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Biomedical subjects

J Elliott

Publications and source records attributed to J Elliott.

At least 199 records · Page 11Linked to original sources
PubMed1990

A cross-cultural cross validation of the Dental Fear Survey in South East Asia.

This study was designed as a cross-cultural replication and cross validation of the Dental Fear Survey (DFS) in two groups of Singapore adults: university students and military conscripts. Factor analysis of the DFS in each of these dissimilar samples revealed factor structures that were highly comparable to one another as well as to those obtained in the U.S.A. Behavioral and physiological fear assessment during exposure to simulated dental treatment also showed results comparable to those found in Western cultures. Self report measures were more likely to correlate with other self reports than with physiologic or behavioral measures. Among university students, those who had visited a dentist within the past year had significantly lower DFS scores than those who had avoided dentistry. The fear-avoidance relationship did not hold for military subjects who reported less dental fear overall. It was concluded that the DFS was factorially stable; and therefore, generalizable to this South East Asia culture.

Adolescent↗
PubMed1990

Prevalence of dental fear in young adult Singaporeans.

One-hundred-and-fifteen male military recruits and 176 mostly female first- and second-year students in the National University of Singapore were surveyed regarding their fear of the dentist. Nine of 115 recruits and 36 of 176 university students were classified as having high fear, giving a population prevalence rate between 78 and 208 fearful young adults per 1000 population. Higher educational levels were associated with fear of the dentist. There were no significant racial differences in the prevalence rate in either sample. Higher fear scores were associated with longer intervals between dental visits for the university but not the military population. Efforts are needed to prevent and ameliorate the development of dental fears. Trust and control appear to be major factors associated with dental fears.

Adolescent↗
PubMed1989

Complex lymphoid and epithelial thymic tumours in Thy1-myc transgenic mice.

T-lymphocyte development takes place mainly in the thymus, where stromal cells of epithelial and haemopoietic origin are involved in inductive and selective mechanisms, which enable specific lymphocyte populations to migrate to the periphery and establish a network of immune responses. Experiments with intact animals have clarified the precursor-product relationships between thymocyte subpopulations, but the molecular mechanisms of cell interactions in the thymus are difficult to study in vivo. In an attempt to expand thymic cell populations in vivo and maintain them in vitro for such studies, we directed high levels of expression of the murine c-myc proto-oncogene in transgenic mice by inserting it into the mouse Thy-1 transcriptional unit. Such mice develop thymic tumours which contain proliferating thymocytes and, interestingly, expanded populations of epithelial cells. Both cell types can be maintained in vitro.

Animals↗
PubMed1989

Semicarbazide-sensitive amine oxidase (SSAO) of the rat aorta. Interactions with some naturally occurring amines and their structural analogues.

The influence of a number of naturally occurring amines and their structural analogues has been examined on the metabolism of radiolabelled benzylamine (BZ) by the membrane bound semicarbazide-sensitive amine oxidase (SSAO) of the rat aorta. Only primary monoamines were effective in reducing the deamination of BZ. In the phenylethylamine series, addition of hydroxyl groups to the benzene ring decreased their potency as inhibitors while addition of a hydroxyl group at the beta position increased the inhibitory potency. Stereoselectivity of action was shown with octopamine, the L-isomer being the more active form. Kinetic analysis of these interactions showed predominantly competitive inhibition and kynuramine had the lowest Ki of 5.4 microM. The aliphatic monoamines, isoamylamine and isobutylamine both competed with BZ. 5-Hydroxytryptamine (5-HT) was the only amine that inhibited non-competitively. Direct evidence for metabolism by SSAO of some of the competing amines such as isoamylamine, phenylethylamine, tyramine and tryptamine was obtained by fluorimetric or radiochemical assays. The inhibitors clorgyline and (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine (MDL 72145) were used to characterise the amine oxidase activity responsible for the deamination. Octopamine and phenylethanolamine (PeOH) were not SSAO substrates and inhibited BZ metabolism in the fluorimetric assay. It is possible that the activity of SSAO is controlled by octopamine released from sympathetic nerve endings or 5-HT released from platelets.

Allosteric Regulation↗
PubMed1989

Metabolism of amines in the isolated perfused mesenteric arterial bed of the rat.

