Cardiovascular autonomic response during preoperative stress and postoperative pain

Heart rate response to physiologic maneuvers was used to evaluate autonomic nervous system (ANS) function in normal control subjects and during the stress and pain experienced by patients before and after surgery. In preoperative patients (stressed without pain) and postoperative patients (stressed with pain), maneuvers which routinely increase activity in the parasympathetic or sympathetic divisions of the ANS produced only 50% of the response seen in control subjects. The heart rate response was not further reduced in patients with pain compared to patients with stress alone. The difference in heart rate response between surgical patients and control subjects was not accompanied by a difference in baseline heart rate. The data suggest that tonic stress impairs the ability of the ANS to respond fully to perturbing influences.     

Potentiation of morphine antinociception by monoamine reuptake inhibitors in the rat spinal cord

Potentiation of the antinociceptive effects of morphine by the tricyclic antidepressants was assayed in awake restrained rats using the tail-flick test. Intrathecally administered amitriptyline, desipramine or sertraline at doses that had no effect themselves (25-30 micrograms) potentiated a subthreshold parenteral dose of morphine (0.5 mg/kg). The morphine potentiating effect of amitriptyline was prevented by prior administration of parachlorophenylalanine (PCPA). This effect of PCPA was not restored by 5-hydroxytryptophan (5-HTP) but was restored when the animals were left for 14 days to replete. The morphine potentiating effects of amitriptyline, desipramine and sertraline were blocked by intrathecal administration of low doses of the serotonin antagonist methysergide and the alpha-adrenergic antagonists yohimbine and phentolamine but not by the beta-adrenergic antagonist propranolol. The results are consistent with the hypothesis that the potentiation of morphine's antinociceptive effect by tricyclic antidepressants depends on activation of both spinopetal serotonin and adrenergic neurons.     

Reversal of morphine and stimulus-produced analgesia by subtotal spinal cord lesions

This study examined the hypothesis that descending inhibitory pathways from brain stem to spinal cord mediate the analgesic effect of both electrical brain stimulation and morphine. In the first set of experiments, the effect of subtotal midthoracic spinal cord lesions on the analgesic effect of electrical stimulation in the periaqueductal gray matter of the rat was examined. In the second, the effect of similar cord lesions on the analgesic effect of intraperitoneal morphine was studied. In both cases, a lesion of the dorsal part of the lateral funiculus (DLF) reduced or abolished the analgesia of the hindlimbs. Analgesia of the forelimbs was unaffected. Lesions of the dorsal columns, which include the corticospinal tract, or lesions of the ventral part of the lateral funiculus had no effect on analgesia. It is concluded that an inhibitory pathway, which descends in the dorsal part of the lateral funiculus and which probably originates in the nucleus raphe magnus of the medulla, mediates the descending control found in both morphine and stimulus-produced analgesia.     

Mechanism of interference by chelating agents and sucrose in radioimmunoassay of angiotensin I.

EDTA, 2,3-dimercaptopropanol and sucrose were shown by Scatchard analysis to interfere in the radioimmunoassay of angiotensin I by altering the affinity, but not the capacity, of antibody for antigen. It is stressed that when interfering reagents are present in samples the assay result must be obtained from a standard curve in which each standard contains the interfering reagent(s) at a similar concentration as present in each sample mixture.     

Specific radioactivity of radioimmunoassay tracer determined by self-displacement: a re-evaluation.

A gas Chromatographie procedure with flame ionisation detection has been developed to measure 2-phenylethylamine in human urine as the trifluoroacetyl derivative. The amine is purified by an ether extraction procedure and derivatised with trifluoroacetic anhydride. Quantification is obtained by comparing the peak height with that for an internal standard added to the urine before extraction.The normal 24-h excretion value for 2-phenylethylamine in human urine is found to be 6.8 ± 2.9 Mg (mean ± S.D.).     

The majority of unmyelinated afferent axons in human ventral roots probably conduct pain

Three patients with intractable chest pain had undergone dorsal rhizotomy. None had obtained relief, but all three had developed dysesthesia and hyperesthesia, in addition to the original pain persisting in the supposedly deafferented area. Dorsal ganglionectomy was performed for these 3 patients in 1976 and they were followed for 3 years. Following ganglionectomy two of the three developed total anesthesia, including loss of dysesthesia, hyperesthesia, and the original pain.Light and electron microscopical examination of the ventral roots removed at the time of ganglionectomy showed that unmyelinated axons constituted approximately 25% of the total fiber count. Two ventral roots from one patient who previously had serendipitous removal of dorsal ganglia showed a marked reduction in the population of unmyelinated axons. The observations support Coggeshall's contention that the majority of unmyelinated axons in the ventral roots are sensory and probably conduct pain.     

