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Biomedical subjects

P Butler

Publications and source records attributed to P Butler.

At least 91 records · Page 5Linked to original sources
PubMed1991

Digital subtraction angiography (DSA) of the extracranial cerebral vessels: a direct comparison between intravenous and intra-arterial DSA.

Fifty patients being investigated for ischaemic cerebrovascular disease underwent both intravenous digital subtraction angiography (IV-DSA) and intra-arterial arch digital subtraction angiography (arch-DSA) to enable a direct comparison to be made between the two techniques. The overall quality of the images obtained by arch-DSA was better than that obtained by IV-DSA, but there was no significant difference between the number and gradation of stenoses detected by the two techniques. No significant stenosis was missed by IV-DSA and the technique was found to be sufficiently accurate for it to be used as a screening procedure for carotid bifurcation stenoses suitable for carotid endarterectomy. The advantages and limitations of both techniques are discussed.

Adult↗
PubMed1991

The value of CT scanning in chronic suppurative otitis media.

High definition CT has been advocated for the evaluation of chronic suppurative otitis media (CSOM) either generally or in selected cases. It is said to be capable of producing the fine detail needed to detect lateral canal fistulae, exposed dura and facial canal dehiscences, and to demonstrate the ossicular chain. At present there is no agreement on either the indications for CT scanning in CSOM or the most appropriate scanning plane. To determine the value of high definition CT in CSOM and to decide a unit policy for its application, 36 cases of CSOM underwent pre-operative CT scanning and their scans were compared with the operative findings. Our results show CT to be highly sensitive to the presence of soft tissue disease and bone erosion, moderately sensitive to the presence of lateral canal fistulae but less sensitive to the presence of small areas of exposed dura, ossicular continuity and facial canal dehiscence. Axial scans were better able to demonstrate the lateral canal but otherwise coronal scans were superior; ideally patients should be scanned in both planes. The principle value of CT in CSOM is its ability to demonstrate disease which is not clinically apparent.

Cholesteatoma↗
PubMed1991

Mechanism of growth hormone-induced postprandial carbohydrate intolerance in humans.

Growth hormone excess can cause postprandial carbohydrate intolerance. To determine the contribution of splanchnic and extrasplanchnic tissues to this process, subjects were fed an isotopically labeled mixed meal after either a 12-h infusion of saline or growth hormone (4 micrograms.kg-1.h-1 [corrected]). Growth hormone infusion resulted in higher glucose and insulin concentrations both before and after meal ingestion. Despite growth hormone-induced hyperglycemia and hyperinsulinemia, postprandial hepatic glucose release and carbon dioxide incorporation into glucose (a qualitative estimate of gluconeogenesis) were similar to those present during saline, suggesting altered hepatic regulation. This was confirmed when glucose was infused in the absence of growth hormone to achieve glucose (and insulin) concentrations comparable to those present during growth hormone infusion. Although growth hormone excess did not alter splanchnic uptake of ingested glucose, it resulted in a fivefold increase in postprandial hepatic glucose release (578 +/- 31 vs. 117 +/- 10 mg.kg-16 h-1, P less than 0.01), less suppression of carbon dioxide incorporation into glucose (-13 +/- 9 vs. -53 +/- 12 mg.kg-1. 6-h-1, P less than 0.01), and lower glucose uptake (1,130 +/- 59 vs. 1,850 +/- 150 mg.kg-1.6 h-1, P less than 0.01). The decrease in postprandial glucose uptake did not appear to be mediated by a change in substrate uptake since postprandial plasma concentrations and forearm balance of lactate, free fatty acids, and ketone bodies did not differ in the presence and absence of growth hormone excess.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1990

Small deep cerebral infarcts associated with occlusive internal carotid artery disease. A hemodynamic phenomenon?

Small deep cerebral infarcts, often referred to as lacunes, have been traditionally associated with small-vessel disease affecting the deep penetrating arterial system. We describe 10 cases where these infarcts were associated with severe, ipsilateral internal carotid artery occlusive disease. Seven of these patients also had severe occlusive disease of the contralateral internal carotid artery. The clinical and radiologic features, in combination with studies of cerebral blood flow, were consistent with hemodynamically mediated cerebral ischemia. Occlusive internal carotid artery disease may be more commonly associated with hemodynamic cerebral ischemia than previously believed, and small cerebral infarcts in the deep arterial border zone areas are likely to be an important manifestation of this process.

