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Biomedical subjects

R E Coupland

Publications and source records attributed to R E Coupland.

At least 37 records · Page 2Linked to original sources
PubMed1986

Echo planar imaging of normal and abnormal connections of the heart and great arteries.

Echo planar imaging (EPI) is that form of magnetic resonance imaging which provides very short image acquisition times. EPI also provides very rapid sequential imaging. The EPI method is ideal for imaging the heart and thoracic content because images are devoid of cardio-respiratory motion artefact. Previously an analysis of transectional images has been presented. This paper is concerned with the study of the heart by the use of EPI constructions in the sagittal and coronal planes. Defining connections between ventricle and great artery is of cardinal importance in paediatric cardiology. EPI constructions in the normal heart, transposition, truncus arteriosus and right heart hypoplasia are presented and discussed.

Heart Defects, Congenital↗
PubMed1986

Transectional echo planar imaging of the heart in cyanotic congenital heart disease.

Echo planar imaging is that form of magnetic resonance imaging which gives very short image acquisition times. The method has been used to produce images of the infant heart which are free of cardiorespiratory motion artefact, despite tachypnoea and tachycardia. EPI transections of the normal heart are compared with transections in truncus arteriosus, tetralogy of Fallot, right heart hypoplasia and transposition of the great arteries. The diagnosis of the cause of cyanosis in these infants was established by the noninvasive EPI method and validation of the findings may be found in transectional postmortem analyses reported in the literature.

Heart Defects, Congenital↗
PubMed1986

Measurement of T1 by echo-planar imaging and the construction of computer-generated images.

The high-speed echo-planar imaging (EPI) technique is used to obtain rapid T1 and spin density measurements by a two-point method. It is shown that neglect of edge effects in the slice selection procedure leads to significant systematic errors in T1. T1 maps for two young patients, obtained at 4.0 MHz, are presented. The T1 and spin density values obtained are used to produce computer-generated images in inversion recovery simulations. These results demonstrate marked improvement in image contrast without paying the time penalty incurred in real experiments, thereby greatly increasing patient throughput potential.

Abdomen↗
PubMed1985

Immunohistochemical and biochemical study on the development of the noradrenaline- and adrenaline-storing cells of the adrenal medulla of the rat.

The pre- and postnatal development of the adrenal medulla was examined in the rat by immunohistochemistry and by assay of catecholamines. Immunohistochemistry involved the use of antibodies to noradrenaline (NA), adrenaline (A) and the biosynthesizing enzymes dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT). Adrenal glands were obtained from animals from the 16th day of gestation to the 7th postnatal day at daily intervals, and at the 14th postnatal day, and from adult rats. Tissues were fixed in ice-cold, 4% paraformaldehyde, buffered at pH 7.3. Cryostat sections (7 microns) were stained with the indirect immunofluorescence technique. Adrenals from the same developmental stages were assayed for the presence of DA (dopamine), NA and A by ion-pair reversed-phase liquid chromatography with electrochemical detection. In adult adrenals the majority of the medullary cells (approximately 80%) were highly immunoreactive to A and moderately immunoreactive to NA. They also showed immunoreactivity to both DBH and PNMT, i.e., they are synthesizing and storing A. The remaining cell clusters were only stained by antibodies to DBH and NA (NA-synthesizing and -storing cells). These findings correlate well with the relative concentrations of A and NA as determined by assay. Three developmental phases could be distinguished. In the first phase, the 16th and 17th prenatal day, medullary cells were only immunoreactive to DBH and NA, and only very small amounts of A as compared to NA were found. During the second period, from the 18th prenatal day to 2 or 3 days after birth, all medullary cells were immunoreactive to DBH, NA, PNMT and A, and during this phase the adrenaline concentration increased daily and became the predominant amine on the 20th day of gestation. Adrenaline represented 75% of total catecholamine on the 1st to 3rd day after birth. The third phase started at the 2nd or 3rd postnatal day and was characterized by the presence of an increasing number of medullary cells solely immunoreactive to DBH and NA, hence synthesizing and storing NA. The remaining cells were immunoreactive to DBH, NA, PNMT and A. Postnatally, the relative concentration of A continued to rise reaching 79% by the 4th postnatal day. These results indicate that initially the adrenal medullary cells are synthesizing and storing almost exclusively NA.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Medulla↗
PubMed1985

The effect of in vivo hydrocortisone administration on the labelling index and size of the intra- and extra-adrenal chromaffin tissue of the fetal and perinatal mouse.