A new variant mucolipidosis: Biochemical investigations on two siblings

Biochemical studies are presented on two siblings with some features of Mucolipidosis III, but with distinctive clinical findings. Levels of β-galactosidase, -mannosidase, β-glucuronidase, N-acetyl-β-glucosaminidase and -fucosidase found in serum from these patients ranged from 10 to 100 times higher than normal. The ratio of heat stable to heat labile serum isoenzymes of N-acetyl-β-glucosaminidase is considerably greater than normal.

An extremely low activity of β-galactosidase was found in fibroblasts cultured from one patient. Levels of the remaining enzymes were in the low normal range. Similarly, β-galactosidase levels were low in heart, kidney, liver, spleen and lung of one patient who died during the course of the study. Activities of the remaining enzymes were close to normal.

No excessive excretion of mucopolysaccharide was noted, however, changes in distribution of several fractions were found. Mucopolysaccharide labeled with radioactive sulfate was degraded by cultured fibroblasts at a normal rate.

In addition to clinical differences, the biochemical studies further demonstrate the uniqueness of these patients.     

Partial antagonism of placebo analgesia by naloxone

Thirty subjects were given a placebo (intravenous saline), which was described as a known pain killer, once a week for 3 consecutive weeks. Experimental ischemic arm pain was produced prior to the placebo and again 1 h later. In a double blind procedure, half of the subjects received 10 mg of naloxone after placebo; the remaining subjects received naloxone vehicle. In addition to the placebo session, there were control and naloxone sessions each week to determine the normal changes in pain and the effect of naloxone on the pain, respectively, when no placebo was given. Significant placebo-induced analgesia was demonstrated, and a group of consistent placebo responders was identified. Although naloxone alone had no effect on the experimental pain, naloxone diminished the analgesic effectiveness of the placebo, suggesting that endogenous opioids are involved in producing placebo-induced analgesia.     

Naloxone fails to reverse pain thresholds elevated by acupuncture: acupuncture analgesia reconsidered

We were unable to demonstrate the reversal of dental acupunctural analgesia following the injection of 0.4 mg naloxone using evoked potential methodology. Since our findings differed from those of Mayer, Price and Rafii who used pain threshold methods, we attempted to replicate their study. Subjects who demonstrated acupunctural analgesia during electrical stimulation of the LI-4 point on the hands received either 1.2 mg naloxone or normal saline under double blind conditions. Pain thresholds elevated by acupuncture failed to reverse when naloxone was given. Review of experimental design issues, other related human subjects research, and animal studies on acupunctural analgesia provided little convincing evidence that endorphins play a significant role in acupunctural analgesia. Because endorphins can be released in response to a stressor, endorphin presence sometimes correlates with acupunctural treatment in animal studies and some human studies, especially those involving pain patients. The primary analgesia elicited by acupunctural stimulation seems to involve other mechanisms.     

Tryptophan loading may reverse tolerance to opiate analgesics in humans: A preliminary report

Five patients on chronic opiate medication to treat low-back and leg pain were determined to have developed opiate tolerance on the basis of their failure to obtain significant relief (rated on a subjective pain scale and by the degree of straight leg-raising they were able to endure) after receiving 30 mg of morphine administered i.v. in divided doses over 35 min. After these patients' diets had been supplemented with 4 g/day of l-tryptophan for 2–9 weeks, they achieved significant relief from pain when the opiate tolerance test was re-administered, and were able to lead more active lives while reducing their daily opiate intake. Chronic opiate administration probably reduces the serotonin turnover rate in the central nervous system; it may be that this is reversed by loading with the serotonin precursor, l-tryptophan.     

Tertiary gain and chronic pain

The authors present a brief review of the role of primary and secondary gain in chronic pain patients. The concept of tertiary gain is discussed. Case presentations are offered to illustrate the various types of gain and the roles they play in chronic pain problems. The discussion involves the conceptualization of gain and its part in the evaluation of chronic pain patients.     

Does the MMPI differentiate chronic illness from chronic pain?

