Biomedical subjects

M Girton

Publications and source records attributed to M Girton.

32 records · Page 2Linked to original sources

PubMed1979

Bile duct cysts secondary to liver infarcts: report of a case and experimental production by small vessel hepatic artery occlusion.

Hepatic bile duct cysts were demonstrated on an abdominal CT scan and confirmed at autopsy in a patient with polyarteritis nodosa. The cysts developed in close proximity to hepatic artery aneurysms and occlusions visualized at hepatic arteriography and confirmed postmortem. The development of similar bile duct cysts following hepatic artery occlusion was demonstrated in 13 Rhesus monkeys.

Aneurysm↗

PubMed1979

Acute occlusion of the posterior spinal vein. Experimental study in monkeys.

The posterior spinal vein was occluded with silicone in seven rhesus monkeys, and locally resected in one. There were no neurological findings associated with acute venous obstruction of the cord. Follow-up arteriography revealed diversion of venous outflow into the anterior spinal venous system. Histology revealed gliosis associated with demyelinization confined to the posterior columns.

Angiography↗

PubMed1978

A rapidly polymerizing polyurethane for transcatheter embolization.

A polyurethane prepolymer was evaluated as a transcatheter embolizing agent. Low viscosity permits injection through small catheters. Polymerization is initated on contact with blood and completed within 10 seconds. Downstream propagation is better then that of cyanoacrylate and comparable to that of silicone rubber. No systemic toxicity was observed in acute animal experiments. However, dissolution of arterial walls and extravasation out of the vascular bed of chronically embolized organs suggest significant local tissue toxicity and make further evaluation necessary before clinical testing.

Abscess↗

PubMed1978

Proximal versus peripheral hepatic artery embolization experimental study in monkeys.

A case is described in which extensive embolization of the hepatic artery to reduce insulin production by a metastatic islet-cell tumor resulted in liver failure, intrahepatic abscesses, and death. The difference between proximal and peripheral hepatic artery obstruction was investigated in monkeys by embolizing hepatic arterial beds with Gelfoam and silicone. Gelfoam obstructed proximally, arterial collaterals developed rapidly, and liver function remained normal. Peripheral hepatic artery embolization with silicone produced liver infarction and severe functional abnormalities. Peripheral hepatic artery occlusion was more effective in preventing the development of collateral circulation but involved a significant risk of hepatic failure or abscess.

Adenoma, Islet Cell↗

PubMed1978

Role of vascular proliferation on angiographic appearance and encapsulation of experimental traumatic and metastatic brain abscesses.

Experimental traumatic abscesses were produced in rhesus monkeys by intracerebral injection of nutrient agar contaminated with Staphylococcus epidermidis, and metastatic abscesses were induced by intracarotid embolization of silicone cylinders contaminated with Staphylococcus epidermidis. All monkeys underwent preoperative and serial postoperative carotid angiography. Traumatic abscesses produced early capsular blushes and progressive anterior cerebral artery displacements. Metastatic abscesses induced transient midline shifts but no capsular stains. Postmortem studies on the monkeys showed that mean capsular thickness and segmental wall vascularity of the traumatic and metastatic abscesses were significantly different (p less than 0.001), despite equal abscess ages and similar abscess volumes. In comparison to traumatic abscesses, metastatic abscesses demonstrated reduced inflammatory cell infiltration and retarded collagen formation around proliferating capsular vessels. Brain surrounding the metastatic abscesses demonstrated ischemic changes. The results suggest that 1) capsular blushes during cerebral angiography are secondary to vascular proliferation within the capsule and not to compression of surrounding brain, 2) vascular staining reflects capsular thickness, 3) capsular vascularity contributes to collagen formation, 4) encapsulation is dependent upon the integrity of surrounding brain, and 5) adjacent cerebral ischemia may impede inflammatory responses involved in capsule formation.

Animals↗

PubMed1978

Ventilation-perfusion lung imaging and selective pulmonary angiography in dogs with experimental pulmonary embolism.

To determine the accuracy and limitations of Xe-133 ventilation and Tc-99m perfusion lung images (V-P images) in detecting pulmonary emboli (PE), these studies were performed in 23 dogs after experimental production of PE by a modified Wessler technique. Fourteen of the animals also underwent selective pulmonary angiography. Xenon-133 abnormalities were seen immediately after embolization in two of the 23 animals (8.7%). Perfusion images revealed the location of 83% of emboli that completely obstructed pulmonary vessels, but only 26% of those that partially obstructed flow. Defects were seen with 97% of emboli that completely occluded vessels larger than 2.0 mm in diameter, but in only 66% of those occluding smaller vessels. Oblique perfusion images provided the only evidence of the perfusion defect associated with five of 88 (5.7%) angiographically proven emboli. V-P imaging is a sensitive technique for detecting PE unless the emboli lodge in very small vessels or incompletely obstruct a vessel. Xenon-133 abnormalities occur infrequently following PE, and should not be a common cause for a false-negative V-P match in clinical practice.

