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Biomedical subjects

L G Allan

Publications and source records attributed to L G Allan.

35 records · Page 2Linked to original sources
PubMed1989

Color aftereffect contingent on text.

During adaptation, two different letter strings (each five or six letters) were presented to subjects alternately, one in green and the other in magenta. The extent to which these letter strings subsequently elicited a color aftereffect was assessed. In different experiments, the chromatic letter strings consisted of words and nonwords. The results indicated that letter strings that form English words can contingently elicit a color aftereffect. This was the case even when the words were anagrams. There was no evidence that nonword letter strings could contingently elicit such an aftereffect, even when the nonwords conformed to English orthography. The results are relevant to understanding other contingent color aftereffects (McCollough effects), illusory color noted by computer operators who work at monochrome (green or amber) displays, and the processing of text.

Adult↗
PubMed1988

Plasma glutathione S-transferase concentration as a measure of hepatocellular integrity following a single general anaesthetic with halothane, enflurane or isoflurane.

The plasma concentration of hepatic glutathione S-transferase (GST) was measured in matched groups of patients who received halothane, enflurane or isoflurane anaesthesia for elective minor surgery. The GST concentrations increased significantly at 3 h after anaesthesia in patients who received halothane or enflurane, but not in patients who were given isoflurane. A secondary increase in GST concentration, at 24 h, was seen in a small number of individuals who received halothane or enflurane. Abnormal GST concentrations were found in 50% of patients following halothane anaesthesia, 20% following enflurane and 11% after isoflurane. The small but significant increases in GST concentrations in patients receiving halothane or enflurane suggests an impairment of hepatocellular integrity following the administration of these anaesthetics. In contrast, isoflurane anaesthesia did not appear to be associated with this effect.

Adult↗
PubMed1987

Hepatic glutathione S-transferase release after halothane anaesthesia: open randomised comparison with isoflurane.

Plasma concentrations of hepatic glutathione S-transferase (GST) are a more sensitive measure of acute hepatic damage than aminotransferase activity. Plasma GST concentrations have been measured by radioimmunoassay in an open randomised study after halothane or isoflurane anaesthesia. The concentration of GST was significantly increased after anaesthesia in patients who received halothane in 30% oxygen/70% nitrous oxide (n = 37) and in patients who received halothane in 100% oxygen (n = 17). The frequency of abnormal GST concentrations, defined as 4 micrograms/l or more, was 35% and 24%, respectively. GST concentrations usually reached a peak 3-6 h after the end of anaesthesia. In 17 patients who received isoflurane in 30% oxygen/70% nitrous oxide, there was no significant rise in GST concentration and no patient had a concentration above 4 micrograms/l. No patient in any of the groups had a significant increase in alanine aminotransferase. In clinically identical situations, anaesthesia with halothane but not isoflurane leads to demonstrable impairment of hepatocellular integrity.

Adult↗
PubMed1986

Impaired hepatocellular integrity during general anaesthesia, as assessed by measurement of plasma glutathione S-transferase.

The measurement of plasma glutathione S-transferase (GST) concentrations have been used to assess the changes in hepatocellular integrity which occur following general anaesthesia. Of 20 selected patients, who received halothane for minor urological procedures, 16 showed a small transient rise in GST between 1 h and 3 h after anaesthesia. Similar changes were also observed in 8 consecutive patients who received halothane for various operative procedures. In 3 of these 28 patients a marked secondary rise in plasma GST was observed 24 h after anaesthesia. No significant changes in ALT were observed in either of the groups of patients. These data indicate two possible phases of hepatotoxicity following halothane administration which results in a transient impairment in hepatocellular integrity in the majority of patients who undergo anaesthesia with this agent.

Adult↗
PubMed1984

Contingent aftereffects in duration judgments.

It has been shown that judged duration of tones depends on pitch (the kappa effect), on order of presentation (the time-order error), and on repetition (a negative duration aftereffect). Recently, a duration aftereffect contingent on pitch and a duration aftereffect contingent on order of presentation have been described. Our results suggest that these contingent duration aftereffects differ from the McCollough effect, a color aftereffect contingent on orientation, in two ways. They have a relatively short life and they are not symmetrical, in that while a pitch-contingent duration aftereffect could be established, a duration-contingent pitch aftereffect could not. In contrast, the McCollough effect persists for days and both an orientation-contingent color aftereffect and a color-contingent orientation aftereffect have been reported. A decision theory account for contingent duration aftereffects is outlined.

Auditory Perception↗