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Biomedical subjects

S Walton

Publications and source records attributed to S Walton.

At least 73 records · Page 4Linked to original sources
PubMed1992

Role of prostaglandins in delayed cerebral ischemia after subarachnoid hemorrhage.

Prostaglandin E2, thromboxane B2, and 6-oxo-prostaglandin F1 alpha were assayed in blood and cerebrospinal fluid samples from patients after subarachnoid hemorrhage (SAH) and from a control population. The levels found in samples obtained from patients after SAH were compared with those found in controls and were also correlated with a number of clinical and radiological variables, many of which are either significantly associated with or represent evidence of cerebral ischemia. The levels of prostaglandin E2, thromboxane B2, and 6-oxo-prostaglandin F1 alpha in blood samples from patients after SAH and from controls were below the level of sensitivity of the assays. Levels of prostaglandin E2, thromboxane B2, and 6-oxo-prostaglandin F1 alpha in cerebrospinal fluid from patients after SAH were significantly elevated when compared with those found in control samples. There was no significant correlation, however, between the level of each prostaglandin measured and the following variables: clinical grade on admission as assessed by the Glasgow Coma Score and the World Federation of Neurological Surgeons grading system; the amount of subarachnoid blood seen on computed tomographic scan; the occurrence of ischemic deterioration; the occurrence of low density change on computed tomographic scan; the presence of vasospasm on angiography; clinical outcome as assessed by the Glasgow Coma Score 3 months after the ictus; and the incidence of ischemia as a cause of death or disability as assessed 3 months after the ictus. A primary role for prostaglandins in the etiology of delayed cerebral ischemia after SAH is not therefore confirmed.

Brain Ischemia↗
PubMed1992

Does thrombin prevent cerebral vasospasm following aneurysmal subarachnoid haemorrhage?

Fibrinopeptide A (FPA) levels which have been shown to be a quantitative index of thrombin generation, were measured in blood and cerebrospinal fluid (CSF) samples from patients following subarachnoid haemorrhage (SAH) and from a control population. The levels found in samples obtained in patients following SAH are compared with those found in controls and also correlated with clinical grade on admission as assessed by the Glasgow Coma Score and the World Federation of Neurological Surgeons' grading system, and with the amount of subarachnoid blood seen on CT, the occurrence of ischaemic deterioration, the occurrence of low-density change on CT, the presence of vasospasm on angiography, clinical outcome as assessed by the Glasgow Outcome Score 3 months following the ictus, and the incidence of ischaemia as a cause of death or disability as assessed 3 months following the ictus. The levels of FPA found in blood and CSF from patients following SAH were significantly raised when compared with those found in controls. There was significant correlation between blood FPA levels and the amount of subarachnoid blood seen on initial CT. CSF FPA levels had a statistically significant correlation with outcome as assessed at 3 months post-ictus. No statistically significant correlation was found between blood or CSF FPA levels and any of the other variables studied.

Fibrinopeptide A↗
PubMed1991

A monoclonal antibody to a 67 kD cell membrane glycoprotein directly induces persistent platelet aggregation independently of granule secretion.

The transition from reversible to persistent platelet aggregation has been difficult to study because of interference both from preceding primary aggregation and from the events associated with granule secretion during secondary aggregation. As a result it remains unclear whether the persistence of aggregation involves some secretion-independent specific platelet surface reactions. Here we show that a monoclonal antibody (MAb), LeoAl, against a newly described 67 kD platelet membrane glycoprotein induced active platelet aggregation consisting of two distinct phases. The first secretion-independent phase was in several respects (extracellular protein, divalent cation, and pH dependence) different from primary aggregation, but closely resembled the transition from primary to secondary aggregation observed at certain concentrations of physiological agonists. The second, faster phase was indistinguishable from secretion-dependent aggregation to various stimulants. It was shown that p67, GPIIb-IIIa and FC gamma RII are all involved in the observed aggregation, probably through their close topographical association. It is suggested that LeoAl-induced aggregation can be used as a model to study the receptors, ligands and metabolic pathways specifically involved in the transition from reversible to persistent platelet aggregation.