Adult↗
PubMed1990

Feasibility of percutaneous transluminal angioplasty for carotid artery stenosis.

Percutaneous transluminal balloon angioplasty was attempted in seven patients with internal carotid artery stenosis, including one patient who had two procedures. All had recurrent, carotid territory, neurological symptoms considered haemodynamic in origin. Six had occlusion of the contralateral internal carotid artery. Cerebral blood flow studies confirmed diminished cerebrovascular reserve in six patients studied. In five patients (six procedures) angioplasty of the stenosed internal carotid artery was carried out successfully. With two patients technical difficulty in crossing the stenosis prevented angioplasty and in one patient with bilateral stenosis the procedure was not attempted on the second side because of the severity of the stenosis. In two patients transient aphasia developed during cannulation of the carotid artery and in another a transient monoparesis developed during the procedure. Both these haemodynamic complications recovered within ten minutes. No other complications occurred. Our experience suggests that balloon angioplasty is technically feasible in the management of stenotic carotid disease associated with haemodynamic stroke. It is a technically simple procedure requiring only a brief admission to hospital. However, its general application to patients with thromboembolic carotid-territory stroke will depend on the risk/benefit ratio compared to carotid endarterectomy or to conventional medical treatment.

Angiography, Digital Subtraction↗
PubMed1990

Cerebellar syndrome with hydrocephalus due to Mycoplasma pneumoniae infection.

A 27 year old woman developed a cerebellar syndrome with serological evidence of recent Mycoplasma pneumoniae infection. The cranial computed tomographic scan showed effacement of the fourth ventricle, enhancement of the basal meninges and hydrocephalus affecting the lateral and third ventricles. Clinical and radiological recovery occurred over 5 weeks. We propose that this was a manifestation of immune-mediated encephalomyelitis induced by the infection rather than direct invasion of the central nervous system.

Adult↗
PubMed1990

Insulin resistance in type II diabetes mellitus.

In vivo studies indicate that patients with NIDDM have defects in both insulin secretion and insulin action. The decrease in insulin action is due to both hepatic and extrahepatic insulin resistance. The impairment in glucose uptake is associated with alterations in both oxidative and nonoxidative disposal. Defective glucose transport may limit both of these processes. NIDDM also is associated with increased concentrations and rates of oxidation of plasma free fatty acids. Insulin resistance appears to be familial and in at least some individuals antedates glucose intolerance. In vitro studies indicate that insulin resistance can involve a variety of insulin sensitive tissues including adipocytes, muscle and liver. While most studies note that insulin binding and insulin receptor kinase activity are decreased in insulin sensitive tissues in obese patients with NIDDM, further delineation of the contribution of obesity and diabetes is required. Alterations in glucose transporter number and function likely account at least in part for impaired glucose transport. The cause of the alterations in other insulin responsive pathways and the role of an abnormal metabolic milieu versus intrinsic cellular defects remain to be established.

Adipose Tissue↗
PubMed1990

Choice and use of tracers.

The isotope dilution method has been widely employed to measure glucose turnover in man. The validity of this technique depends upon several assumptions. First, it is assumed that the selected model of glucose kinetics is valid. Under nonsteady state conditions this has recently been challenged for the most commonly used single compartment model. Secondly, it is assumed that the isotope is metabolized in the same manner as unlabeled glucose. If the isotope loses its label when subject to a substrate cycle (for example, [2-3H]glucose in glucose to glucose 6-phosphate cycling), an overestimate of glucose disposal will result. In contrast, if isotope that has been cleared (for example [6-3H]glucose in hepatic glucogen) is recycled into the systemic circulation, an underestimation of glucose turnover will result. Thirdly, it is assumed that measurement of specific activity is accurate. It has recently been shown that many commercially available tritiated (but not 14C) isotopes contain radioactive nonglucose contaminants which have a slower clearance rate than glucose under conditions of high glucose turnover. This can result in overestimates of specific activity and underestimates of glucose appearance, leading to calculated negative hepatic glucose release. While this problem may be avoided with purified tritiated glucose tracers, a similar problem with stable isotopes of glucose remains to be determined. In summary, the choice of glucose isotope should reflect the probability of substrate cycling and isotope cycling in the experiment in question. Care should be taken to ensure purified isotopes are selected and that the model of glucose kinetics used is valid during the conditions to be studied.

Animals↗
PubMed1989

Antimitochondrial antibodies in primary biliary cirrhosis recognize both specific peptides and shared epitopes of the M2 family of antigens.

