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Biomedical subjects

S Wallace

Publications and source records attributed to S Wallace.

At least 235 records · Page 13Linked to original sources
PubMed1988

Self-expanding endovascular graft: an experimental study in dogs.

An arterial endovascular graft was constructed by wrapping an expandable nylon mesh around a framework of Gianturco self-expanding metallic stents. The devices were passed through a 12-French Teflon catheter and positioned in the normal abdominal aorta of five dogs, two of which also had a device placed in an external iliac artery. At follow-up (1-6 months), all grafts remained patent, even though slight luminal narrowing due to neointimal encasement was noted. Histologically, all grafts were covered by neointimal proliferation at the time of removal. The graft material expanded with the stents, resulting in a tight fit between the graft and the vessel wall. Side branches narrowed but remained open because of the size of the nylon mesh. No migration of the grafts equipped with a barbed lead stent was noted. Expandable nylon mesh can be used as an endovascular graft material when wrapped around a framework of self-expanding stents. The resulting device can be easily delivered via transcatheter techniques, and once placed in a vessel, the nylon acts as a support for neointimal encasement, which forms a new vascular lumen.

Animals↗
PubMed1988

Arterial embolization of adrenal tumors: results in nine cases.

Adrenal arterial embolization was performed in nine patients, four with inoperable adrenal cortical carcinoma and five with metastatic adrenal tumors. Embolic agents used were polyvinyl alcohol foam (Ivalon) in seven patients, stainless steel coils in four, ethanol in three, and surgical gelatin (Gelfoam) in two. In eight patients, embolization was performed for palliation, either to decrease tumor bulk (all patients), suppress tumor hormonal function (three patients), or relieve pain (four patients). One patient had an embolization to facilitate subsequent adrenalectomy. In four patients in whom it was possible to assess the effect of embolization on tumor bulk by follow-up CT, a striking reduction in size has occurred in one, the lesions remained stable in size for 12 months in two, and the tumor continued to increase in size in the fourth. A striking reduction in the production of the cortisol for 12 months was seen in two of three patients with Cushing syndrome. This reduction was considered due at least in part to embolization. Adrenal embolization resulted in effective palliation of pain in three of four patients and may have contributed to palliation in the fourth. Apart from a hypertensive episode in one patient, the cause of which was unclear, no serious side effects occurred. Adrenal arterial embolization may play an effective role without serious side effects in palliation of pain and reduction of hormone production in inoperable adrenal lesions.

Adrenal Gland Neoplasms↗
PubMed1988

Islet cell tumors metastatic to the liver: effective palliation by sequential hepatic artery embolization.

The value of sequential percutaneous hepatic artery embolization with polyvinyl alcohol particles was examined in 22 patients with islet cell carcinoma metastatic to the liver. Nine patients had gastrinoma, 2 had glucagonoma, and 11 had no discernible hormonal secretions or syndromes. Ninety-seven embolizations were done with a median number of 4 (range, 1 to 12) per patient. The interval between embolizations ranged from 1 to 8 months. Twelve of twenty evaluable patients had a partial remission, frequently associated with subjective improvement and decrease in hormone levels. The projected median survival of all 22 patients from the initiation of embolization is 33.7 months (range, 1 to 72). Nausea, vomiting, fever, and abdominal pain occurred with each embolization and subsided usually by day 10 (range, 3 to 35). Sequential hepatic artery occlusion is an effective method for prolonged palliation in this selected group of patients.

Adenoma, Islet Cell↗
PubMed1988

Surgery of metastatic renal cell carcinoma and use of renal infarction.

Surgery can play an important role in selected patients with metastatic renal cell carcinoma although nephrectomy alone neither promotes regression of metastases nor improves survival. However, nephrectomy preceded by renal infarction and followed by medroxyprogesterone acetate produced ten complete responses, nine partial responses, and 22 stabilizations among 145 patients (CR + PR = 13%; overall response rate = 28%). Only patients with parenchymal pulmonary metastases without adenopathy, pleural effusion, or other organ involvement responded consistently (23% objective, 41% overall), and we currently recommend this combination therapy only for this group. However, infarction alone is an easy way to palliate symptoms due to primary or secondary tumors.

Carcinoma, Renal Cell↗
PubMed1987

Intrahepatic infusional therapy for metastatic ovarian carcinoma.

Twenty-four women with ovarian carcinoma that had metastasized to the liver were treated with intrahepatic infusional therapy. No consistent drug regimen was used. There were no complete responders; however, 33% had a partial response. All responses were noticed after the first course of therapy. The median length of response was 6.3 months. The median survival from the time of the first hepatic infusion was 7.5 months for all patients. In this series, there were two treatment-related deaths, one secondary to the chemotherapy, the other to improper catheter placement. Because of the multiplicity of chemotherapy regimens employed, no definite conclusions can be made concerning the efficacy of intrahepatic infusional therapy for metastatic ovarian carcinoma. It is suggested that its future use be restricted to patients with disease limited to the liver and who are being treated according to a study protocol.

