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Biomedical subjects

T J Turner

Publications and source records attributed to T J Turner.

9 recordsLinked to original sources
PubMed1992

Calcium channels coupled to glutamate release identified by omega-Aga-IVA.

Presynaptic calcium channels are crucial elements of neuronal excitation-secretion coupling. In mammalian brain, they have been difficult to characterize because most presynaptic terminals are too small to probe with electrodes, and available pharmacological tools such as dihydropyridines and omega-conotoxin are largely ineffective. Subsecond measurements of synaptosomal glutamate release have now been used to assess presynaptic calcium channel activity in order to study the action of peptide toxins from the venom of the funnel web spider Agelenopsis aperta, which is known to inhibit dihydropyridine and omega-conotoxin-resistant neuronal calcium currents. A presynaptic calcium channel important in glutamate release is shown to be omega-Aga-IVA sensitive and omega-conotoxin resistant.

Agatoxins↗
PubMed1992

Basic emotions: can conflicting criteria converge?

The authors discuss some of the key points raised by Ekman (1992), Izard (1992), and Panksepp (1992) in their critiques of Ortony and Turner's (1990) suggestion that there are and probably can be no objective and generally acceptable criteria for what is to count as a basic emotion. A number of studies are discussed that are relevant to the authors' contention that a more promising approach to understanding the huge diversity among emotions is to think in terms of emotions being assemblages of basic components rather than combinations of other basic emotions. The authors stress that their position does not deny that emotions are based on "hardwired" biological systems. On the other hand, the existence of such systems does not mean that some emotions (such as those that appear on lists of basic emotions) have a special status. Finally, the authors note that Ekman, Izard, and Panksepp, in adopting different starting points for their research, arrive at rather different conclusions as to what basic emotions are and which emotions are basic. It is concluded that converging resolutions of these questions are improbable.

Arousal↗
PubMed1991

Calcium as a coagonist of inositol 1,4,5-trisphosphate-induced calcium release.

Inositol 1,4,5-trisphosphate (IP3)-induced calcium release from intracellular stores is a regulator of cytosolic-free calcium levels. The subsecond kinetics and regulation of IP3-induced calcium-45 release from synaptosome-derived microsomal vesicles were resolved by rapid superfusion. Extravesicular calcium acted as a coagonist, potentiating the transient IP3-induced release of calcium-45. Thus, rapid elevation of cytosolic calcium levels may trigger IP3-induced calcium release in vivo. Extravesicular calcium also produced a more slowly developing, reversible inhibition of IP3-induced calcium-45 release. Sequential positive and negative feedback regulation by calcium of IP3-induced calcium release may contribute to transients and oscillations of cytosolic-free calcium in vivo.

Adenosine Triphosphate↗
PubMed1991

Validation of the crisis triage rating scale for psychiatric emergencies.

Using a sample of 500 emergency psychiatric patients at Victoria Hospital in London, Ontario, this study replicated part of the research on the Crisis Triage Rating Scale (CTRS) conducted by Bengelsdorf, Levy, Emerson and Barile in 1984. The relationship between the suggested CTRS cut-off score and the decision whether or not to hospitalize the patient was studied, independently of these scores. The relative contribution of each of the subscales (Dangerousness, Support System and Ability to Cooperate) to this decision was also determined. The results of this study suggest that using a cut-off score of 9, the easily administered Crisis Triage Rating Scale could be an additional assessment aid in determining whether patients require emergency hospital admission to a psychiatric unit.

Activities of Daily Living↗
PubMed1991

Interleukin-1 augments gamma-aminobutyric acidA receptor function in brain.

Interleukin-1 (IL-1), a cytokine involved in the acute phase reaction to injury and infection, has multiple effects in the central nervous system, including induction of fever and sleep and the release of several neuropeptides. We evaluated effects of IL-1 beta on inhibitory postsynaptic function at the gamma-aminobutyric acidA (GABAA) receptor. IL-1 (100 pg/ml to 10 ng/ml) augmented GABAA receptor function in cortical synaptic preparations. This effect of IL-1 was largely prevented by incubation with a specific IL-1 receptor antagonist. The related cytokines interleukin-6 and tumor necrosis factor did not augment GABA-dependent chloride transport. Similar enhancement of GABAA receptor function was observed in tissue prepared from mice previously injected intraperitoneally with IL-1 (1 microgram). Electrophysiological studies in cultured primary cortical neurons demonstrated that IL-1 enhanced the GABA-mediated increase in chloride permeability, whereas IL-1 alone produced no alterations in resting conductance. Behavioral studies indicated that IL-1 is similarly active in vivo; mice treated with IL-1 showed a decrease in open-field activity and an increase in the threshold for pentylenetetrazol-induced seizures. The interaction of IL-1 with GABAA receptors might account for the somnogenic and motor-depressant effects of this cytokine.

Animals↗
PubMed1990

What's basic about basic emotions?

A widespread assumption in theories of emotion is that there exists a small set of basic emotions. From a biological perspective, this idea is manifested in the belief that there might be neurophysiological and anatomical substrates corresponding to the basic emotions. From a psychological perspective, basic emotions are often held to be the primitive building blocks of other, nonbasic emotions. The content of such claims is examined, and the results suggest that there is no coherent nontrivial notion of basic emotions as the elementary psychological primitives in terms of which other emotions can be explained. Thus, the view that there exist basic emotions out of which all other emotions are built, and in terms of which they can be explained, is questioned, raising the possibility that this position is an article of faith rather than an empirically or theoretically defensible basis for the conduct of emotion research. This suggests that perhaps the notion of basic emotions will not lead to significant progress in the field. An alternative approach to explaining the phenomena that appear to motivate the postulation of basic emotions is presented.

Biological Evolution↗
PubMed1976

Amylase: creatinine clearance ratio and urinary excretion of lysozyme in acute pancreatitis and acute duodenal perforation.

The amylase:creatinine clearance ratio in patients suffering from acute pancreatitis or acute duodenal perforation was higher than normal in both groups of patients. These findings cast doubt on the value of this parameter as a specific index of acute pancreatitis. The mechanism or mechanisms underlying the increased amylase excretion have not been determined. However, the markedly elevated urinary excretion of lysozyme observed in some patients suggests, by analogy, that diminished tubular reabsorption of amylase may contribute towards the elevated amylase:creatinine ratio.

Acute Disease↗