↗
PubMed1977

Clinical assessment of analgesics using ultrasonic stimulation. A new method.

A quantitative method for measuring pain threshold by the use of ultrasonic stimulation in man was designed and the possibility of clinical application in assessing analgesics was investigated. Ultrasonic stimulus was given to Japanese subjects on the palmer distal part of the 2nd, 3rd and 4th fingers of both hands. The latent time between start of the stimulation and withdrawal of the hand when perceiving pain was considered the pain threshold. The ultrasonic evoked pain was a sharp pin-prick type, without sensations such as thermal and mechanical. The pain threshold lowered with increasing either stimulus intensity or water bath temperature when the hand of the subject was immersed during measurement. Normal threshold to ultrasonic stimulation measured in both 50 men and 50 women gave nearly normal distribution curves; women being more sensitive to ultrasonics than men. Analgesia with codeine phosphate (20 mg p.o.), aspirin (1.5, 1.0, 0.5 g p.o.), aminopyrine (100 mg p.o.) and mefenamic acid (500 mg p.o.) in volunteers of both sexes was demonstrated significantly using this method under double blind circumstances. Pentobarbital, diazepam, butylscopolamine, bromelain and placebo each in the usual dose used clinically failed to alter the pain threshold. Humans were at least 25 fold more sensitive than mice to the analgesics used herein.

Adolescent↗
PubMed1979

A reward-reduction model of depression using self stimulating rats: an appraisal.

A potential model of depression using a "reward reduction" technique with intracranial self-stimulation (ICSS) has been suggested. A number of rats with electrodes chronically implanted in the medial forebrain bundle were trained on this paradigm. The model involved the use of progressively increasing fixed ratio (IFR) schedules. Two tricyclic antidepressants, imipramine and protriptyline, were administered. Neither of these drugs resulted in the response enhancement which had been predicted. Only d-amphetamine (0.5 mg/kg) produced the predicted "antidepressant" action. It was concluded that response instability made this test difficult to operate and that even animals with adequately stable baselines did not produce a response pattern which could be categorised as specifically antidepressant.

Amphetamine↗
PubMed1979

Cortical slow negative waves following non-paired stimuli: effects of modality, intensity and rate of stimulation.

Using a simple stimulus counting task, negative after-waves following single (unpaired) stimuli were investigated under a variety of stimulus conditions. Responses were obtained to tones at 3 intensities, to light flashes at 3 intensities, and to tones at 3 rates of presentation. The acoustic stimuli led to a negative after-wave that peaked at frontal sites around 500 or 600 msec, and then trailed off to a more central scalp representation. This negative after-wave was increased in amplitude by slowing the rate of stimulus presentation. In comparison, no appreciable or sustained after-wave was elicited by visual stimuli. No significant effects in the negative after-wave were associated with intensity, either for visual or for acoustic stimuli. When analyzed by Principal Components Analysis, the negative after-waves were shown to comprise in all cases two underlying factors, although the factors contributed less to the total wave form for visual stimuli than for acoustic stimuli. Two interpretations for the negative after-wave were contrasted, one considering it to be an integral feature of the auditory evoked potential. A second interpretation, more compatible with the data obtained here, links the negative after-wave with non-specific activation processes.

Acoustic Stimulation↗
PubMed1978

Sensitive new in vitro bioassay for melanocyte-stimulating activity using the skin of Anolis carolinensis.

An accurate, highly reproducible and sensitive bioassay for melanocyte-stimulating hormone (MSH) using the skin of Anolis carolinensis in vitro is described. The time taken for green Anolis skin fragments to change to a specific, visually assessed, green-brown color is dose-related, and this forms the basis of the new assay. The method is simple to perform, and 1 person may assay 20 samples in a day using the dorsal skin from a single adult lizard. The mean dose-response ranges between 48 X 10(-12) and 375 X 12(-12) M (38 to 625 pg/ml). Using the assay, alpha-MSH, beta-MSH, ACTH (4-10), and ACTH (1-10) were equipotent on a molar basis. For repeated bioassay of rat pituitary extracts, the dose-response curves were highly significant, and only 1 of the 9 pituitary dose-response curves deviated significantly from the slope of the standard alpha-MSH curve. The index of precision, lambda, for the 9 pituitary bioassays ranged between 0.037 and 0.081, while the mean 95% fiducial limits were -6.6 and 7.1% on either side of the estimated potency. The new rate method is compared with an earlier quantal method which also uses the isolated skin of Anolis carolinensis. The quantal method does not have dose-response characteristics and is therefore less accurate and reproducible than the new method; the coefficient of variation for repeated bioassay of the same pituitary extracts ranged from between 12 to 20% for the quantal method and between 2.9 to 5.7% for the new rate method.

