Biomedical subjects
Publications and source records attributed to J A Cross.
The presentation of atrioventricular block in the critical care setting and the assessment parameters that the critical care nurse may use to aid in the determination of the severity of atrioventricular block are described. The underlying pathophysiology of atrioventricular block is examined to enhance the nurse's understanding of the rationale for intervention versus observation.
Percutaneous cardiopulmonary bypass is a new technique for supporting systemic blood flow during high-risk coronary angioplasty procedures. This mechanical alternative, unlike traditional methods, is not limited by dependency on adequate left ventricular stroke volume. Percutaneous cardiopulmonary bypass support offers new and demanding challenges in the care of this high-risk group of patients.
Binding sites for gamma-aminobutyric acid, type B (GABAB), were measured in post-mortem brain samples (frontal cortex, temporal cortex, and hippocampus) from a group of suicide victims and a group of sex- and age-matched controls. Retrospective psychiatric diagnosis was performed, and only suicide victims with clear evidence of depression in the absence of symptoms of other psychiatric or neurological disorders were studied. There were no significant differences between depressed suicides and controls in the number or affinity of GABAB binding sites in the frontal or temporal cortex and no difference in GABAB binding (measured at two concentrations) in the hippocampus. Thirteen of the depressed suicides had not been prescribed antidepressant drugs recently, and none were found in their blood at postmortem. The number of GABAB binding sites in the frontal and temporal cortex and GABAB binding in the hippocampus did not differ significantly between these drug-free suicides and matched controls. The Kd was higher, however, in the temporal cortex of the drug-free suicides than in the controls. A significant negative correlation was found between age and the number of GABAB binding sites in the temporal cortex (on the basis of pooled data from suicides and controls). These results indicate that GABAB binding sites are unaltered in the brains of depressed suicide victims.
1. The effects of chronic oral administration of desmethylimipramine (DMI) or zimelidine (1.25 and 5 mg kg-1 twice daily for 21 days) were studied on rat whole cortical gamma-aminobutyric acidB (GABAB) binding sites. No changes in receptor affinity or number were found with either drug. 2. A subsequent study of GABAB binding sites using higher doses of these drugs (5 and 10 mg kg-1) and rat frontal cortex was also without effect, when investigated 24 h after termination of drug administration or 72 h after DMI administration (5 mg kg-1). 3. The number of frontal cortical 5-hydroxytryptamine2 (5-HT2) binding sites was significantly and dose-dependently decreased after both drugs, whereas the number of hippocampal 5-HT2 binding sites was not significantly altered after either drug. 4. As the number of frontal cortical GABAB binding sites was unaltered whereas the number of 5-HT2 binding sites was significantly decreased under identical study conditions, it may be concluded that the effects of antidepressant administration upon GABAB binding sites is a less consistent observation than their effects on 5-HT2 binding sites.
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Desmethylimipramine and zimelidine (10 mg/kg) were administered to rats once daily for 21 days. Chronic desmethylimipramine significantly reduced the number of 5HT2 binding sites in the frontal cortex but not hippocampus while chronic zimelidine did not affect 5HT2 binding in either brain region. The number and affinity of GABAB binding sites in the frontal cortex were unaltered by either drug.
The neurochemical profile of the novel inhibitor of uptake of 5-hydroxytryptamine (5-HT) panuramine (Wy 26002) has been investigated in the rat. In vitro, panuramine was found to be a potent and selective inhibitor of uptake of 5-HT with an IC50 of 22 +/- 4 nM. The IC50 for inhibition of uptake of noradrenaline was 848 nM and that for uptake of dopamine greater than 10 micron. Panuramine, in concentrations up to 10 micron did not displace the specific binding of either [3H]spiroperidol or [3H]5-HT and had no effect on the spontaneous or potassium-evoked release of 5-HT, suggesting that the compound had little effect on serotonergic transmission other than the inhibition of uptake of 5-HT. Panuramine also produced a dose-related antagonism of the depletion of 5-HT in brain induced by p-chloroamphetamine, confirming the ability of the drug to inhibit uptake of 5-HT in vivo.
Thirty-five patients kept in a sitting position for 5 min after a standard extradural injection in labour were compared with 54 patients maintained in the left lateral position throughout. The mean upper limit of analgesia was unchanged. A significant shift of the mean lower limit occurred in the sitting patients (P = 0.05, two-tailed), but contrary to classical teaching this was in a cephalad direction. Successful sacral blockade (analgesia at S234) and asymmetry of blockade occurred in a similar proportion of each group. It was concluded that the sitting position conferred no clinical advantage to patients receiving extradural analgesia in labour.
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Explore the source record for details and available documents.