1. Semicarbazide-sensitive amine oxidase (SSAO) activity has been demonstrated in the isolated mesenteric arterial bed of the rat in vitro by studying the metabolism of benzylamine (Bz) and tyramine (Tyr) added to the perfusing fluid. 2. Pretreatment of rats with (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine (MDL72145), a potent inhibitor of SSAO in rat mesenteric blood vessels, reduced the amount of metabolites, following the addition of Bz (25 microM) or Tyr (100 microM) to the perfusing fluid, by 83% and 52% respectively. Inactivation of monoamine oxidase type A (MAO-A) by the addition of clorgyline (10 microM) to the perfusing fluid, had little effect on the appearance of metabolites from Tyr. 3. The presence of 3 microM cocaine in the perfusing fluid increased the amount of metabolites produced from Tyr. 4. The metabolites of Tyr appearing in the perfusion fluid from control preparations were 85% p-hydroxyphenylacetic and the remainder consisted of a mixture of p-hydroxyphenylacetaldehyde and, possible, p-hydroxyphenylethanol. 5. The metabolism of Tyr by homogenates of the rat mesenteric vascular bed was carried out by SSAO (60%) and MAO-A (40%) with very little contribution from MAO-B. Homogenates from rats pretreated with MDL 72145 showed metabolism of Tyr by MAO-A only. 6. These data indicate that SSAO is capable of metabolizing amines present in the fluid perfusing blood vessels to metabolites that are readily released. Histochemical evidence has shown that whereas MAO-A is present in the mitochondria of smooth muscle cells and nerve endings, SSAO is located in the plasma membrane of the smooth muscle cells. This subcellular distribution may explain the differences found between metabolites released from intact vessels and the metabolism seen in homogenates. The identity of the Tyr metabolizing activity in intact vessels that is resistant to both MDL 72145 and clorgyline remains to be determined.

Animals↗
PubMed1989

The influence of amine metabolizing enzymes on the pharmacology of tyramine in the isolated perfused mesenteric arterial bed of the rat.

1. The pressor response to the infusion of tyramine (Tyr) into the isolated perfused mesenteric arterial bed of the rat has been studied at both a low and a high dose (0.2 and 2.0 mumol) and the effect of monoamine oxidase-A (MAO-A) and semicarbazide-sensitive amine oxidase (SSAO) inhibition was examined. Very little MAO-B activity is found in homogenates of this tissue when Tyr is used as substrate. 2. Inhibition of SSAO by treating rats with 1 mg kg-1 (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroally lamine (MDL 72145) 1 h before dissection, had no significant effect on the maximum pressure attained or the area under the curve (AUC) of the response to both low and high doses of Tyr. Inhibition of MAO-A, by inclusion of 10 microM clorgyline in the perfusing fluid, resulted in no significant potentiation at both low or high doses of Tyr. The inhibition of both these enzymes together substantially increased the AUC of the pressor response. 3. Cocaine (3 microM) significantly potentiated the responses to adrenaline (Ad). At this dose, cocaine significantly reduced the peak height and the AUC of the responses to both doses of Tyr. 4. Inhibition of extraneuronal uptake mechanisms with corticosterone (29 microM) did not potentiate the response to Ad and did not significantly alter the response to Tyr (low dose). 5. The effects of MDL 72145 and clorgyline on the directly acting amine, Ad, were studied. MDL 72145 caused a small but significant increase in the EC50 and in the maximum response to Ad, whilst clorgyline (10 microM) increased the EC50 value slightly and decreased the maximum response.

Animals↗
PubMed1989

In-vivo effects of (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine (MDL 72145) on amine oxidase activities in the rat. Selective inhibition of semicarbazide-sensitive amine oxidase in vascular and brown adipose tissues.

One hour after MDL 72145 ((E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine) (2.5 mg kg-1) was given by intraperitoneal injection, the semicarbazide-sensitive amine oxidase (SSAO) activity of rat aorta and brown adipose tissue measured in-vitro was reduced by more than 95% of its control value, whereas the monoamine oxidase (MAO-A) activity remained virtually unaffected. The action of this drug on amine oxidases in the liver at this dose was less selective. The in-vitro effect of MDL 72145 on the soluble enzyme diamine oxidase from rat intestine was 100 fold less potent than that of semicarbazide but about equipotent with semicarbazide on sheep plasma amine oxidase. Overall MDL 72145 was selectively more active against membrane bound SSAO enzymes that deaminate primary monoamines. Although MDL 72145 does inhibit MAO-B activity these results suggest that this compound may be used to study the effect of selective inhibition of SSAO activity on the pharmacological responses of appropriate preparations in-vitro.

Adipose Tissue, Brown↗
PubMed1989

Neuropeptide Y in the sympathetic control of blood pressure in hypertensive subjects.