Adrenocorticotropic Hormone↗
PubMed1976

A new analgesic testing method using ultrasonic stimulation. I. Effects of narcotic and nonnarcotic analgesics.

A quantitative method for measuring pain threshold by the use of ultrasonic stimulation in mice has been designed. The method had the advantage of precision, simplicity of technique, rapidity of measurement, and the fact that the stimuli is innocuous upon repeated application. The nature of the senstaions induced by ultrasonic stimulus is somewhat like that felt with a prick type of pain. Pentazocine (30, 100, 150 mg/kg i.p.) aminopyrine (15,50, 100, 150 mg/kg i.p.), phenacetin (100,150, 200, 250 mg/kg i.p.) sodium salicylate (150, 200, 250 mg/kg i.p.) and other antipyretic analgesics were active in a wide range of doses indicating that this technique is sensitive to the narcotic antagonist and to the weak analgesics as well as to the narcotic analgesics as well as to the narcotic analgesics such as morphine (2.5, 5, 10, 15 mg/kg i.p.), codeine (10, 20, 25, 30, 50 mg/kg i.p.) and pethidine (5,10, 15, 20, 25 mg/kg i.p.). The ultrasonic method is, therefore, applicable in screening procedures when attempting to evaluate the analgesic potency of a wide variety of chemical agents.

Age Factors↗
PubMed1975

Re-introduction and evaluation of an accurate, high capacity bioassay for melanocyte-stimulating hormone using the skin of Anolis carolinensis in vitro.

A simple and rapid assay for the quantitative determination of melanocyte-stimulating hormone (MSH) activity, using skin fragments of the lizard Anolis carolinensis in vitro, is described in detail. This assay, in which a quantal response (e.g. induction of a brownish-green colour) can be detected by visual observation, allows determination of MSH activity in up to 50 samples/day by one person, using the skin of one lizard. The mean dose found to induce this colour change was 0-15 ng synthetic alpha-MSH/ml (range 0-02-0-5 ng/ml). The assays shows high accuracy, reproducibility and specificity. Anterior and posterior lobe hormones as well as pituitary catecholamines do not interfere with the determination of pituitary MSH activitymthe method is compared with the assay using hypophysectomized frogs (Rana pipiens) in vivo. Determinations of MSH in pituitary extracts by both methods gave quantitatively similar results when determined with alpha-MSH as the reference substance. However, when beta-seryl MSH was used as a reference, the two assays gave different results for the MSH activity of the pituitary extractsmthis indicates that MSH from the rat pituitary gland has a biological activity similar to that of alpha-MSH rather than to that of beta-seryl MSH.

Adrenocorticotropic Hormone↗
PubMed1977

Changes in the electroencephalogram accompanying the use of stimulant drugs (methylphenidate and dextroamphetamine) in hyperactive children.

Fifteen hyperactive boys aged 5.6-10.6 years had their electroencephalograms (EEG) recorded during performance of a simple reaction task while on stimulant medication (methylphenidate or d-amphetamine) and after being free of medication for at least 48 hr. Interval histograms were formed from measurements of the duration of 780 half waves taken from predetermined portions of the EEG'S recorded from the left parietal-occipital derivation for both treatment conditions, and the histograms were subjected to a central-moments analysis. Previous evidence showed that, in normal children, smaller-valued 2nd, 3rd, and 4th central moments were associated with greater maturity. The EEG histograms obtained while the hyperactive children were taking stimulant medication had significantly (p less than 0.005) smaller 2nd, 3rd, and 4th central moments than the histograms of the same children obtained when off medication. Age of the group predicted from the means of the 2nd, 3rd, and 4th central moments of the EEG interval histograms was 91 months when the children were off medication--9 months less than the group's actual mean age. Age predicted in the same way when the children were on medication was 97 months. Findings support the concept of a neurophysiological maturational lag in hyperactivity and suggest that this lag is overcome, in part, by the use of stimulant drugs.

Attention↗
PubMed1978

Intermittent photic stimulation. Clinical usefulness of non-convulsive responses.

The clinical usefulness of non-convulsive responses induced by intermittent photic stimulation (IPS) was studied in 46 patients whose evaluation included both electroencephalography (EEG) and computerized cranial tomography (CT scan). Three patterns of photic responses were identified and related to background EEG activity and type of lesion seen on CT scan. An asymmetry in photic driving manifested only by a consistent amplitude difference greater than 50% was rarely associated with other EEG changes such as focal slowing or significant asymmetry in the alpha rhythm. In contrast, an asymmetry in development of the photic response correlated well with ipsilateral focal slowing and CT scan evidence of parenchymatous brain disease. Bilateral, symmetrical high amplitude single spikes evoked by individual light flashes were seen only in patients with diffuse encephalopathies. In no patient with structural brain disease as judged by CT scan was an abnormality in IPS the only EEG finding. There was also no apparent relationship between the anatomical site of a focal cerebral lesion and the type of response induced by IPS. Photic stimulation is of limited value in non-epileptic patients. Little clinical significance can be attached to nonconculsive responses in the absence of associated EEG changes which by themselves are generally more informative.