This study examines the relationship between MMPI scales and functional limitation for the chronic illness populations of chronic low back pain, migraine headache, hypertension and diabetes. Average MMPI profiles for these groups approximate those of previous studies with the chronic low back group having the most disturbed profile and showing elevations especially on the Hs, Hy and D scales. Several kinds of analyses, however, demonstrate that, in general, the MMPI group differences can be accounted for by individual self-rated functional limitation. The data do not support attempts at defining a low back pain or chronic pain personality profile apart from the emotional disturbance associated with chronic limitation and disruption of activity.     

Analgesic plasma concentrations of morphine in children with terminal malignancy receiving a continuous subcutaneous infusion of morphine sulfate to control severe pain

Three children with terminal malignancy received a continuous subcutaneous infusion of morphine sulfate for the control of severe pain, the morphine dose being adjusted until the patient and/or parent reported complete freedom from pain. Analgesic plasma morphine concentrations at the steady state in these patients ranged from 12.9 to 57 ng/ml (median 19.6 ng/ml) while receiving morphine doses of 0.45-2.0 mg/h (0.034-0.06 mg/kg/h). One patient, who received 2 mg morphine per hour for 12 days demonstrated a 2-fold variation in steady-state plasma concentration during this period.     

Determination of chromium in feces by atomic absorption spectrophotometry

Cord blood of 300 randomly selected healthy full-term newborn babies (98 Chinese, 102 Malays and 100 Indians) was examined for maternal—foetal blood group incompatibility, haemoglobin types, glutathione level and activities of glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, pyruvate kinase and methaemoglobin reductase, and each newborn's total plasma bilirubin level was estimated daily for one week. 5.6% of the babies developed severe hyperbilirubinaemia of 15 mg/100 ml or higher, three requiring exchange blood transfusion. Babies with maternal—foetal blood group incompatibility and glucose-6-phosphate dehydrogenase deficiency had significantly higher mean bilirubin curves than “normal” babies. Among newborns without known abnormalities Chinese had the highest mean bilirubin curve, Indians the lowest. In all three races, maximum bilirubin level was reached on the fourth day. Neonates with low glutathione reductase activity had a significantly higher mean bilirubin curve. No such pattern was seen for glutathione, glutathione peroxidase, pyruvate kinase or methaemoglobin reductase.     

Derivation of decision rules to predict clinically important outcomes in acute flank pain patients

Objective

Routine CT for patients with acute flank pain has not been shown to improve patient outcomes, and it may unnecessarily expose patients to radiation and increased costs. As preliminary steps toward the development of a guideline for selective CT, we sought to determine the prevalence of clinically important outcomes in patients with acute flank pain and derive preliminary decision rules.

Childhood pain: the school-aged child's viewpoint

This interview study was designed to obtain a substantial body of information about childhood pain from a large cohort (n = 994) of Northern Californian school children between the ages of 5 and 12 years. The primary criteria for assignment to groups were extent of hospitalization experience, recency of hospitalization, presence of a painful chronic condition, and chronic iatrogenic pain. Open-ended questions were used to determine the extent of the children's knowledge and understanding of pain, their ability to describe pain, specific pain experiences, use of coping strategies, preferences concerning the timing of information about impending pain, and maladaptive pain usage. There was unequivocal evidence of the children's ability to communicate effectively concerning their pain, however, knowledge and understanding of pain for most of the sample was at a low developmental level, with no clearly defined age trends and no sex differences. There was relatively low use of coping strategies and the frequency of maladaptive pain usage was disquieting.     

Aspirin clearly depresses responses of ventrobasal thalamus neurons to joint stimuli in arthritic rats

This study dealt with the effect of aspirin upon activities of 17 ventrobasal thalamic neurons recorded in 17 rats rendered arthritic by injection of Freund's adjuvant into the tail. These neurons presented reproducible responses to mobilization and/or mild lateral pressure on a joint and were recorded for at least 40 min after aspirin administration. After intravenous injection of aspirin at the dose of 50 mg/kg (13 neurons tested), there was a progressive decrease in the number of spikes in the discharges. The maximum effect occurred at 30 min where the mean value of the response expressed as a percentage of the control was m = 34.62 +/- 7.5% (n = 13, p less than or equal to 0.001). Recovery was progressive and could be considered as complete at 60 min. By contrast, no significant modification of the spontaneous firing has been observed. With lower doses of aspirin (12.5 or 25 mg/kg tested with 4 neurons) there was respectively no clear depressive effect or only a transient decrease of the response.