Administration of hydrocortisone in vivo to pregnant mice between the eighth and sixteenth days of gestation leads to highly significant increases in both the volume and the labelling index of extra-adrenal chromaffin tissue (as represented by the para-aortic body) of 16 days fetal mice. The labelling index of intra-adrenal chromaffin cells increases slightly after hydrocortisone administration, but the volume of the adrenal chromaffin tissue was not assessed since the groups of chromaffin cells had not in all cases aggregated to form a distinct medulla. Hydrocortisone administration to mice for the last week of gestation also leads to a highly significant increase in the size and the labelling index of the perinatal para-aortic body. Although an increase in the labelling index of perinatal intra-adrenal chromaffin cells is brought about, this is much less marked than that of the extra-adrenal tissue and neither is it reflected by any increase in the volume of the now discernible adrenal medulla. These increases in size and labelling index of the para-aortic body constitute a hyperplastic response rather than a hypertrophic response. Various possible mechanisms and implications are discussed in the light of the development of chromaffin tissue and the effects of the cortex and its secretions on the medulla. Associated effects of hydrocortisone noted in this work are the resultant marked diminution of adrenocortical volume in the perinatal gland, and a slight fall in the labelling index of perinatal intra-adrenal haemopoietic cells.

Adrenal Glands↗
PubMed1984

On the uptake and storage of 5-hydroxytryptamine, 5-hydroxytryptophan and catecholamines by adrenal chromaffin cells and nerve endings.

Light-microscopic autoradiographs of the adrenal medulla at various intervals after the intravenous injection of [3H] 5-HTP, [3H] 5-HT, [3H] noradrenaline and [3H] adrenaline have been studied. The distribution of silver grains following [3H] 5-HTP uptake was found to be uniform over each of the two main cell populations, adrenaline-storing (A) cells and noradrenaline-storing (NA) cells in the adrenal medulla, but A cells were twice as active as NA cells in incorporating the isotope, a situation very similar to that found after [3H] dopa uptake. 5-HT administration resulted in a pattern resembling the distribution of [3H] noradrenaline uptake, with A cells being 4 or 5 times more active than NA cells and a gradient of activity from the periphery of the medulla inwards. However, the time-course for the loss of radioactivity was not the same for both amines: levels of 5-HT activity were not significantly reduced after one week whereas the degree of [3H] noradrenaline labelling after one week was less than 10% of that at one hour. Thus 5-HT may be bound to sites in the adrenal medulla normally occupied by noradrenaline but it would appear that the release mechanism is different. There was no evidence of 5-HT uptake by adrenal nerve endings.

5-Hydroxytryptophan↗
PubMed1984

Effects of hypophysectomy and metyrapone on the catecholamine content and volumes of adrenaline- and noradrenaline-storing cells in the rat adrenal medulla.

Using morphometric analysis and high-pressure liquid chromatography with electrochemical detection of catecholamines the volumes of adrenaline-storing (A) and noradrenaline-storing (NA) cells and the adrenaline and noradrenaline contents of adrenal glands of normal and age-matched hypophysectomized rats were determined and compared. Some hypophysectomized rats were also administered 150 mg metyrapone/kg daily for a 4-week period. Hypophysectomy resulted in an increase in noradrenaline storage in adrenal glands. This was more marked in hypophysectomized animals not treated with metyrapone even though the combination of metyrapone and hypophysectomy resulted in a reduction of blood corticosterone concentration to only approximately 6% normal. There was no evidence of a change in proportion of A and NA cells in the adrenal medulla of hypophysectomized rats or hypophysectomized animals treated with metyrapone and it is concluded that the changes in amine concentrations and proportions observed reflect an increase in the storage of noradrenaline in A cells as a consequence of less efficient methylation of noradrenaline after hypophysectomy. The findings also showed that the left adrenal gland and medulla was usually slightly larger and had a greater catecholamine content and slightly higher proportion of NA cells than the right adrenal gland. During the period of the experiment (animals aged 6-15 weeks) there was an increase in the concentration of both adrenaline and noradrenaline in the normal adrenal glands. In normal Sprague-Dawley rats weighing 140 and 400 g the adrenal medulla accounted for some 5% of adrenal volume; this increased to 13% after hypophysectomy; A and NA cells together accounted for 50-60% of the volume of adrenal medulla.

Adrenal Medulla↗
PubMed1983

Real-time nuclear magnetic resonance clinical imaging in paediatrics.