Adolescent↗
PubMed1987

Pathologic fracture in osteosarcoma. Impact of chemotherapy on primary tumor and survival.

Twenty patients with osteosarcoma and pathologic fractures were treated with a chemotherapeutic regimen consisting of cis-diamminedichloroplatinum-II (CDP), Adriamycin (ADR) (doxorubicin) and high-dose methotrexate with citrovorum factor "rescue" (MTX-CF). Before the introduction of the regimen, the primary tumor in two patients was treated by immediate amputation and in 13 with preoperative intra-arterial CDP. Among these 13 patients, responses (healing) were observed in 11 (one required the addition of radiation therapy). In three patients, the responses were so dramatic that, at their request, surgery was deferred and treatment exclusively with chemotherapy was instituted. Based on this experience, treatment exclusively with chemotherapy was also administered to an additional five patients who were admitted without pathologic fractures. In the course of such treatment, pathologic fractures also developed; notwithstanding, chemotherapy was maintained and healing also occurred. One of the 20 patients had pulmonary metastases at diagnosis; these were resected after treatment and pathologic examination revealed no evidence of viable tumor. The remaining 19 patients were free of pulmonary metastases but these later developed in seven patients. These data were compared to a historical control series in which 16 of 21 patients with pathologic fractures developed pulmonary metastases. Three of the chemotherapy treated patients died of nonosteosarcoma related causes (leukemia, generalized varicella, and a metabolic complication). Overall, survival was improved in the chemotherapy treated patients as compared to the historical control series: 10 of 20 versus 6 of 21, respectively. Pathologic fractures in osteosarcoma may heal under treatment with chemotherapy, which also has a favorable impact on the eradication of pulmonary metastases and survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Intracarotid VP-16 in malignant brain tumors.

Twenty-eight patients with malignant brain tumors (16 with primary brain tumors and 12 with brain metastases) progressing after cranial irradiation with or without chemotherapy received varying doses of intracarotid VP-16. Courses of therapy were repeated every 4 weeks along with computerized axial tomography scan and neurologic examination. Of 15 evaluable patients with primary malignant brain tumors, 1 responded to therapy and 5 had no immediate tumor progression for 2-10 months. None of 12 evaluable patients with brain metastases responded to intracarotid VP-16 although 5 had no immediate tumor progression from 1-4 months. Side effects of treatment were uncommon. Using this route of administration, intracarotid VP-16 does not appear to increase response rates in patients with primary malignant brain tumors, compared with results reported for intravenous VP-16.

Adolescent↗
PubMed1987

Repositioning misplaced central venous catheters.

Central venous catheters inserted through the subclavian or basilic veins may be misplaced in the internal jugular vein. A simple technique employing a deflector guide wire allows catheter reposition in a very short time without the need for catheter withdrawal. In this manner, radiation exposure, the risk of catheter contamination, and patient discomfort are lessened.

Catheterization, Central Venous↗
PubMed1987

Gastroduodenal mucosal injury during hepatic arterial infusion of chemotherapeutic agents. Lack of cytoprotection by prostaglandin E1 analogue.

Eighteen colorectal cancer patients with liver metastases receiving hepatic arterial infusion of chemotherapeutic agents (mitomycin-C + 5-FUDR) were randomized to receive misoprostol (a prostaglandin E1 analogue) or placebo as a mode of cytoprotection against inadvertent gastroduodenal mucosal injury. Four of 10 patients on misoprostol and 3 of 8 patients on placebo developed gastroduodenal mucosal injury (p greater than 0.1), which was confirmed by endoscopy. Significant tumor responses to chemotherapy were equally distributed between the two groups. Although our sample size was small and type II error (false-negative trial) cannot be excluded, these data strongly suggest that prophylaxis with misoprostol does not prevent the acute gastroduodenal mucosal injury associated with hepatic arterial infusion of chemotherapeutic agents.

Alprostadil↗
PubMed1987

Experimental comparison between hepatic artery infusion and occlusion-infusion of adriamycin.

Adult mongrel dogs were used to compare hepatic arterial infusion and arterial occlusion-infusion with regard to local and systemic Adriamycin levels. The drug was infused into the right proper hepatic artery of each dog after occlusion of the gastroduodenal artery. Blood and tissue samples were collected at regular intervals for Adriamycin determination. Four weeks later, each dog again received the same agent in the right proper hepatic artery, but this time arterial flow was blocked with an inflated balloon during drug infusion (arterial occlusion-infusion). Blood and tissue drug levels were determined and compared with those obtained using infusion without occlusion. Results indicate that when Adriamycin is administered into the hepatic artery of dogs, occlusion-infusion produces significantly greater hepatic venous drug levels, drug uptake, and drug metabolism than does infusion alone.