Antibodies, Monoclonal↗
PubMed1991

Skin and gullet.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Rosacea and ulcerative colitis: a possible association.

Although rosacea was formerly believed to be associated with gastrointestinal upsets, no one any longer finds a significant association between rosacea and the intestinal tract. We describe four patients with a combination of ulcerative colitis and rosacea. In all four, ulcerative colitis preceded the onset of severe papulopustular rosacea, and we therefore feel that the severity of rosacea could have been due to the associated bowel disorder. In one, the severity and poor initial response of rosacea to treatment was clearly related to the activity of the ulcerative colitis, and the rosacea improved only after proctocolectomy. While it is possible that this purported association is fortuitous, we report these cases in the hope that others may have seen this combination of diseases, to our knowledge previously unreported.

Adult↗
PubMed1989

Characterization of a novel membrane glycoprotein involved in platelet activation.

When platelets bind certain specific ligands they are induced to secrete the contents of their cytoplasmic granules and to aggregate. Studies of the molecular events accompanying this vital physiological response have led to a greater understanding of cell activation in general since the pathways involved are common to a number of cell types. By contrast most of the information about the cell surface molecules that initiate signal transduction has emerged from work on T lymphocyte activation, a process essential to the initiation of the immune response. We have described an activation antigen on T lymphocytes that is involved in the differentiation of these cells. In the present report it is demonstrated that the antigen is expressed on the platelet membrane with about 1,200 copies/platelet. A monoclonal antibody detecting this antigen stimulates platelet secretion and aggregation with a half-maximal response at approximately 10(-8) M. Characterization of the antigen, termed PTA1, reveals a glycoprotein of Mr 67,000 showing extensive N-linked carbohydrate, much of which appears to be heavily sialated. The amino-terminal sequence of PTA1, EEVLWHTSVPFAEXMSLEXVYPSM, indicates that the protein has not previously been characterized. Preliminary investigation of the mechanism by which PTA1 mediates platelet activation suggests involvement of protein kinase C and the 47-kDa protein of platelets is rapidly phosphorylated upon antibody-mediated activation. During this process PTA1 is also phosphorylated, as it is following platelet activation by the other agonists, collagen, thrombin, and 12-O-tetradecanoylphorbol 13-acetate. These results provide the first example of a cell surface glycoprotein that is directly involved in both platelet and T lymphocyte activation.

Amino Acid Sequence↗
PubMed1989

Colchicine therapy in Behçet's syndrome--a report of five cases.

Five patients with Behçet's syndrome of varying duration were treated with colchicine (500 micrograms b.i.d.). All improved clinically and one has remained clear for 1 year after cessation of therapy, although in one patient who had neurological symptoms, paraesthesiae have persisted throughout treatment.

Adult↗
PubMed1989

Chronic granulomatous disease--a case showing long-term survival.

The diagnosis of chronic granulomatous disease of childhood was made in a 10-year-old boy following episodes of recurrent cervical abscesses and ulcerative stomatitis since the age of 4 years. Nineteen years on, on antibiotic prophylaxis, he is now married and remains active although he has been hospitalized with serious complications on many occasions.

Child↗
PubMed1989

Quantitative phase analysis in the assessment of coronary artery disease.

The phase image in radionuclide ventriculography shows the timing of ventricular contraction and is valuable in the detection of abnormalities induced by coronary artery disease. The image is usually interpreted subjectively, and in the present study a histogram of left ventricular phase values was used to make interpretation more objective. The left ventricular ejection fraction and the standard deviation, skewness, and kurtosis of the phase histogram were measured at rest, during isometric exercise, and during the final two stages of maximal dynamic exercise in 25 controls and 27 patients with coronary artery disease without previous infarction. The ejection fraction and the standard deviation of the phase had the same predictive accuracy for the presence of disease when measured during the penultimate stage of dynamic exercise (89%) as during the final stage, but their accuracy was lower during maximal exercise (77%) because of motion artefact at high exercise levels. Skewness and kurtosis of the histogram were of no value for the detection of disease, and isometric exercise was of only limited value. It is concluded that the phase histogram provides an objective measurement of the synchronicity of left ventricular contraction and can increase sensitivity for the detection of abnormality. Data should be acquired at all stages of dynamic exercise, and the penultimate stage should be used if there is any doubt about the validity of the final stage.