Adult↗
PubMed1978

Transcutaneous electrical stimulation. Its use in the management of postoperative pain.

Forty patients who were to have total hip replacement were randomly allocated to two groups. One group received intramuscular pethidine (30 mg) alone for postoperative analgesia in the first 24 h, the other received transcutaneous stimulation (TES) and pethidine as necessary. The use of pethidine was compared in the two groups under standardised conditions of time, operative and anaesthetic techniques. There was less pethidine used in the TES group. The technique is simple and non-invasive and can be used continuously. It was well accepted by both patients and staff. The electrodes must be prepared carefully and placed accurately. An ideal stimulation effect was often achieved by similar patterns of stimulating parameters.

Aged↗
PubMed1978

Effect of hydrocortisone on bioelectric activity and morphological pattern of spinal cord in frogs.

The effect of 1 mg hydrocortisone (HC) administered 3 h before the experiment was studied the bioelectric activity of ventral roots of spinal cord, the size and morphology of motoric neurons and also the size of synaptic endings being measured under different frequency of electric stimulation in frogs. It was found that the effect of HC on the electric activity of spinal cord and morphology of its neural elements was dependent on the stimulation used. Under the resting conditins the administration of HC resulted in a small decrease of the size of neurons. Under a low frequency stimulation HC did not affect the electric activity of spinal cord, but prevented the swelling of neurons and of synaptic endings resulting from the stimulation. Under a high frequency stimulation themorphology of neurons was remarkably changed, a shrinkage of these and an appearance of "dark" cells being found. Also these changes were prevented by the administration of HC. It was concluded that in all experiments HC prevented the changes resulting from electrostimulation, its effect, however, being dependent on the parameters of the stimulation used.

Animals↗
PubMed1978

Investigations on latent erythropoietin (ESF) deficiency in non anemic patients with chronic renal disease using hypoxic stimulation methods.

So far the question has not been elucidated whether latent ESF-deficiency exists in patients with chronic renal disease during initial development of renal anemia. Therefore, ESF was determined in urine and serum of non anemic patients being exposed to acute hypoxia: 8 healthy volunteers and 8 patients who had a Ccreat below 48 ml/min were studied while in a hypobaric chamber for 4 subsequent periods of 10 h each (simulated maximal altitude 4000 m INA = 462 mm Hg). We also determined plasma iron turnover and reticulocyte counts. 10 h after the study began, the patients showed a significantly higher ESF-level than the normal volunteers. In the course of 48 h collection periods of urine under hypoxic conditions the mean ESF excretion in patients corresponded to 9.9 and in healthy persons to 7.3 Units. With regard to plasma iron turnover and reticulocyte count an increase was shown, but no significant differences existed between the two groups. A latent ESF-deficiency as the initial cause of renal anemia does not exist.

Adult↗
PubMed1978

Evaluation of effect of acetylsalicylic acid using electrical stimulation on the forefinger of healthy volunteers.

1 In order to determine the optimal level of electrical stimulation, the degree of pain sensitivity produced by electrical stimulation on the volar side of terminal phalange of the right forefinger was studied in 22 male and female volunteers between the ages of 20 and 27 years. 2 A stimulation frequency of 400 Hz, width of 0.1 ms and electrical potential of 55 V was found to be optimal for study fo analgesics. 3 The effect of acetylsalicylic acid was studied in 40 healthy male volunteers between the ages of 20 and 25 years. Electrical stimulation was applied for 5 s under a single-blind method at a frequency of 400 Hz, width of 0.1 ms and electrical potential of 25, 35 and 55 V. Placebo, 250 mg, 500 mg and 1 000 mg of acetylsalicyclic acid were administered orally under double-blind method conditions. 4 As a result of this study, it was found that acetslsalicylic acid in a dose of 500 and 1 000 mg, was effective in relieving pain with statistically significant differences from a placebo.

Adult↗
PubMed1977

Immune neutrality of calf skin collagen gel used to stimulate revitalization in pulpless open apex teeth of rhesus monkeys.

A collagen mineral gel has recently been shown to stimulate revitalization of pulpless open apex teeth when syringed into debrided root canals. Experiments were conducted to examine possible stimulation of the immune system by the experimental procedure. Ring tests (interface precipitation analysis), Ouchterlony plates and hemagglutination tests on plasma samples taken from experimental rhesus monkeys throughout the healing process indicate a complete lack of humoral immune responsiveness to the injected collagen.

Animals↗