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Biomedical subjects

Paul Green

Publications and source records attributed to Paul Green.

9 recordsLinked to original sources
PubMed2003

Vagal modulation of spinal nicotine-induced inhibition of the inflammatory response mediated by descending antinociceptive controls.

Noxious stimuli activate neuroendocrine axes, inhibiting inflammation, an effect that is powerfully attenuated by ongoing activity in subdiaphragmatic vagal afferents. To evaluate whether this inhibitory effect of vagal afferent activity is mediated by descending antinociceptive control, we tested whether antagonizing descending antinociceptive controls: (i) enhances the inhibition of inflammation produced by spinal nicotine (which stimulates central terminals of nociceptors) and (ii) occludes the enhancing effect of subdiaphragmatic vagotomy, in the rat. Spinal intrathecal co-administration of the alpha-adrenergic receptor antagonist phentolamine and the non-selective opioid receptor antagonist naloxone, and acute subdiaphragmatic vagotomy each produced enhancement, with similar magnitude, of nicotine-induced inhibition of plasma extravasation, produced by the potent inflammatory mediator, bradykinin. The combination of subdiaphragmatic vagotomy and intrathecal receptor antagonists, however, produced no further enhancement compared to each treatment alone. These findings support the suggestion that activity in descending antinociceptive controls modulates noxious stimulus-induced inhibition of inflammation and the vagal modulation of noxious stimulus-induced inhibition of inflammation is mediated by descending antinociceptive controls.

Adrenergic alpha-Antagonists↗
PubMed2003

Word memory test performance in children.

One-hundred and thirty-five children between the ages of 7 and 18 years were evaluated clinically. Their diagnoses included Fetal Alcohol Syndrome (FAS) or Effects, Schizophrenia, Bipolar Mood Disorder, various neurological diseases, Attention Deficit Hyperactivity Disorder (ADHD), Conduct Disorder, Oppositional-Defiant Disorder and learning disabilities. As part of a comprehensive neuropsychological assessment, the children were given the Word Memory Test (WMT; Green, Allen, & Astner, 1996; Green & Astner, 1995), containing various subtests which measure, respectively, effort and verbal memory. Although age and verbal intelligence are known to affect scores on most ability tests, they were not found to be significant determinants of WMT effort scores. Younger children did not score any lower on the effort subtests than older children. The children scored as well as a group of parents seeking custody of their children and they scored higher than adult patients with mild head injuries. The computerized WMT requires some basic reading skills and some children with lower than a grade 3 reading level scored at a relatively low level on the effort subtests. The current data suggest that most children with at least a grade 3 reading level can pass the WMT using the adult criteria. It is concluded that the WMT is potentially useful in the evaluation of effort during pediatric neuropsychological evaluations. Further research is needed to replicate these findings and to develop child norms for the memory subtests.

Adolescent↗
PubMed2003

Relationships between olfactory discrimination and head injury severity.

The goal of this study was to examine the relationship between brain injury severity and scores on both an olfactory identification test and on many widely used neuropsychological tests in 367 patients with head injuries of varying levels of severity. It was hypothesized that valid olfactory test scores would correlate highly with injury severity because both the olfactory nerves and the primary olfactory cortices are especially vulnerable to damage in closed head injury. After removing data of doubtful validity from cases failing effort tests, olfactory test scores were related to Glasgow Coma Scale scores (GCS), post-traumatic amnesia and radiological abnormalities more strongly than any of the neuropsychological test scores. Based on the assumption that post-traumatic amnesia is caused by a different mechanism than loss of core consciousness, it was also predicted that there would be no cases with a GCS less than 13 and with no post-traumatic amnesia. As predicted, there were no cases in this group. The results support previous studies showing greater olfactory impairment with increased severity of head injury.

Adult↗
PubMed2002

Altered nucleus accumbens circuitry mediates pain-induced antinociception in morphine-tolerant rats.

We investigated the effect of chronic administration of morphine on noxious stimulus-induced antinociception (NSIA) produced by intraplantar capsaicin injection. In the untreated (naive) rat, we previously found that NSIA depends on activation of dopamine, nicotinic acetylcholine, and mu- and delta-opioid receptors in nucleus accumbens. Rats chronically implanted with subcutaneous morphine pellets demonstrated tolerance to the antinociceptive effects of acute systemic morphine administration but did not show cross-tolerance to NSIA. Morphine pretreatment, however, significantly reduced NSIA dependence on intra-accumbens opioid receptors but not on dopamine or nicotinic acetylcholine receptors. As observed in naive rats, intra-accumbens microinjection of either the dopamine receptor antagonist flupentixol or the nicotinic receptor antagonist mecamylamine blocked NSIA in rats tolerant to the antinociceptive effects of morphine, but, in contrast to naive rats, intra-accumbens microinjection of either the mu-receptor antagonist Cys2,Tyr3,Orn5,Pen7 amide or the delta-receptor antagonist naltrindole failed to block NSIA. These findings suggest that although NSIA is dependent on nucleus accumbens opioid receptors in the naive state, this dependence disappears in rats tolerant to the antinociceptive effects of morphine, which may account for the lack of NSIA cross-tolerance. In separate experiments, intra-accumbens extracellular dopamine levels were measured using microdialysis. Dopamine levels increased after either capsaicin or systemic morphine administration in naive rats but only after capsaicin administration in morphine pretreated rats. Thus, intra-accumbens dopamine release paralleled antinociceptive responses in naive and morphine pretreated rats.

