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Biomedical subjects

R Dickinson

Publications and source records attributed to R Dickinson.

17 recordsLinked to original sources
PubMed1992

Celiprolol.

Explore the source record for details and available documents.

Antihypertensive Agents↗
PubMed1992

Effects of temperature on the anaesthetic potency of halothane, enflurane and ethanol in Daphnia magna (Cladocera: Crustacea).

1. The effects of temperature on the anesthetic potencies of halothane, enflurane and ethanol have been studied in the water flea Daphnia magna. 2. In the absence of anaesthetics, decreasing temperature resulted in decreased activity by the daphnids. 3. Potencies in the gas phase decreased with increasing temperature for all of the anaesthetics, while aqueous potency decreased for halothane and enflurane but increased for ethanol. 4. Enthalpy calculations suggest that the observed potency changes for the inhalational anaesthetics cannot be accounted for in terms of changing solubility in lipid bilayers but most likely reflect more specific interactions with animal target sites.

Animals↗
PubMed1991

Nodal involvement in poorly differentiated breast cancer.

The degree of nodal involvement in a consecutive series of 400 patients with invasive ductal breast cancer is presented. A positive correlation was observed between the number of metastatic nodes identified and the number of axillary nodes examined for poorly but not moderately differentiated tumours. The relevance of this observation to breast cancer trials is discussed.

Adult↗
PubMed1991

Probing the molecular dimensions of general anaesthetic target sites in tadpoles (Xenopus laevis) and model systems using cycloalcohols.

1. The series of cycloalcohols C6, C7, C8 and C10 have been used to probe the molecular dimensions of a variety of general anaesthetic target sites. 2. The general anaesthetic EC50 concentrations of the cycloalcohols were determined for tadpoles (Xenopus laevis). All of the cycloalcohols tested were found to be potent general anaesthetics (on average EC50/Csat = 0.03). 3. The effects of the cycloalcohols on highly purified luciferase enzymes from fireflies (Photinus pyralis) and bacteria (Vibrio harveyi) were also investigated. Both enzymes were inhibited competitively, with the cycloalcohols competing with firefly luciferin for binding to the firefly enzyme and with n-decanal for binding to the bacterial enzyme. 4. The binding site on the firefly enzyme could accommodate two molecules of cycloalcohols C6 and C7 but only a single molecule of the larger cycloalcohols (C8 and C10), implying a volume of the binding site of about 250 cm3 mol-1. In contrast, the binding site on the bacterial luciferase could bind only a single cycloalcohol molecule between C6 and C10. 5. While all of the cycloalcohols were potent inhibitors of the firefly luciferase enzyme (on average EC50/Csat = 0.015), they were very weak inhibitors of the bacterial luciferase enzyme (on average EC50/Csat = 0.12). Since both enzymes bind long-chain aliphatic n-alcohols tightly, the differing affinities of the cycloalcohols for the two enzymes is probably a consequence of geometrical factors. 6. The cycloalcohols produced very small effects on lipid bilayers. At EC50 concentrations which produce general anaesthesia, lipid bilayer phase transitions were shifted, on average, by only 0.43 degrees C. 7. We conclude that the general anaesthetic effects of the cycloalcohols can most economically be explained by assuming that the cycloalcohols act at protein binding sites in the central nervous system. These target sites would have binding properties similar to those of the anaesthetic-binding site on firefly luciferase, but their average volume would be somewhat smaller than 250 cm3 mol -1.

Alcohols↗
PubMed1989

Sequential moderate-dose methotrexate and 5-fluorouracil in advanced gastric adenocarcinoma.

A total of 23 patients with advanced gastric adenocarcinoma were treated with a combination of moderate-dose methotrexate (MDMTX), 250 mg/m2 i.v., with folinic acid rescue and 5-fluorouracil (5-FU) 600 mg/m2 i.v. Therapy was given every 7 days for 4 courses and then at 14-day intervals. All patients were evaluable for response. No complete responses occurred, but five patients (22%) had partial remissions (95% confidence limit, 5%-39%). The median duration of remission was 6 months, with a median survival of 11 months amongst responding patients. In all, six patients (26%) had stable disease for a median period of 5 months. The overall median survival was 6 months. Therapy was generally well tolerated, with principal toxicities consisting of neutropenia, nausea and vomiting, mucositis and diarrhoea. In terms of activity or survival in advanced gastric carcinoma, the combination of moderate-dose MTX and 5-FU does not appear to offer an advantage over single-agent therapy.

Adenocarcinoma↗
PubMed1989

An international survey of the educational activities of schools of pharmacy on psychoactive drugs.