Echo-planar imaging (EPI), a distinctive variant of nuclear magnetic resonance, needs only a fraction of a second for an image to be acquired and so is free from movement artifacts caused by respiration or heart beat. Clinical findings in the lungs, heart, and mediastinum of three children with high respiratory and heart rates who were examined by EPI are described.

Bronchopulmonary Dysplasia↗
PubMed1983

Dynamic NMR cardiac imaging in a piglet.

NMR echo-planar imaging (EPI) has been used in a realtime mode to visualise the thorax of a live piglet. Moving pictures are available on an immediate image display system which demonstrates dynamic cardiac function. Frame rates vary from one per cardiac cycle in a prospective stroboscopic mode with immediate visual output to a maximum of 10 frames per second yielding up to six looks in one piglet heart cycle, but using a visual playback mode. A completely new system has been used to obtain these images, features of which include a probe assembly with 22 cm access and an AP400 array processor for real-time data processing.

Animals↗
PubMed1982

Normal function of extra-adrenal chromaffin tissues in the young rabbit and guinea-pig.

An attempt has been made to determine the relative functional activities of adrenal and extra-adrenal chromaffin tissue during the neonatal phase and up to 1 week of age using young rabbits and guinea-pigs whose main extra-adrenal abdominal para-aortic chromaffin bodies are respectively non-innervated and innervated. Amine synthesis and storage were followed by assay and autoradiography after a single intraperitoneal injection of L-[2,5,6-3H]DOPA and the findings correlated with amine content as assessed by high performance liquid chromatography and by volume of tissue. The results indicate that in the guinea-pig, in spite of differences in proportions of adrenaline and noradrenaline in the adrenal gland and para-aortic body (PAB), the loss of labelled catecholamines from the innervated PAB closely follows that from the adrenal medulla, suggesting that both participate in normal sympathoadrenal activity. By comparison, in the rabbit the PAB shows only a minimal decreased labelled amine during the first week of life during which period the amine content and concentration of the PAB doubles: the functional significance of this non-innervated extra-adrenal chromaffin tissue, which persists throughout life, has still to be determined.

Adrenal Cortex↗
PubMed1981

On the uptake of exogenous catecholamines by adrenal chromaffin cells and nerve endings.

Light-microscopic autoradiography has revealed characteristic labelling patterns in adrenal medullary cells following the intravenous administration of different catecholamines. The uptake patterns for [3H] dopa, [3H] dopamine, [3H] noradrenaline and [3H] adrenaline ahve been compared. In all cases A cells were more active than NA cells and cells situated in the zone nearest the cortex demonstrated a markedly higher rate of uptake than central cells. It was concluded that adjacent chromaffin cells with very similar morphology may differ as much as 50 fold in their capacities to incorporate exogenous amines. The adrenergic nature of te innervation of the vessels of the adrenal cortex and capsule in the mouse was confirmed.

Adrenal Medulla↗
PubMed1981

Effect of hydrocortisone, reserpine, propranolol and phentolamine on in vivo uptake of exogenous amines by adrenal chromaffin cells.

An autoradiographic study was performed on the effects of hydrocortisone, reserpine, propranolol and phentolamine on the uptake of tritiated amines by adrenal medullary cells of the mouse. Oral feeding of hydrocortisone ahd no significant effect on the normal uptake pattern of dopamine, noradrenaline or adrenaline by medullary cells of different type (A cells or NA cells) or location (marginal or central), although the overall amounts taken up were markedly reduced. Handling the animals led to similar reductions in the uptake of all three amines and was thus clearly shown to be the important factor in this effect. Reserpine reduced the uptake of [3H] noradrenaline to 25% of the control value although the relative distribution remained unchanged. Propranolol and phentolamine had no observed effect on [3H] noradrenaline uptake. These results are discussed in the light of the previously reported action of ACTH in reversing the effects of hypophysectomy on medullary amine uptake (Hirano and Kobayashi 1978), and it is concluded that ACTH must exert this effect directly on the adrenal medulla rather than through the secretion of adrenal corticosteroids. It is also suggested that reserpine acts, as in neurons, by blocking amine uptake into intracellular granules rather than by blocking uptake into the cell itself.

Adrenal Medulla↗
PubMed1980

Human whole body imaging and detection of breast tumours by n.m.r.

A brief review of recent developments in line scan imaging of large objects is given, together with some representative images showing anatomical detail and a discussion of some spin-lattice relaxation time mapping results. Current progress in high speed imaging by means of the echo planar technique is reported and some preliminary results obtained at both 15.0 and 4.0 MHz are discussed.

Breast Neoplasms↗