Search PubMed⌕ Search

Biomedical subjects

R Shields

Publications and source records attributed to R Shields.

At least 37 records · Page 2Linked to original sources
PubMed1990

The current cost of nuclear medicine.

In the light of the control of expenditure and changes in radiopharmaceutical costs, changes in study protocols, new investigation procedures and inappropriate placing in Korner categories, the BNMS Council set up a working party to derive an agreed set of costings for Nuclear Medicine techniques. Using data from three hospitals with additional information from another nine, we have agreed the 1988 cost of individual nuclear medicine procedures in the UK. These figures include staffing (radiopharmacy, nursing, physics, medical including consultant), radiopharmaceuticals and other consumables, indirect costs (secretarial, administrative, portering), variable overheads (service contracts, stationery) and fixed overheads (rates, lighting, heating, building and engineering). Capital costs, equipment and buildings were not included. Because figures include salary and overhead costs they are difficult to compare with the majority of other previous nuclear medicine costings, apart from Bretland et al., or with data for other imaging modalities. Comparison of these costings with Korner schedules shows marked overlap between the Korner groups. Such groups therefore form a poor method of costing nuclear medicine procedures. We propose alternative groupings.

Costs and Cost Analysis↗
PubMed1989

Variceal haemorrhage after failed injection sclerotherapy: the role of emergency oesophageal transection.

In a planned sequential policy for the emergency control of continued bleeding from oesophageal varices, oesophageal transection was performed after failure of conservative treatment, including injection sclerotherapy. In 15 patients who underwent emergency oesophageal transection, bleeding was controlled by operation in the majority (87 per cent), but 11 of the 15 patients died in hospital. Mortality in patients with poor liver function (Child's C) was 100 per cent, the majority of deaths resulting from hepatic and renal failure. The results of this study suggest that emergency oesophageal transection to control acute variceal haemorrhage is associated with a poor prognosis in patients with poor liver function and questions its role in a sequential emergency treatment policy.

Adult↗
PubMed1987

Functional competency of T cell antigen receptors in human thymus.

The T cell antigen receptor is likely to play a role in both positive and negative selection in the thymus. Three populations of thymocytes can be distinguished by the level of expression of the CD3-alpha/beta-chain heterodimer of the T cell antigen receptor (CD3/Ti alpha/beta) complex. Cells which fail to express these receptors or express low levels of receptors are contained in a population of thymocytes which express low levels of the CD5 antigen and are predominantly CD4+/CD8+. Thus, these cells appear to be relatively immature phenotypically. In contrast, the cells which express high levels of CD3/Ti alpha/beta co-express high levels of CD5 and are predominantly contained in the more mature single positive cells which express either CD4 or CD8. With the calcium-sensitive dye, Indo-1, and immunofluorescence, we demonstrated that, despite the relative phenotypic immaturity of cells which express low levels of CD3/Ti alpha/beta, these antigen receptors are able to mediate transmembrane signaling when stimulated with CD3 monoclonal antibodies. Although increases in calcium were observed in these CD3/Ti alpha/beta-low expressing cells in response to anti-CD3, no proliferative response was observed, even in the presence of phorbol myristate acetate. Proliferative responses were observed in the more mature cells which express high levels of CD3/Ti alpha/beta. These results suggest that, rather than a defect in the functional capability of the antigen receptor complex to mediate transmembrane signaling events, cellular responses to signals generated by the antigen receptor may differ at various stages of thymocyte development.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Ligand-receptor interactions required for commitment to the activation of the interleukin 2 gene.

Concanavalin A (Con A), which together with phorbol myristate acetate (PMA) can activate the human T cell line Jurkat to produce interleukin 2 (IL 2), is shown to depend on the expression of the T3/T cell antigen receptor heterodimer (T3/Ti) complex to induce activation. alpha-methyl mannoside was able to reverse all of the observed effects of Con A on intracellular biochemical events. Therefore, ligand-receptor occupancy appears to be required for sustaining biochemical events associated with triggering the T3/Ti complex. Studies of the time-dependent requirements for the two stimuli required for activation revealed that simultaneous stimulation with both Con A and PMA is required for 2 to 4 hr for the cell to commit itself to activation, as measured by the appearance of secreted IL 2. This 2- to 4-hr requirement correlated precisely with the appearance of IL 2 mRNA, and the appearance of IL 2 transcripts depended on protein synthesis during this critical time period.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Celiprolol versus timolol and placebo: a two week double-blind comparison.

Celiprolol (5%) was compared to timolol (0.5%) and placebo in patients with primary open angle glaucoma or ocular hypertension. A total of 28 patients participated in this double blind study and received treatment for two weeks. Intraocular pressure decreased an average of 4.4 mmHg with celiprolol and 7.1 mmHg with timolol two hours after instillation. This was maintained 12 hours after administration of timolol but not after celiprolol. There was a small but statistically significant decrease in pulse rate 2 hours after administration of timolol (from 72 to 64 beats per minute) which was not observed after celiprolol. Side effects were mild and similar for all 3 groups.