Animals↗
PubMed2002

Detecting exaggeration and malingering with the trail making test.

The purpose of this study was to examine whether unusual performance on the Trail Making Test could be indicative of deliberate exaggeration. Participants were 571 patients seen as part of a hospital trauma service who had acute traumatic brain injuries, and 228 patients involved in head injury litigation. As expected, the hospital patients with more severe traumatic brain injuries performed more poorly than the patients with less severe brain injuries on Trails A and Trails B. Cutoff score tables were developed for the patients with acute traumatic brain injuries for the total sample and by injury severity groups. Scores falling at or below the 5th percentile were considered suspicious for possible exaggeration. The performances of the head injury litigants who exaggerated on at least one well-validated symptom validity test were compared to these cutoffs. Very high positive predictive values for individuals with very mild head injuries on Trails A and B were identified (i.e., both 100%); lower positive predictive values were obtained for individuals with more severe head injuries (55.6-60%). The negative predictive values were only moderate (range=66.4-78.2%), and the sensitivity was very low (range = 7.1-18.5%) for all groups. Scores that fall in the range of possible biased responding should be considered "red flags" for the clinician because they likely do not make biological or psychometric sense. However, the sensitivity of the test for deliberate exaggeration is very low, so clinicians who rely on this test in isolation to identify deliberately poor performance will fail to identify the vast majority of cases.

Adult↗
PubMed2002

The use of an earplug to increase speech comprehension in a subgroup of children with learning disabilities: an experimental treatment.

In this article, the ability to comprehend and repeat short stories was measured in selected children with learning difficulties. Performances were compared in 3 listening conditions, in which stories were heard either in the left ear, in the right ear, or in both ears simultaneously. Although the underlying mechanisms are not understood, some children are better able to repeat stories presented to 1 ear only than to both ears simultaneously. This effect warrants further study because it leads to a simple noninvasive treatment method that might be of significant benefit to some children. In a follow-up study by the Department of Education of the Alberta government, children from this study were independently retested and the study's main findings were replicated.

Adolescent↗
PubMed2002

Laypersons' expectation of the sequelae of whiplash injury. A cross-cultural comparative study between Canada and Lithuania.

BACKGROUND: The objective of the present study is to compare the frequency and nature of expected 'whiplash' symptoms in Lithuania (a country where the late whiplash syndrome is rare or unknown) with that in Canada. MATERIAL/METHODS: A symptom checklist was administered to 2 subject groups selected from local companies in Kaunas, Lithuania, and Edmonton, Canada, respectively. Subjects were asked to imagine having suffered a neck sprain (whiplash injury) with no loss of consciousness in a motor vehicle accident, and to check which, of a variety of symptoms, they would expect might arise from the injury. For symptoms they anticipated, they were asked to select the period of time they expected those symptoms to persist. RESULTS: In both the Lithuanian and Edmontonian groups, the pattern of symptoms anticipated closely resembled the acute symptoms commonly reported by accident victims with acute neck sprain, but while up to 50% of Edmontonians also anticipated symptoms to last months or years, very few Lithuanian subjects selected any symptoms as likely to persist. CONCLUSIONS: In Lithuania, despite the documented occurrence of neck sprain symptoms in some 50% of individuals following motor vehicle accidents, there is a very low rate of expectation of any sequelae from this injury. What current or previous aspects of society that underlie this remain uncertain. This lack of expectation of chronicity in Lithuania may, in part, determine the low prevalence of the late whiplash syndrome there. Further studies of symptom expectation as an etiologic factor in the late whiplash syndrome are needed.

Accidents, Traffic↗
PubMed2002

Depressive symptoms and neurocognitive test scores in patients passing symptom validity tests.

This study examined the effect of depression on neurocognitive performance in patients who passed symptom validity testing. The Beck Depression Inventory (BDI) was used to assess depression in 420 patients with heterogeneous referral diagnoses (more than half of these cases were head injury or neurological disease). All patients had demonstrated satisfactory effort by passing two symptom validity tests. No differences were found on objective cognitive and psychomotor measures in groups sorted based on their self-reported depression. In contrast, on the self-report measures [i.e., Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Symptom Checklist-90-Revised (SCL-90-R), and Memory Complaints Inventory (MCI)], differences were found indicating that patients with depression report more emotional, somatic, and cognitive problems. Contrary to expectation, these data suggest that depression has no impact on objective neurocognitive functioning.

Journal Article↗