Biomedical subjects

W M Abbott

Publications and source records attributed to W M Abbott.

At least 109 records · Page 6Linked to original sources

PubMed1989

Enhancing the carotenoid content of atherosclerotic plaque: implications for laser therapy.

Selective laser ablation of human atherosclerotic plaque is possible because endogenous carotenoid pigments found in atherosclerotic plaque confer a twofold preferential absorption of laser radiation at 450 to 500 nm. In this study, patients with carotid endarterectomy were pretreated with oral beta carotene to determine if the carotenoid content and therefore laser selectivity of plaque could be increased in vivo. Beta carotene-treated patients had a significant, nearly twofold increase in their plaque carotenoid concentration, which increased from 0.22 to 0.40 microgram beta carotene/mg cholesterol. These results suggest that selective ablation of atherosclerotic plaque may be enhanced by pretreating patients with doses of oral beta carotene for short periods of time.

Aged↗

PubMed1989

Are familial abdominal aortic aneurysms different?

A 9-year prospective study of 542 consecutive patients undergoing operation by one of the authors for abdominal aortic aneurysms was undertaken to define the incidence, clinical behavior, and anatomic characteristics of familial abdominal aortic aneurysms. Eighty-two (15.1%) patients having surgery for abdominal aortic aneurysms were found to have a first-degree relative with an aneurysm, as compared to nine (1.8%) of a control group of 500 patients of similar age and sex without aneurysmal disease (p less than 0.001). Detailed analysis was next performed of the pedigree charts of patients with a positive family history of aneurysm who underwent repair of abdominal aortic aneurysms by all authors over the 9-year study period. This review identified a total study population of 86 families with 209 first-degree relatives with abdominal aortic aneurysms. Clinical and anatomic features of this familial group were compared to those of 460 patients operated on for abdominal aortic aneurysms who had no family history of abdominal aortic aneurysms. Patients with familial abdominal aortic aneurysms were more likely to be women (35% vs 14%), and men with familial abdominal aortic aneurysms tended to be about 5 years younger than the women. There was no significant difference between the patients with nonfamilial and familial abdominal aortic aneurysms in anatomic extent of aneurysmal disease, multiplicity of aneurysms, associated occlusive disease, or blood type. There was a history of aneurysm rupture in 35 of 86 (40.7%) families with familial abdominal aortic aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1989

Long-term results of combined iliac balloon angioplasty and distal surgical revascularization.

Long-term results of combined use of iliac artery percutaneous transluminal angioplasty (PTA) and distal surgical revascularization for the management of multilevel occlusive disease were evaluated over a 12-year period. A total of 79 combined procedures were performed in 75 patients. All patients had tandem occlusive disease, with the inflow lesion felt to preclude a distal revascularization procedure alone. Revascularization was performed for incapacitating claudication in 17 (22%) and limb salvage indications in 62 (78%) cases. A mean resting iliac artery pressure gradient of 29 +/- 11 mmHg pre-PTA was reduced to 0.9 +/- 0.4 post-PTA. Major complications of PTA occurred in five (6%) cases, but four were successfully corrected at the time of the distal surgical procedure without alteration of the operative plan. Infrainguinal operations included 55 femoropopliteal or tibial bypass grafts, 18 femorofemoral grafts, and 6 profundaplasties. Mean follow-up was 43 months. By life table analysis, the 5-year primary patency rate of the distal surgical procedures was 76%; a secondary patency of 88% at 5 years was achieved by various means of reintervention. Mean pretreatment ankle/brachial index of 0.31 +/- 0.14 increased to 0.80 +/- 0.16 after operation (p less than 0.0001). The 5-year limb salvage rate was 90%. There were no operative deaths. We conclude that in carefully selected patients, combined use of iliac PTA and distal surgical reconstruction is effective and durable, safely reducing the extent of surgical intervention while reliably increasing the comprehensiveness of revascularization.

Actuarial Analysis↗

PubMed1989

Regional infusion of urokinase into occluded lower-extremity bypass grafts: long-term clinical results.

The initial outcome, long-term patency rate, and rate of limb salvage were studied in patients after regional urokinase infusion for treatment of thrombosed lower-extremity grafts. Seventy-one infusions were performed in 53 patients. Complete clot lysis occurred in 75% of grafts, with establishment of antegrade blood flow in 66%. Variables that favorably influenced clot lysis and the reestablishment of antegrade blood flow through the graft were a short duration of occlusion and a suprainguinal graft position. The median duration of patency after infusion and adjunctive therapy was 162 days, with 75% limb salvage at 301 days. No statistically significant variables that influenced the length of patency were identified. These long-term patency results are inferior to the reported results in suprainguinal grafts after reoperation. They appear similar to reported results for occluded infrainguinal grafts treated with thrombectomy and patch grafting.

Female↗

PubMed1989

Simultaneous carotid and coronary disease: safety of the combined approach.