Adrenergic beta-Antagonists↗
PubMed1987

Relationship between gastric emptying of a solid meal and emptying of the gall bladder before and after vagotomy.

Little is known of the temporal and quantitative relationships between emptying of the stomach and of the gall bladder in patients with duodenal ulcer before and after vagotomy. A non-invasive double isotope technique was used to investigate these relationships in 27 patients with a duodenal ulcer, before and after operation-truncal vagotomy and pyloroplasty (TV + P; n = 15) and highly selective vagotomy (HSV; n = 12). A further 25 patients were studied after operation (TV + P, n = 20: HSV, n = 5). 99Tcm-EHIDA was used as the biliary tracer and 113Inm bran as the gastric content tracer. In patients with a duodenal ulcer before surgery and in 16 of the 17 patients studied after HSV, the patterns of gall bladder emptying were similar to those previously found in normal subjects. In 60% of patients after TV + P, patterns of gall bladder emptying were altered and the onset of gall bladder emptying was significantly delayed (p less than 0.001) compared with unoperated patients and patients with a HSV. The rate of gall bladder emptying did not correlate with the rate of gastric emptying in any of the patients studied. These observations suggest that TV + P, but not HSV, causes considerable alteration in coordination of gall bladder and gastric emptying.

Duodenal Ulcer↗
PubMed1987

Congenital vascular abnormalities in Okihiro's syndrome--a case report.

In this report, the authors describe the angiographic findings in the forearm and hand in Okihiro's syndrome. To the best of their knowledge, it has not been described before. Okihiro et al described hypoplasia of the thenar eminence in association with a congenital disorder of ocular motility previously reported in Duane's syndrome.

Adult↗
PubMed1987

SMS 201-995 and variceal haemorrhage.

Sandostatin (SMS 201-995) was evaluated in the treatment of variceal bleeding in 9 patients with liver cirrhosis and portal hypertension who were undergoing injection sclerotherapy following a variceal haemorrhage. SMS 201-995 reduced directly recorded intravariceal pressure by 38%, whereas reductions in the wedged hepatic venous pressure were around 17%. These observations suggest that SMS 201-995 may prove useful in treating bleeding oesophageal varices in the acute situation. Preliminary, promising data are shown in the results of a randomized controlled clinical trial in which SMS 201-995 plus injection sclerotherapy vs injection sclerotherapy are compared in patients with bleeding oesophageal varices. Furthermore, in experimental work associated stimulating effects of SMS 201-995 are shown on the function of the reticulo-endothelial system both in the liver and peripherally. These effects may prove useful by reducing the effects of endotoxaemia and possibly result in arresting further liver damage.

Animals↗
PubMed1986

A comparison of the effects of end-to-side portacaval shunting and side-to-side mesocaval shunting on hepatic haemodynamics in the dog.

Functional liver blood flow and hepatic artery flow were measured before and after either end-to-side portacaval or side-to-side mesocaval shunting in dogs. Functional liver blood fell by approximately 50% following both portacaval and mesocaval shunting. The hepatic artery response was variable after both portacaval and mesocaval shunts. It is concluded that side-to-side mesocaval shunts do not preserve hepatic blood flow or produce a greater compensatory increase in hepatic artery flow than conventional portacaval shunts.

Animals↗
PubMed1986

Effects of total and selective portasystemic shunting on hepatic haemodynamics and some aspects of liver function in the cirrhotic rat.

The effects of total and selective portasystemic shunting on hepatic haemodynamics and some aspects of liver function were studied in rats with dimethylnitrosamine-induced cirrhosis. Immediately following end-to-side portacaval shunting there were significant reductions in wedged hepatic venous pressure (WHVP) and liver blood flow. After side-to-side mesocaval shunting liver blood flow and wedged hepatic venous flow fell by approximately the same magnitude. Selective shunting (mesocaval 'H'-grafts and splenopancreaticocaval) preserved liver blood flow to a greater extent than total portasystemic shunting but had a less marked effect on WHVP. Furthermore, selective portasystemic shunting prevented liver atrophy and deterioration in liver function which was observed in rats following total portasystemic shunting. These results suggest that in the cirrhotic rat, selective portasystemic shunts which preserve functional liver blood flow and prevent liver atrophy and a deterioration in liver function do not produce such a marked decrease in WHVP as total shunts. Further studies in man are required to evaluate the relative advantages of total and selective portasystemic shunts.

Animals↗
PubMed1986

The effects of arterialisation of the portal stump on liver function and hepatic haemodynamics in cirrhotic rats with a portacaval shunt.

