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Biomedical subjects

D J Allison

Publications and source records attributed to D J Allison.

At least 145 records · Page 8Linked to original sources
PubMed1971

Adrenal catecholamine secretion during stimulation of the nasal mucous membrane in the rabbit.

1. Left adrenal venous blood was collected in anaesthetized rabbits and analysed for catecholamine content by either a fluorimetric technique or a bio-assay method using the blood pressure of the pithed rat.2. Stimulation of the nasal mucous membrane with ether vapour or water caused apnoea, bradycardia, a rise in arterial blood pressure and an increase in adrenal medullary catecholamine secretion.3. During the pre-stimulation control periods adrenaline constituted 66% of the total catecholamine present in adrenal venous blood and noradrenaline 34%. These proportions altered during stimulation of the nasal mucous membrane to 72 and 28% respectively. Electrical stimulation of the left splanchnic nerve produced a secretion composed almost entirely of adrenaline.4. The increased catecholamine output elicited during stimulation of the nose occurred in animals whose pulmonary ventilation was maintained constant by means of a pump. It was abolished, however, by local anaesthesia of the nasal passages or by surgical division of the left splanchnic nerve.5. The increased secretion of catecholamines is therefore reflex in nature, and evidence is presented that it is the result of a primary reflex from the nose.

Adrenal Medulla↗
PubMedDate not supplied

Treatment of high-flow vascular malformations by venous embolization aided by flow occlusion techniques.

PURPOSE: Transvenous embolization techniques may be helpful as alternatives to the arterial route when treating high-flow vascular malformations. We present our experience using these techniques in four patients. METHODS: In one patient the venous portion of the arteriovenous malformation (AVM) was punctured directly; in the other three patients it was catheterized via a retrograde venous approach. Flow occlusion techniques were utilized in all patients during embolization, which was performed with absolute alcohol or N-butyl-2-cyanoacrylate. RESULTS: Excellent clinical and angiographic results were obtained, with obliteration of arteriovenous shunting in all patients. There were no complications. CONCLUSION: The embolization of certain AVMs using a venous approach is a safe and effective treatment.

Adolescent↗
PubMedDate not supplied

Arterial embolization in the management of liver metastases.

Hepatic arterial embolization has been shown to be a safe and effective method for the palliation of symptoms in patients with metastatic disease, particularly those with secondary deposits from endocrine tumors. This review examines the indications for the procedure, discusses some aspects of technique, and assesses the potential benefits and complications of the method.

Embolization, Therapeutic↗
PubMedDate not supplied

Endovascular stents and stent-grafts: is heparin coating desirable?

Heparins are glycosaminoglycans that, in addition to their anticoagulant activity, have interactions with growth factors and other glycoproteins. These interactions may stimulate neointimal hyperplasia when heparin is delivered locally on stents and stent-grafts. Modifying the structure of heparin to retain anticoagulant activity while minimizing these stimulatory effects on the vascular endothelium is desirable and may be achieved by understanding the relationships between the structure and function of the various parts of the heparin molecule.

Animals↗
PubMedDate not supplied

Treatment of carcinoid liver metastases by hepatic-artery embolisation.

Two patients with multiple hepatic carcinoid metastases experienced considerable symptomatic relief after the hepatic artery was embolised with fragments of absorbable gelatin sponge administered through a percutaneous arterial catheter. With adequate pharmacological cover the technique is a safe, effective, and relatively painless treatment for a condition which is usually very difficult to manage.

Adult↗
PubMedDate not supplied

Penetration of the holmium:YAG laser through fluid.

PURPOSE: The 2.1-microns pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser combines the properties of transmissibility down a flexible silica fiber, enabling percutaneous or endoscopic use, with high water absorption, suggesting good safety characteristics. Laser attenuation in practice, however, is an extremely complex process. The authors studied its effective penetration through blood, bile, urine, saline, and contrast media. MATERIALS AND METHODS: With use of a fiberoptically directed beam and a laser power meter, penetration was measured in vitro with the fiber tip separated from the medium by 5 cm (noncontact mode) and with the fiber tip immersed (contact mode). Logarithm of energy falloff was measured against fluid thickness. Attenuation coefficients (mu) and half value layer (HVL) distances (estimated thickness of fluid needed to have power) were measured. RESULTS: In noncontact mode, power falloff was exponential. Non-sanguinous media had similar values for mu and HVL (mu = 2.24-2.70 mm-1 and HVL = 0.26-0.31 mm) close to theoretical predictions. Blood caused significantly (P < .05) more attenuation (mu = 5.15 mm-1, HVL = 0.13 mm). In contact mode, attenuation was much more complex with "plateau" distances of up to 1.2 mm, below which attenuation was negligible. The HVL distances ranged from 0.9 to 1.8 mm and were up to 14 times higher. The main reason is probably the formation of microcavities around the fiber tip. CONCLUSION: The effective penetration of this laser when immersed may be several times that predicted, with important clinical implications.

Absorption↗
PubMedDate not supplied

1979 George Simon Memorial Fellowsip Award. A radiologic and physiologic investigation into hypoxic pulmonary vasoconstriction in the dog.

We examined the site and mechanism of hypoxic vasoconstriction in a single lobe of the dog lung. In anesthetized dogs pulmonary arteriography in an exteriorized lung lobe showed vasoconstriction during hypoxia. The vasoconstriction was maximal in the smallest vessels studied (300-micrometer diameter), in which a 19% reduction in diameter was observed during hypoxia; no significant change in caliber occurred in vessels exceeding 2 mm in diameter. Reversal of the vascular response occurred upon withdrawal of the hypoxic stimulus. In a second study using the same model, saralasin acetate, a specific competitive antagonist of angiotensin II, failed to modify the constrictor response to hypoxia. It is concluded from these studies that the site of the increased pulmonary vascular resistance evoked by alveolar hypoxia is located predominantly in the small pulmonary arteries, and that angiotensin II plays no significant role in the mediation of the response.

Angiography↗
PubMedDate not supplied

Ileocolic intussusception in large cell lymphoma of the terminal ileum. Report of a case.

A case of an adult patient with ileocolic intussusception secondary to a lymphoma of the terminal ileum is reported. On the computed tomograms, a target mass, with the outer rim representing the annular tumour of the terminal ileum and the eccentric rim of low attenuation representing the mesentery, is described. Ultrasound patterns are those of parallel hypoechoic areas separated by hyperechoic stripes seen on longitudinal sections, and of a rounded mass of low echogenicity, exhibiting two hyperechoic concentric ring-like areas within it, on transverse scans. The appearances of the barium examinations are also described. The English literature is reviewed.

Humans↗
PubMedDate not supplied

Hot spot: planning, design and construction is the right remedy for ED dangers.

The article presents some special planning and design tactics that can improve your hospital's security for the site areas adjacent to or serving the emergency department. EDs designed and built to embody the principles provided, say the authors, will achieve a good balance between the level of openness needed to treat patients and the level of security needed to protect patients, visitors, and staff.

Emergency Service, Hospital↗