Invoking unacceptable operative risks, many institutions have adopted a conservative policy toward carotid stenosis in patients who require cardiopulmonary bypass (CPB). We have continued to apply simultaneous carotid endarterectomy/coronary artery bypass grafting (CEA/CABG) in selected patients, and in order to place operative risk in perspective, our experience with CEA/CABG was reviewed and contrasted with both CEA and CABG performed as isolated procedures. Seventy-one CEA/CABG were performed from 1978 to 1987, with the bulk of the experience (51/71) accumulated over the past 5 years. CEA/CABG was applied when the carotid lesion was severe (greater than or equal to 75% diameter stenosis). Clinical characteristics of patients with CEA/CABG (e.g., presence of unstable angina, left main coronary artery disease, and impairment of ventricular function) suggested these patients were at higher risk for complications when compared to patients with CABG alone. Yet, other factors influencing stroke risk during cardiopulmonary bypass (patient age, duration of CPB time) were similar between patients with CEA/CABG and patients with only CABG. Most complications in patients with CEA/CABG occurred in the early years of the study. Considering the recent (1983-87) patient cohorts of CEA/CABG and isolated CABG, respectively, there was no significant difference in either operative mortality (2.0% as compared to 2.2%) or perioperative stroke (2.0% as compared to 0.6%). Whereas precise patient selection criteria remain undefined, these findings verify the safety of the combined CEA/CABG approach for most patients who require treatment of both lesions.

Aged↗

PubMed1988

Further studies of oligosaccharide recognition by the soluble 13 kDa lectin of bovine heart muscle. Ability to accommodate the blood-group-H and -B-related sequences.

Oligosaccharide recognition by the 13 kDa soluble lectin from bovine heart muscle has been investigated by inhibition of binding of the 125I-labelled lectin to trypsin-treated rabbit erythrocytes. The results indicate that the Type 1 (Gal beta 1-3GlcNAc) and the Type 2 (Gal beta 1-4GlcNAc) backbone structures are the basic recognition units, and that the blood-group-H structure, the blood-group-B structure, the 'B-like' structure [afucosyl-(blood group B)] and the alpha 2-3 sialylated analogues of the backbone structures can also be accommodated and hence are candidate receptor structures for the lectin. A comparison of available inhibition data on six other soluble beta-galactoside-binding lectins (three from human lung and three from rat lung) has shown some common features among these and the bovine lectin, e.g. in general a stronger reaction with N-acetyl-lactosamine than with lactose, and a lack of reaction with 3-fucosyl-lactose and 6-sialyl-lactose. However, there are distinctive features among the lectins, e.g. differences in relative reactions with the blood-group-A structure, and no two of the lectins appear to be identical in their fine specificities.

ABO Blood-Group System↗

PubMed1988

Spontaneous aortic dissection in the presence of coexistent or previously repaired atherosclerotic aortic aneurysm.

Acute aortic dissection occurred in 18 patients who had previously diagnosed atherosclerotic aneurysms of the thoracic and/or abdominal aorta. These patients were reviewed to assess the clinical course when these two forms of aortic pathology coexist. Patients were grouped according to status of their atherosclerotic aneurysm (previously repaired vs. untreated) and the segments of the aorta effected by the acute spontaneous dissection. Group 1 patients (n = 5) had previously undergone-abdominal aortic aneurysmectomy (AAA) repair, and the abdominal aortic suture line effectively terminated the dissection process. In Group 2 patients (n = 5), the acute dissection and the atherosclerotic aneurysm involved different segments of the aorta. Group 3 patients (n = 8) experienced spontaneous aortic dissection involving atherosclerotic aneurysms (five infrarenal, three thoracoabdominal), with threatened or actual rupture occurring in six patients, resulting in three deaths. In Group 3 patients, rupture occurred both at the atherosclerotic aneurysm (four patients) and at the site of the aortic intimal tear of the dissection (two patients) after AAA repair. The use of Magnetic Resonance Imaging (MRI) has proven to be highly accurate in delineating the nature and extent of pathology in recently encountered patients with complicated aortic disease. Coexistence of atherosclerotic aneurysm and acute dissection appears to increase the risk of aortic rupture, in both proximal and distal aortic segments.

Acute Disease↗

PubMed1988

Correlation of continuous-wave Doppler spectral flow analysis with gross pathology in carotid stenosis.

Preoperative continuous-wave Doppler spectral analysis was used to generate two parameters, peak frequency in the internal carotid artery (fmax) and the ratio of peak frequencies in the internal and common carotid arteries (carotid index). These were compared with direct measurement of residual lumen diameter in pathologic specimens obtained from carotid endarterectomy in 37 patients. Doppler shift frequency parameters were well correlated with residual lumen diameter when the latter was at least 1 mm. Residual lumens of less than or equal to 2 mm were found to have an fmax of greater than 7.5 kHz and a carotid index of greater than 3.8. If fmax was greater than 14 kHz or the carotid index was greater than 7, the residual lumen diameter was nearly always less than or equal to 1 mm. Thus, the severity of the stenosis correlated directly with Doppler shift frequencies. The length of stenoses did not affect the correlations.

Arteriosclerosis↗

PubMed1988

Prediction of aneurysm formation in vascular grafts of biologic origin.

