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Biomedical subjects

E Marshall

Publications and source records attributed to E Marshall.

At least 469 records · Page 26Linked to original sources
PubMed1988

MRI of extremities using perforated single-turn solenoids.

A class of single-turn solenoids that permits magnetic imaging of the extremities in horizontal bore magnets with improved coupling between the imaged anatomy and the rf section of the imager is described and demonstrated. These devices differ from more conventional designs primarily by the placement of one or more access holes in the side of the generally cylindrical resonant structure to permit extremity insertion. The image quality is excellent, rf efficiency and homogeneity are good, and signal-to-noise is high, permitting rapid acquisition of magnetic images with small fields of view.

Extremities↗
PubMed1988

Hand preference in a normal population.

The Edinburgh Inventory was used to assess handedness in a normal population. The incidence of strong right-handedness increased with age and the incidence of left-handedness fell with age, both significantly. A non-significant increase in the incidence of left-handedness in twins was observed. The difference in the incidence of left-handedness for males and females failed to reach significance but more males were left-handed than females. Any difference in the incidence of left-handedness between the sexes must be small (less than 1.5%) and this has major theoretical implications.

Adolescent↗
PubMed1987

Morphological effects of chronic haloperidol administration on the postnatal development of the striatum.

The aim of this paper is to describe the morphological changes induced in the striatum after the administration of haloperidol during the first postnatal month, a period in which a lack of tolerance to treatment with neuroleptics has been reported. At the end of the treatment several morphological parameters were evaluated including neuron size and density and the synaptic profile areas of cross-sectioned dendrites and axon terminals. The results evidenced a loss of the smallest dendritic profiles without the rest of the parameters examined being affected. This response differs from the one observed in the adult rat striatum that does develop tolerance to haloperidol. It seems to more closely correspond to the changes found in the prefrontal cortex, a region that does not develop tolerance after chronic treatment with neuroleptics.

Animals↗
PubMed1987

Comparison of intestinal calcium absorption and circulating 1,25-dihydroxyvitamin D levels in malignancy-associated hypercalcaemia and primary hyperparathyroidism.

The relation between circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) levels and intestinal calcium absorption--as determined by an oral calcium load test--was studied in 16 patients with hypercalcaemia of malignancy (HM) and 16 with hypercalcaemic primary parathyroidism (HPT). In the HPT group serum calcium rose significantly after the oral calcium load and the increment correlated significantly with 1,25(OH)2D levels. While 1,25(OH)2D levels were raised to within the hyperparathyroid range in a number of HM patients, there was no correlation between change in serum calcium and 1,25(OH)2D level in the HM group and serum calcium did not rise significantly after the oral calcium load. HM patients with detectable or raised 1,25(OH)2D levels typically had few, or no, bone metastases in association with squamous lung cancers. A high proportion of these patients exhibited other aspects of hyperparathyroid-like activity such as increased renal tubular calcium reabsorption, depressed renal tubular phosphate reabsorption and elevated urinary cyclic AMP excretion. Conversely, HM patients with undetectable 1,25(OH)2D levels typically had extensive metastatic bone disease in association with breast carcinoma and were less likely to exhibit other hyperparathyroid-like features. It is postulated that in the former, the 'inappropriately' detectable or raised 1,25(OH)2D levels may have been due to enhanced renal 1 alpha-hydroxylase activity stimulated by the parathyroid hormone (PTH)-like effect of a non-PTH ectopic humoral mediator. In the latter the suppressed 1,25(OH)2D levels would be the predicted result of a non-humorally mediated hypercalcaemia. It is currently unclear why intestinal calcium absorption was depressed in all HM patients when 1,25(OH)2D levels were normal or raised in some cases. It is possible, however, that in HM there is 'end organ' resistance to the effects of 1,25(OH)2D due to a generalized malabsorptive process.

Calcium↗
PubMed1987

Raised thyrotrophin-releasing hormone, pyroglutamylamino peptidase, and proline endopeptidase are present in the spinal cord of wobbler mice but not in human motor neurone disease.

The Wobbler mouse (wr) is a mutant that exhibits loss of anterior horn cells in the spinal cord and brainstem and subsequent muscle wasting, particularly of the forelimbs and neck. The wr mice, 2-3 months of age, were found to have increased levels of immunoreactive-thyrotrophin-releasing hormone (ir-TRH) in the spinal cord and pons and medulla, but not in other CNS areas. This increase was observed in dorsal and ventral cord and at cervical, thoracic, and lumbar levels and was confirmed by HPLC to be authentic TRH. The levels of immunoreactive-somatostatin, -neurotensin, and -substance P were not raised in the CNS of wr mice. The activities of two peptidases capable of degrading TRH, pyroglutamylaminopeptidase (PGAP, EC 3.4.11.8) and proline endopeptidase (PEP, EC 3.4.21.26), and the level of 5-hydroxyindoleacetic acid were also raised in the spinal cord of 2-3-month-old wr mice although the activities of alanine aminopeptidase and lactate dehydrogenase and the level of 5-hydroxytryptamine were not. Increased spinal cord levels of ir-TRH and PGAP and PEP activities were not observed in the 1-month-old wr mice. In addition, a pilot study using spinal cord obtained at autopsy from three patients with motor neurone disease and 12 control subjects indicated no increase in spinal cord ir-TRH, PGAP, or PEP in human motor neurone disease.

Aminopeptidases↗
PubMed1987

Visual memory for pictorial stimuli in a serial choice reaction-time task.

Three experiments investigated the nature of the single-item visual recency effect in the serial choice reaction-time task (Rabbitt & Vyas, 1979; Walker & Marshall, 1982). The first experiment demonstrated that, like single letters varying in case, pictorial stimuli yield visual priming that is limited to consecutive stimuli and is unaffected by the presentation of an irrelevant stimulus in the response-stimulus interval. The second experiment confirmed that repeating a picture produces facilitation over and above repeating the object that it portrays. In addition, it was observed that name priming, but not visual or object priming, decreases with practice. This indicated that visual priming and object priming occur during identification. Finally, in Expt 3, an irrelevant picture was presented unpredictably in the response-stimulus interval. Previous results had suggested that this manipulation would provide evidence for distinct visual and object codes. Although the results were inconclusive, they do indicate that time intervals and presence of intervening information per se do not explain the loss of visual and object priming effects. It was suggested that the unpredictable irrelevant stimulus may have been disrupting a process whereby memory and perception interact directly at the level of a visual code.

Attention↗