Animals↗
PubMed1987

Flexible balloon-expanded stent for small vessels. Work in progress.

A new type of flexible, balloon-expanded, stainless steel stent was designed for introduction into small vessels subject to motion. Four stents placed in four dogs were patent at follow-up (4-8 weeks). A fibrocellular proliferation involving the intima and media was responsible for a 20%-25% luminal narrowing observed in all vessels with stents. The stent has longitudinal flexibility, which should permit its insertion into small peripheral, visceral, and coronary arteries.

Animals↗
PubMed1987

Self-expanding metallic stents for small vessels: an experimental evaluation.

Thirty-three self-expanding metallic stents were placed in 24 arterial segments of the hind legs and nine arteries of the abdominal viscera in seven dogs. Twelve 5-mm stents, eight 4-mm stents, and 13 3-mm stents were inserted. Follow-up ranged from 4 to 30 weeks. All 4-mm and 5-mm stents were patent at follow-up. Seven (54%) of the 3-mm stents remained patent. Stent wires were completely covered by a proliferation of the intima. No stent migration, occlusion of side branches, or vessel wall perforation was observed. A stent/artery ratio (SAR) was computed using stent and recipient vessel diameters. Good vascular patency was observed when the SAR was less than or equal to 1.2. An SAR greater than 1.2 was associated with immediate spasm, immediate or delayed thrombosis, or excessive intimal proliferation. Selection of correct stent size is a major determinant of patency in small arteries.

Angiography↗
PubMed1987

Percutaneous endovascular graft: experimental evaluation.

An arterial endovascular graft was constructed by wrapping a Dacron cylinder around the Gianturco expandable metallic stent. The device was passed through an 11-F Teflon catheter into the normal abdominal or thoracic aortas of nine dogs. At follow-up of 7-35 weeks, all but one graft remained patent. At necropsy, the grafts were almost completely covered by neo-intimal proliferation. Similar proliferation was observed between the graft and the wall of the vessel.

Aneurysm↗
PubMed1987

Self-expanding metallic stents: preliminary evaluation in an atherosclerotic model.

The performance of the self-expanding stainless steel (Gianturco) stent in atherosclerotic arteries was examined in a rabbit model. Atherosclerosis was induced by supplementing rabbit chow with 6% peanut oil and 2% cholesterol followed by endothelial disruption of the abdominal aorta with a balloon catheter and continuation on the atherogenic diet for the remainder of the study. Eighteen stents, 1 cm in length and 4 or 5 mm in diameter when fully expanded, were placed in atherosclerotic stenotic lesions in six rabbits. Luminal distention was consistently achieved. At 8 weeks follow-up, no luminal narrowing, stent migration, thrombus formation or branch vessel occlusion had occurred. Atherosclerotic neointimal proliferation occurred around the stent wires following placement, but did not cause significant luminal narrowing.

Animals↗
PubMed1987

Hepatic arterial flow distribution with hepatic neoplasms: significance in infusion chemotherapy.

Hepatic artery radionuclide flow studies and hepatic angiography in eight patients with various hepatic neoplasms were evaluated to determine the patterns of arterial flow distribution in the presence of portal vein occlusion. Increased hepatic arterial blood flow to the lobe or segment supplied by the occluded portal vein was observed in all patients. This phenomenon must be taken into account when positioning catheters for hepatic artery infusion chemotherapy; while it may improve the flow of chemotherapeutic agents to tumors located in the area of an occluded portal vein branch, it may also result in diversion of flow to the normal hepatic parenchyma away from tumors occupying the hepatic segments with patent portal venous flow. Hepatic angiography and radionuclide flow studies provide the necessary information for correct positioning of hepatic artery infusion catheters.

Adenocarcinoma↗
PubMed1987

Experimental combination chemotherapy: intracarotid versus intravenous administration of aziridinylbenzoquinone, BCNU, and cisplatin in dogs.

Sixteen adult beagles (10-12 kg) were used to evaluate combinations of 2,5-diaziridinyl-3,6-biscarboethoxyamino-1,4-benzoquinone (AZQ, aziridinylbenzoquinone), 1,3-bis-2-chloroethyl-1-nitrosourea (BCNU, carmustine), and cis-dichlorodiammineplatinum(II) (CDDP, cisplatin) administered by intravenous or intracarotid infusion. Moderate to severe systemic toxicities resulted from all drug infusions, but no histopathologic changes were found in the central nervous system (CNS) of any of the dogs. Results indicated that the toxicities were not dependent on the route of administration or the recipient's gender, and they were reversible in most cases with intravenous supportive therapy. Cisplatin seemed to have an additive effect when administered in combination with AZQ and/or BCNU.

Animals↗