Liver blood flow (xenon-133 clearance method) and wedged hepatic venous pressure were studied in cirrhotic rats immediately after and 3 weeks following portacaval shunting (PCS), PCS and arterialisation of the portal stump with the left gastric artery (PCS-ART) or sham operation. Liver weight and function were compared 3 weeks after operation. Liver blood flow and wedged hepatic venous pressure were significantly reduced immediately after and 3 weeks following PCS. PCS-ART maintained liver blood flow and wedged hepatic venous pressure within the pre-operative range and prevented the liver atrophy and deterioration in liver function observed in rats with PCS. The results suggest that arterialisation of the portal vein with an artery which does not significantly increase sinusoidal pressure may be of benefit in preventing the early undersirable sequelae of PCS in man.

Animals↗
PubMed1986

Effects of somatostatin on hepatic haemodynamics in the cirrhotic rat.

Reports on the effects of somatostatin on hepatic haemodynamics in the cirrhotic patient have provided conflicting results. Therefore, we studied the effects of different modes and rates of somatostatin administration on hepatic haemodynamics in the cirrhotic rat. Portal pressure (PP), wedged hepatic venous pressure (WHVP), portal venous flow (PVF), liver blood flow (LBF) and systemic blood pressure were measured in rats with dimethylnitrosamine-induced cirrhosis. Somatostatin was administered as a rapid injection, a continuous infusion or as a bolus dose followed by a constant infusion. One group of rats with a previously constructed portacaval shunt received a bolus dose of somatostatin followed by a constant infusion. A rapid injection of somatostatin was attended by a rapid and significant fall in all the haemodynamic parameters measured (p less than 0.01). Continuous infusion of somatostatin [4 or 8 micrograms/kg body weight (BW) h] resulted in a gradual but significant reduction in PP, WHVP, PVF and LBF (p less than 0.05), but had no effect on systemic blood pressure. A bolus dose of somatostatin (2, 4 or 8 micrograms/kg BW over 2 min) resulted in a rapid decrease in PP, WHVP, PVF and LBF (p less than 0.01), the decreases being maintained by continuous infusion. In rats with a portacaval shunt a bolus dose of somatostatin (8 micrograms/kg BW) resulted in a rapid fall in WHVP and LBF, the decrease being maintained by a continuous infusion (8 micrograms/kg BW/h).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effects of alcohol on hepatic haemodynamics in the rat.

The effects of varying rates of alcohol infusion (0.015-0.12 mg/g body weight/min) on hepatic haemodynamics were studied in male Wistar rats. An infusion of 0.015 mg/g body weight/min alcohol had no significant effect on portal pressure (PP) or wedged hepatic venous pressure (WHVP). However, increasing rates of infusion of alcohol (0.03-0.12 mg/g body weight/min) progressively increased PP and WHVP, the maximum increase in PP occurring following an infusion of 0.12 mg/g body weight/min (6.5 +/- 0.5 - 10.3 +/- 0.6 mm Hg). The effect of varying rates of alcohol infusion on portal venous flow and liver blood flow was biphasic. Thus following an infusion of 0.03 mg/g body weight/min alcohol, liver blood flow (40.6 +/- 4.9 - 54.3 +/- 5.8 ml/100 g/min) and portal venous flow (28.6 +/- 2.9 - 41.3 +/- 4.1 ml/min) were increased. However, following infusions of 0.06 and 0.12 mg/g body weight/min alcohol, liver blood flow and portal venous flow were decreased. The results suggest that previous conflicting reports on the effects of alcohol on hepatic haemodynamics may be related to the dose of alcohol administered.

Animals↗
PubMed1986

Limits to parathyroid imaging with thallium-201 confirmed by tissue uptake and phantom studies.

Correct location by 201TI imaging of 48 parathyroids in 35 patients was related to size; 25 out of 26 parathyroids of mass greater than 1.0 g were correctly located, none of ten parathyroids less than 0.3 g was correctly located. In seven patients previously imaged, 108 microCi (4.0 MBq) of 201TI was injected when the thyroid was first exposed surgically. Subsequently weighed and histologically confirmed samples of parathyroid, thyroid, and skeletal muscle were counted against a standard in a well counter. Thallium-201 uptake, as %/g, did not differ between hyperplastic and adenomatous parathyroids. Mean parathyroid uptake was 0.018%/g, thyroid 0.01%/g, muscle 0.0026%/g of administered dose. Lower limits for correct location lay between 0.006-0.0149% of administered dose and between 0.25-0.8 g. Studies using a 201TI phantom containing small aliquots of 201TI at higher concentrations suggested approximately 0.0075% of the usual patient imaging dose as a lower limit for correct location.

Adenoma↗