Angiography↗

PubMed1977

Computed tomographic demonstration of hepatic tumor with the aid of intravenous iodinated fat emulsion. An experimental study.

Computed tomography showed improved visualization of carcinogen-induced hepatoma in monkeys following intravenous injection of an experimental contrast material AG 60-99; selective opacification of the liver and spleen was accomplished with a dose of greater than or equal to 0.1 ml/kg, a fraction of the dose used in conventional x-ray tomography. This marked reduction was made possible by the improved density resolution of the CT scanner. This may be the first organ-specific contrast material intended primarily for use with CT scanners.

Animals↗

PubMed1977

Absence of vasospastic response of the anterior spinal artery to subarachnoid blood.

Autologous blood (0.3 to 5.0 ml) was introduced into the lumbar subarachnoid space of nine monkeys. Serial spinal cord arteriography was performed at frequent intervals over a 24-hour period. Magnification techniques permitted direct measurement of the anterior spinal artery and posterior spinal vein. Neither immediate nor delayed spasm was observed in any animal. Similar techniques have routinely produced spasm of intracranial arteries in our laboratory.

Animals↗

PubMed1976

Angiographic study of the effect of laminectomy in the presence of acute anterior epidural masses.

Laminectomies were performed in 16 monkeys to decompress simulated acute epidural masses in front of the spinal cord. When decompression restored normal arterial and venous hemodynamics, the monkeys were neurologically intact in spite of considerable mechanical distortion of the cord. When either the anterior spinal artery or the posterior spinal vein remained obstructed following laminectomy, the monkeys were paraplegic. Acute anterior epidural masses larger than 4 mm in diameter could not be adequately decompressed via the posterior approach. Only minor posterior displacement of the cord is observed following laminectomy in the presence of large anterior masses.

Angiography↗

PubMedDate not supplied

Experimental comparison of EOE-13 and perfluoroctylbromide for the CT detection of hepatic metastases.

The relative advantages of EOE-13 and perfluoroctylbromide (PFOB) as contrast agents were evaluated using CT scanning in animals with implanted liver tumors. Three criteria were used to compare these compounds: (1)the density difference between liver and tumor, (2)the presence of opacification of intrahepatic vascular structures, and (3)the presence of ring enhancement around the tumors. All three radiographic features were superior in the scans after injection of 5 g/kg of PFOB. When a reduced dose (1.7 g/kg) of PFOB was used, however, the scans obtained with EOE-13 were of approximately equal quality. It is concluded that if toxicity problems prevent administration of PFOB in humans, then EOE-13 will probably remain the contrast agent of choice for tumor imaging in the liver.

Animals↗

PubMedDate not supplied

CT evaluation of hepatic and splenic trauma with EOE-13. An experimental study in monkeys.

EOE-13 is a liver-spleen specific CT contrast agent currently undergoing clinical trials. It is an aqueous emulsion of iodinated fatty acids. We studied eight rhesus monkeys with surgically created blunt trauma to the liver and spleen. The animals were examined using CT scans without contrast material and CT scans with EOE-13. Scans were performed at times between 3 hours and 24 hours after trauma. The presence of parenchymal injury was shown better EOE-13 (P less than 0.01). The use of EOE-13 permitted earlier diagnosis in both the liver and spleen. This contrast agent has potential for the evaluation of trauma in clinical practice, and may be particularly useful in children.

Animals↗

PubMedDate not supplied

Opening of blood-ocular barrier demonstrated by contrast-enhanced MR imaging.

Opening of the blood-ocular barrier following infusion of hyperosmolar agents into the internal carotid artery has been demonstrated by gadolinium enhanced magnetic resonance (MR) imaging. In five rhesus monkeys the disruption of the barrier was shown as increased signal intensity within the aqueous and vitreous humors. These findings suggest a potential use of contrast-enhanced MR imaging for detecting and evaluating the ocular microangiopathy of diabetic and hypertensive retinopathy and other diseases.

Animals↗

PubMedDate not supplied

Direct infusion of EOE-13 into the hepatic artery. Experimental evaluation of safety in monkeys.

Ethiodized Oil Emulsion 13 (EOE-13) is an intravenous liver-spleen specific CT contrast agent. We infused EOE-13 directly into the hepatic arteries of five rhesus monkeys. Normal saline was administered in the same fashion in two control animals. Serial laboratory studies showed no major toxicity over a seven-day period. Intra-arterial EOE-13 has potential usefulness in the evaluation of hepatic artery infusion chemotherapy.

Animals↗

PubMedDate not supplied

Ethyl alcohol: experimental agent for interventional therapy of neurovascular lesions.

Perfusion of absolute ethyl alcohol into the middle cerebral artery of six rhesus monkeys was performed using the Pevsner miniballoon catheter system. The animals were sacrificed by thoracotomy and intracardiac perfusion of a mixed aldehyde solution for fixation. Preliminary angiography and electron microscopy suggest absolute ethyl alcohol is a good neurovascular occlusive agent, and a possible replacement for isobutyl 2-cyanoacrylate in the treatment of angiomas and tumors.

Animals↗