Sera from patients with primary biliary cirrhosis exhibit variable autoantibody reactivity against mitochondria, the commonest antigen (designated M2) including three structures of approximate M.W. 70, 50 and 40 kD. The nature of these antigens has only recently been established; the 70 and 50 kD are the transacetylase E2 and component X, respectively, of the pyruvate dehydrogenase complex and are distinct polypeptides. We have demonstrated, by immunoblotting, elution and rebinding of antibodies, unequivocal cross-reactivity between the major bands of the M2 antigen. In addition, cross-reactivity has been shown between antibodies binding to each of the three M2 bands of mitochondria and two major antigenic bands of both Gram-negative and Gram-positive bacteria. Conversely, antibodies eluted from these two bands of Escherichia coli were found to bind all three M2 bands of mitochondria. These results suggest that the antibodies of primary biliary cirrhosis contain both peptide-specific and cross-reacting antibodies, the latter recognizing a common "M2 epitope" that might include nonprotein components of the peptides. However, direct and competitive enzyme-linked immunosorbent assays failed to implicate the coenzyme of the pyruvate dehydrogenase complex, lipoic acid or its amide, as the common antigenic moiety.

Autoantibodies↗
PubMed1989

Digital subtraction angiography (DSA). Work load and financial implications for a neuroradiology department.

A four year study has been undertaken into the effects on the workload and cost implications of the introduction of digital subtraction angiography (DSA) in a large United Kingdom teaching hospital. The increase in workload has been entirely due to the ability to perform intravenous angiography. DSA is cheaper than conventional angiography if more than 210 cases are undertaken each year. This difference is accounted for by the reduced use of X-ray film. However, intravenous angiography is more expensive because of the use of large volumes of nonionic medium.

Angiography↗
PubMed1988

Digital subtraction angiography of the left ventricle.

Twenty-eight patients have been studied by left ventricular angiography and digital subtraction angiography, using either a peripheral venous injection (16) or a central venous injection (12) of contrast medium. Digital subtraction angiography compared favourably to angiography in the qualitative assessment of left ventricular size and function. Measurement of ejection fraction demonstrated a good correlation (r = 0.83) between digital subtraction angiography and left ventricular angiography. In the assessment of left ventricular segmental wall motion the use of a central venous injection, particularly in those patients with severely impaired ventricular function, proved superior to the use of a peripheral injection.

Coronary Disease↗
PubMed1988

Scoliosis examinations: organ dose and image quality with rare-earth screen-film systems.

We determined the dose to the breast and evaluated the image quality when various high-speed, rare-earth screen-film systems were used in conjunction with breast dose reduction methods in children undergoing scoliosis examinations. In addition, normalized organ dose to the breast, active bone marrow, thyroid, eyes, ovaries, and testes were measured in a pediatric anthropomorphic phantom comparing the anteroposterior and posteroanterior projections. The average measured dose to the breast was 6.9 and 4.0 mrad (10(-5) Gy), respectively, for nominal 400- and 600-speed, rare-earth screen-film systems used in combination with breast dose reduction methods. The image quality of these systems as evaluated by three radiologists was rated as adequate. The dosimetry results with an anthropomorphic phantom showed that the posteroanterior projection provides approximately a threefold reduction in breast dose as compared with the anteroposterior view. However, the dose to the bone marrow is doubled. Rare-earth screen-film systems used in combination with simple dose-reduction methods can provide adequate image quality for scoliosis examination while significantly reducing the radiation dose to the breast.

Adolescent↗
PubMed1987

Arterial PaO2 and PaCO2 influence seizure duration in dogs receiving electroconvulsive therapy.

The influence of arterial O2 and CO2 tensions on electroconvulsive seizure duration was investigated in five mongrel dogs under consistent anaesthetic conditions. Seizure durations were measured in a randomized protocol of nine possible combinations of arterial gas tension spanning increased, normal or decreased levels of PaO2 and PaCO2. Seizure duration was directly related to PaO2 (p less than 0.00001) and inversely related to PaCO2 (p less than 0.0001). A significant synergism was evident at the extremes of PaO2 and PaCO2, with seizure duration being greater than predicted for hyperoxia-hypocapnia and hypoxia-hypercapnia and shorter than predicted for hypoxia-hypocapnia and hyperoxia-hypercapnia. We conclude that arterial gas tensions strongly influence ECT-induced seizure duration and through this may influence the therapeutic efficacy of electroconvulsive therapy.

Animals↗