A survey of the educational activities of schools of pharmacy on psychoactive drugs in 92 countries was carried out. All the schools which replied felt that there was a need for specific education on psychoactive drugs, and the majority felt that the rational use of such drugs should also be taught. Both the amount of teaching given and the methods used varied. This was particularly true for related subjects such as alternatives to psychoactive drug use. Almost a third of schools considered that they did not devote adequate time to psychoactive drugs and their rational use, and many would be grateful for specific educational guidelines in this area.

Curriculum↗
PubMed1988

Managing the dyspeptic patient: experience of a single-visit dyspepsia clinic.

During a one-year period, 206 of 245 patients referred directly to a single-visit dyspepsia clinic underwent gastroscopy after clinical consultation. Endoscopic findings enabled diagnosis in the majority and no complications occurred. In 12 patients with positive endoscopies there was an unrelated clinical diagnosis, and 23 with normal endoscopies had organic disease. Such a clinic has advantages both for patients in providing single-visit diagnosis and management for the majority, and for the hospital in reducing the load on outpatient services. Prior consultation may prevent both unwarranted use of endoscopy facilities and inappropriate diagnosis.

Adolescent↗
PubMed1985

Lipoxygenase products of arachidonic acid in human inflamed skin.

Monohydroxy acids (HETEs) and leukotriene B4 (LTB4) metabolites of arachidonic acid were measured in skin of healthy volunteers after ultraviolet B irradiation, and in the uninvolved skin of psoriatics after topical dithranol application. Exudate was collected from suction bullae on control and inflamed abdominal skin, and analysed for 12-HETE and PGE2 by GC-MS and LTB4 by bioassay. 12-HETE and PGE2 were raised at 24 h but not at 72 h after u.v.B irradiation: control and 24 h values were 13.7 and 41.5 ng ml-1 (P less than 0.05, n = 6) for 12-HETE respectively, and 4.5 and 30.2 ng ml-1 (P less than 0.01, n = 6) for PGE2. Dithranol application raised PGE2 levels from 23.1 ng ml-1 in control exudate to 62 ng ml-1 (P less than 0.01, n = 6) at 24 h before declining to base levels at 72 h. However, 12-HETE was raised at 72 h (200 ng ml-1, P less than 0.01, n = 5) but not at 24 h (104 ng ml-1) compared to control levels (50 ng ml-1, n = 5). The levels of the LTB4 were low (less than 100 pg ml-1), and no significant increases were observed. Arachidonic acid in inflamed skin can be metabolised by the cyclo-oxygenase and lipoxygenase pathway. It is probable that the lipoxygenase product 12-HETE is involved in these inflammatory reactions.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1976

The effect of trigeminal nerve and ganglion manipulation on recurrence of ocular herpes simplex in rabbits.

Latent herpes simplex virus (HSV) has been demonstrated in the trigeminal ganglia of experimentally infected rabbits between episodes of spontaneous ocular recurrence. In three experiments reported here, the normal pattern of recurrence was modified by manipulation of the trigeminal nerve and ganglion. Temporary retrobulbar disruption of trigeminal nerve function in chronically infected animals significantly decreased the number of ocular HSV isolations obtained during the 20 weeks immediately following surgery. Stereotaxic interruption of intracranial trigeminal nerve function prior to initial HSV infection dramatically reduced the incidence of peripheral recurrence of HSV. In chronically infected animals, stereotaxic stimulation of the trigeminal ganglion caused a marked increase in positive cultures within 2 days. These studies provide additional evidence for the theory that the reservoir for latent ocular HSV in rabbits is the trigeminal ganglion. Moreover, the studies suggest that the transmission of latent HSV from the trigeminal ganglion to its infectious form in the peripheral tissues involves the trigeminal nerve. We have shown that mechanical and stereotaxic stimulation of the trigeminal ganglion is a reliable and rapid means of precipitating peripheral ocular shedding of HSV on command, a finding which should prove most productive in future research.

Animals↗
PubMedDate not supplied

Experimental reactivation of ocular herpes simplex in rabbits.

Latent herpes simplex virus (HSV) is known to reside in the trigeminal ganglia. Our studies show that the temporary retrobulbar disruption of trigeminal nerve function in chronically infected animals caused a striking decrease in the number of positive HSV cultures obtained during the 20 weeks immediately following surgery. We found that the stereotaxic interruption of intracranial trigeminal nerve function prior to initial HSV infection dramatically reduced the incidence of peripheral recurrence of HSV. Stereotaxic stimulation of the trigeminal ganglion in chronically infected animals produced a significant increase in positive cultures within two days. But, direct neurosurgical stimulation of the trigeminal ganglion proved strikingly effective, producing 83% positive cultures at the eye within 48 hours of operation. These studies further substantiate the premise that the trigeminal ganglion serves as a reservoir for latent HSV from the trigeminal ganglion to its infectious form in the peripheral ocular tissues somehow involves the trigeminal nerve.

Animals↗