Neuropeptide Y (NPY) coexists with noradrenaline in postganglionic sympathetic neurons and with noradrenaline and adrenaline in the central nervous system. The possibility that NPY is released into the circulation during activation of the sympathoadrenal system was investigated in ten moderately hypertensive volunteers using three different stimuli. In healthy moderately hypertensive volunteers cold pressor test, head up tilt and graded bicycle exercise resulted in increased blood pressure, heart rate and plasma catecholamine concentrations. While there was a trend for plasma NPY-like immunoreactivity (NPY-LI) to increase during cold pressor test and head up tilt, NPY-LI concentration only increased significantly during bicycle exercise, the stimulus of greatest duration. These results suggest that plasma NPY-LI can be released into the circulation on sympathoadrenal activation in moderately hypertensive subjects and demonstrate that the pattern of release is similar to that previously observed in normotensive subjects.

Adrenal Glands↗
PubMed1988

Dialysis in the management of pregnant patients with renal insufficiency.

Successful pregnancy in patients on dialysis is uncommon because of a high rate of infertility and complications. The use of hemodialysis to manage pregnant patients needing dialysis has been well reported. However, to our knowledge, only 2 previous cases of pregnant patients using chronic ambulatory peritoneal dialysis (CAPD) have been reported. We discuss 14 pregnancies in 13 women in whom dialysis was used in the management of their pregnancies. Ten pregnancies were successful. Included are 5 successful pregnancies out of 8 managed with CAPD or chronic cycling peritoneal dialysis (CCPD). In comparing the cases managed with CAPD to those managed with hemodialysis, CAPD seems to offer several advantages. These include a more constant biochemical and extracellular environment for the fetus, higher hematocrit levels, infrequent episodes of hypotension, and no heparin requirement. In addition, intraperitoneal insulin facilitates the management of blood glucose in diabetics, and intraperitoneal magnesium facilitates the management of premature labor. Infection, loss of intraperitoneal volume, and loss of peritoneal clearances for solutes and water were not found to be problems.

Adult↗
PubMed1988

Cefotaxime plus metronidazole appears more effective than piperacillin in the prevention of postappendicectomy wound sepsis. Preliminary results of a comparative trial.

Metronidazole suppositories have previously been shown to be superior to povidone iodine intraoperative wound spray in reducing postappendicectomy wound sepsis. In subsequent studies metronidazole suppositories and cefotaxime injections reduced the sepsis rate to 9.3%, while the same combination produced a wound sepsis rate of 7.6% compared with 17.2% for cefotaxime alone. In an ongoing study, metronidazole and cefotaxime are now being compared with piperacillin in a single-blind trial. Adult patients undergoing emergency appendicectomy in Nottingham have been included in this study, which has ethical committee approval. When the decision to perform emergency appendicectomy was made, the patient was randomly allocated a numbered pack. This contained either 3 x 1g injections of cefotaxime and 6 x 1g metronidazole suppositories or 3 x 2g injections of piperacillin and 6 placebos. 40 minutes before operation the patient received the first suppository and the remainder every 8 hours. The patient received the first injection of antibiotic by intravenous or intramuscular injection and the remaining doses 8 and 16 hours later. A wound was regarded as infected if pus discharged either spontaneously or on incision. 175 patients have been studied to date. The treatment groups were well matched for age and sex. Seven of the 77 patients in the cefotaxime/metronidazole group (9.1%) compared with 12 of the 76 in the piperacillin group (15.8%) have developed wound infections. This study confirms that the combination of cefotaxime and metronidazole seems to be more effective than piperacillin alone in the reduction of postappendicectomy wound sepsis. Currently cefotaxime plus metronidazole is the therapy of choice.

Administration, Rectal↗
PubMed1987

Direct radioimmunoassay of human plasma atrial natriuretic peptide in various normal and pathophysiological states: increase in renal and cardiac failure during exercise.

We have used a sensitive direct radioimmunoassay to study the effects of exercise on plasma atrial natriuretic peptide (ANP) concentrations in man. Plasma ANP concentration increased three-fold in sixteen patients undergoing bicycle ergometer electrocardiographic tests for the investigation of chest pain. Resting ANP concentrations were higher in those patients in whom there was more evidence of heart disease, such as a positive exercise test, treatment with a beta blocker or history of myocardial infarction, although exercise resulted in increased ANP in both groups. We also confirm the increased plasma ANP concentration observed in patients with congestive cardiac failure and renal failure. In nine patients with renal failure routine haemodialysis was accompanied by a 30 per cent reduction in plasma ANP concentration. Plasma ANP concentrations were similar in treated hypertensive patients, untreated borderline hypertensive patients and normotensive subjects.

Adult↗