Adult↗
PubMed1989

Low-field cine magnetic resonance imaging in aortic valve disease.

Cine magnetic resonance imaging (MRI) holds considerable promise as a means of detecting abnormal blood flow patterns with the heart and great vessels. To date, the majority of techniques employed have required moderate to high field strengths. We describe a novel, low-field-strength approach that is technically undemanding and faster than conventional methods, which we have applied to the detection of aortic valve disease. A series of 26 patients with aortic stenosis or aortic regurgitation was compared with 21 normal subjects. All 20 patients with aortic stenosis and 15 of 16 patients with aortic regurgitation were identified. There were four false positives in the aortic stenosis group; all these patients had significant aortic regurgitation. There were no false positives in the aortic regurgitation group. Low-field cine MRI is a practical and useful technique for the detection of aortic valve disease.

Adolescent↗
PubMed1988

Gated cardiac tomography.

An ECG gated tomographic system is described and its application to routine diagnosis of cardiac wall dyskinesis discussed. The tomographic sections are gathered by a single section scanning system (Aberdeen Section Scanner). Technetium labelled red blood cells are used as the imaging agent. The time of the occurrence of the ECG R-wave is superimposed on the tomographic projection data stream and the gated images produced subsequently. The average patient study requires 15 min. Images at 8 phases of the cardiac cycle are generated at each of 5 levels, 16 mm apart, covering the length of the left ventricle. The images are stored as a three dimensional matrix and may be analysed in sections at any orientation. Fourier analysis of computer generated short axis sections are used to generate a set of coefficients describing the contraction of the left ventricle. The coefficients for each patient study are displayed as a series of two dimensional polar images, schematically displaying the spatial distribution of the coefficient over the left ventricle. These polar images are further analysed by comparison with distributions obtained from normal patient studies. The calculated deviations from the normal are then used to diagnose the magnitude and position of any dyskinesis. Initial results show that the tomographic system is capable of routinely detecting inferior cardiac wall dyskinesis, showing an advantage over non tomographic techniques.

Cardiomyopathies↗
PubMed1988

Genetic control of sebum excretion and acne--a twin study.

Sebum excretion and acne grades were measured in 20 pairs each of identical and non-identical like-sex twins. The identical twins had virtually identical rates of sebum excretion (P greater than 0.05), but they had a significantly different degree of acne severity (P less than 0.01). The non-identical twins had significantly different sebum excretion rates (P less than 0.01) and acne grades (P less than 0.01). These findings suggest that sebum excretion is under genetic control and the development of clinical lesions is modified by environmental factors.

Acne Vulgaris↗
PubMed1988

Differential sensitivity of radionuclide ventriculography for the detection of anterior and inferior infarction.

Attenuation of counts from the more distant inferior portion of the left ventricular blood pool in equilibrium radionuclide ventriculography may mean that inferior infarction is less likely to be detected than anterior infarction. Fourier amplitude and phase images can be used to map the extent and timing of regional ventricular wall motion and this study assesses their use for the detection of anterior and inferior infarction. Normal regional values of amplitude and phase were established in 38 individuals without evidence of cardiac abnormality. In 20 patients with anterior infarcts, though the sensitivity of the combined left anterior oblique amplitude and phase images was high (95%) it was lower (77%) in 39 with inferior infarcts, principally because the sensitivity of the phase image for the detection of inferior infarcts was only 39%. Right anterior oblique images generated from a first pass study detected all 13 patients with inferior infarcts. The mean left ventricular ejection fraction was significantly lower in the patients with anterior infarcts (37%) than in those with inferior infarcts (48%). Although the mean wall motion score on x ray contrast ventriculography was slightly lower in the patients with anterior infarction, the high sensitivity of the right anterior oblique amplitude and phase images in inferior infarction suggests that attenuation of counts is an important cause of reduced sensitivity of the left anterior oblique images. This may also partly explain the lower ejection fractions in inferior infarction. It follows that both a right anterior oblique first pass study and a left anterior oblique equilibrium study are necessary for an accurate description of regional wall motion.

Adult↗