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Biomedical subjects

S P Roberts

Publications and source records attributed to S P Roberts.

9 recordsLinked to original sources
PubMed1992

SK&F 104078, a post-junctionally selective alpha 2-adrenoceptor antagonist in the human saphenous vein in vitro.

The present study investigated the effects of SK&F 104078 (6-chloro-9-[(3-methyl-2-butenyl)oxy]-3-methyl-1H,2,3,4,- tetrahydro-3-benzazapine) at pre- and post-junctional alpha 2-adrenoceptors in the human isolated saphenous vein. Noradrenaline (0.001-100 mumol/l) produced concentration-dependent contractions of the human saphenous vein which were competitively antagonised by the alpha 1-adrenoceptor antagonist prazosin (0.01-1.0 mumol/l) and the alpha 2-adrenoceptor antagonist, rauwolscine (0.01-1.0 mumol/l), indicating the presence of both post-junctional alpha 1- and alpha 2-adrenoceptors in this preparation. The selective alpha 2-adrenoceptor agonist, UK-14,304 (0.01-100 mumol/l) also produced concentration-dependent contractions of the human saphenous vein which were antagonised by both rauwolscine (0.1 mumol/l) and prazosin (0.1 mumol/l). In the presence of angiotensin II (0.05 mumol/l), which itself produced a transient contraction, rauwolscine (0.1 mumol/l) produced a rightward shift of the UK-14,304 concentration-response curve while prazosin (0.1 mumol/l) had no effect. SK&F 104078 (10.0 mumol/l) under these conditions also produced a rightward shift of the concentration-response curve to UK-14,304, but was at least 100-fold less potent than rauwolscine. At pre-junctional alpha 2-adrenoceptors, exogenous noradrenaline (0.01 and 0.1 mumol/l) induced a concentration-dependent inhibition of stimulation-evoked [7-3H]-noradrenaline release from the human saphenous vein in vitro, which was antagonised by rauwolscine (0.1 mumol/l) and tolazoline (10.0 mumol/l) but not by SK&F 104078 (10.0 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists↗
PubMed1992

Central retinal vein occlusion in a middle-aged adult with HIV infection.

Recently central retinal vein occlusion (CRVO) has been described as a possible AIDS-related phenomenon. We have seen another case of CRVO in a middle-aged male with HIV infection. Extensive laboratory testing failed to reveal any other systemic abnormality which might be contributory. The potential role of HIV infection in the pathogenesis of CRVO is discussed.

Fluorescein Angiography↗
PubMed1992

Traumatic avulsion of the optic nerve.

Avulsion of the optic nerve is an infrequent traumatic event which results in a permanent and usually devastating loss of vision. We present two cases which highlight the salient features of partial and complete optic nerve avulsion. The clinical findings, including the results of B-scan ultrasonography, fluorescein angiography, and computed tomography (CT) are discussed. In addition, the past two decades of literature pertaining to optic nerve avulsion are reviewed and summarized.

Adult↗
PubMed1992

Malignant hyperpyrexia: a rare cause of postoperative death.

A middle aged man developed very high fever, status epilepticus, and terminal acute renal failure with myoglobinuria after surgery. A post mortem examination showed widespread muscle necrosis with hypercontraction bands. Muscle enzyme studies and electron microscopic examination disclosed central core disease, a condition closely related to malignant hyperpyrexia. This condition is a genetically inherited disorder which can be triggered by certain volatile anaesthetic agents or Suxamethonium. In this patient the condition may have been triggered by either the Isoflurane or the postoperative status epilepticus.

Humans↗
PubMed1992

Visual disorders of higher cortical function.

Following stroke or other causes of brain damage, patients may demonstrate visual disorders of higher cortical function. These defects involve visual attention, oculomotor skills, visuospatial orientation and object recognition. It is important for optometrists to understand these conditions and consider their presence in individuals with persistent visual complaints despite a normal exam, or in patients who fail to respond to magnification in low vision rehabilitation. The diagnosis and management of these higher order visual disturbances are discussed.

Agnosia↗
PubMed1991

Additional evidence for functional subclassification of alpha-2 adrenoceptors based on a new selective antagonist, SK&F 104856.

SK&F 104856 (2-vinyl-7-chloro-3,4,5,6-tetrahydro-4-methyl-thieno[4,3,2ef][3] benzazepine) shows a similar selectivity profile to the previously reported alpha adrenoceptor antagonist, SK&F 104078 (6-chloro-9-[(3-methyl-2-butenyl)oxy]-3-methyl-1H-2,3,4,5-tetrahydro-3- benzazepine), having the ability to block alpha-1 and postjunctional alpha-2 adrenoceptors, although having little or no activity at most prejunctional alpha-2 adrenoceptors. SK&F 104856 is more potent than SK&F 104078, and lacks the 5-hydroxytryptamine receptor antagonist activity associated with the earlier compound. The postjunctional vs. prejunctional selectivity of SK&F 104856 at alpha-2 adrenoceptors in the same tissue preparation was demonstrated in both canine and human saphenous vein. Concentrations substantially higher than those required to block postjunctional alpha-2 adrenoceptor-agonist induced vasoconstriction had no effect on the ability of norepinephrine, acting on prejunctional alpha-2 adrenoceptors, to inhibit stimulation evoked transmitter overflow in the human tissue, and only a small effect in the canine vein. As observed with SK&F 104078, SK&F 104856 has some prejunctional alpha-2 adrenoceptor antagonist activity in the rat vas deferens, although the receptor dissociation constant is nearly 50-fold higher than that at the postjunctional alpha-2 adrenoceptor in the canine saphenous vein. The results obtained with SK&F 104856 provide additional evidence to support the premise that alpha-2 adrenoceptors can be functionally differentiated. Because SK&F 104856 can selectively antagonize certain alpha-2 adrenoceptor-mediated responses, this agent may be a useful tool to evaluate the functional roles of the multiple alpha-2 adrenoceptor subtypes that have been identified in biochemical and molecular studies.

Adrenergic alpha-Agonists↗
PubMed1990

Back pain following general anaesthesia and surgery: evaluation of risk factors and the effect of an inflatable lumbar support.

Factors that contribute to postoperative lumbar back pain and the effect of an inflatable lumbar support on the incidence of postoperative backache were examined. The study consisted of two parts, a pilot study in which mathematical models for appropriate support pressures were produced and the main study to assess the role of an inflatable lumbar support. The use of a support reduced the incidence of back pain on the first postoperative day from 46 to 21 per cent (P = 0.007). The patient's sex, height, weight, and the presence or absence of obesity were not found to be significant factors in the incidence of postoperative back pain. Previous back pain or arthritis in any joint tended to be associated with an increase in the severity and incidence of postoperative back pain. Postoperative back pain was more severe after procedures lasting more than 40 min. Early mobilization reduced the amount of back pain. In conclusion, patients benefit from the use of an inflatable lumbar support if they have previously suffered from backache or if they are to be anaesthetized for more than 40 min.

Adult↗
PubMed1990

Meningitis after obstetric spinal anaesthesia.

A case of meningitis after obstetric spinal anaesthesia is reported. The possible aetiological causes of postspinal meningitis are discussed and the difficulty in differentiation between aseptic and bacterial meningitis noted. Ways to reduce the risk of bacterial contamination of cerebrospinal fluid are mentioned. The patient in this case made a full recovery, but the use of spinal anaesthesia in these patients is open to question.

Adult↗