Other than review of clinical experience, no assay exists that can reliably predict the long-term potential for aneurysm formation in an arterial prosthesis of biologic origin. Since mural degeneration probably results from proteolytic digestion, an in vitro assay was devised that used graft perfusion with 1% collagenase to induce rapid changes in mechanical properties. The effect of enzyme on graft diameter, compliance, permeability, and burst pressure was measured in ficin-digested, adipoyl chloride and glutaraldehyde-tanned bovine carotid artery and glutaraldehyde-tanned human umbilical vein. Both grafts have recently been reported to have a significant incidence of aneurysm within several years of implantation. Compliance and diameter were also measured noninvasively in patients with bovine carotid artery and human umbilical vein for more than 40 weeks after implantation. In vitro, the response to enzyme could be categorized into three groups. In group III, a diameter increase of more than 14% was associated with a significantly decreased compliance, and this paralleled the results found in aneurysmal grafts in vivo. In both grafts there was a strong correlation between postenzyme compliance change and initial compliance, loss of compliance being significantly greater in grafts with group III responses (p less than 0.01). This response may be a good predictor of a graft's overall susceptibility to aneurysmal degeneration, and initial compliance measurement may effectively identify inadequate fixation. Thus measurement of compliance may prove useful in quality control of a fixation process used in mass production. In conclusion, measurement of mechanical properties of biologic vascular grafts before and after collagenase exposure forms the basis for an effective in vitro assay of aneurysm susceptibility.

Aneurysm↗

PubMed1988

Glutaraldehyde release from vascular prostheses of biologic origin.

The inhibition of growth by adult human venous endothelial cells in culture forms the basis of a sensitive assay of glutaraldehyde (GA) concentration, valid between 0 and 5 parts per million. This cytotoxicity assay was used to measure residual (unbound) GA in commercial vascular prostheses of biologic origin following manufacturer-recommended rinsing procedures, from which as much as 13.8 ppm GA per gram of tissue per 24 hours continued to be released after 1 month. A brief (1 hour) exposure of cultured endothelial cells to 2 ppm GA delayed growth, while continuous exposure to 4 ppm totally prevented growth for at least 12 days. Endothelial cells exposed to GA demonstrated a reduced efficiency of attachment to standard test surfaces, although prior GA treatment of these surfaces was not detrimental to subsequent cell attachment. GA release from vascular prostheses may contribute to their lack of endothelial cell coverage in human implants and may be indicative of collagen cross-link instability. If so, in vitro cytotoxicity may be helpful in identifying the potential for aneurysm formation in preserved biologic grafts.

Aldehydes↗

PubMed1988

Immunosuppressive treatment of aortic allografts.

Immunosuppression with cyclosporine (CsA) was explored as a means of preventing arterial allograft rejection and failure. Aortic allografts across the major histocompatibility barrier were studied in Brown-Norway and Lewis inbred rats. Grafts 1 cm long were interposed into the infra-abdominal aorta of Lewis recipients; five groups included two groups of untreated isograft and allograft control animals and three groups had allograft-CsA treatment regimens. The grafts were examined at 30, 60, and 100 days for patency, aneurysmal dilation, gross structural changes, inflammatory responses, and infiltration of W3/25- and OX8-positive lymphocytes. Only three allograft controls became occluded; the rest showed significant dilation (p less than 0.01), medial thinning and necrosis, intimal proliferation, and prominent cellular infiltration at 30 days. With all CsA regimens, aneurysmal dilation was significantly reduced or prevented (p less than 0.01), correlating with medial smooth muscle cell preservation. Cellular infiltration was delayed by an average daily dose of 5 to 10 mg/kg subcutaneous CsA for 30 days and was suppressed at 100 days by a continuous 5 mg/kg dose every 4 days. Intimal thickening in the graft was delayed but not prevented. We conclude that a low maintenance dose of CsA provides effective immunosuppression, thereby preventing aneurysm formation, and that the potential use of arterial allografts in vascular surgery may need to be readdressed.

Animals↗

PubMed1988

Vascular complications associated with spontaneous aortic dissection.

Three hundred twenty-five cases of spontaneous aortic dissection seen at two institutions between 1965 and 1986 were reviewed to assess the incidence, morbid sequelae, and specific management of aortic branch compromise. Noncardiac vascular complications occurred in 33% of the study group, and in these patients the overall mortality rate (51%) was significantly (p less than 0.001) higher than in patients without (29%) such complications. Although aortic rupture was the strongest correlate of mortality (90%), death specifically related to vascular occlusion was common when such occlusion occurred in the carotid, mesenteric, and renal circulation. There was a strong correlation between stroke and carotid occlusion (22/26 cases), yet specific carotid revascularization was only used during the chronic phase of the disease. Similarly, peripheral operation was ineffective in reducing the mortality rate in the setting of mesenteric (87%) and renal (50%) ischemia. Fifteen patients required either fenestration or graft replacement of the abdominal aorta for acute obstruction, rupture, or chronic aneurysm development. Thirty-eight patients (12%) demonstrated some degree of lower extremity ischemia, and one third of these required a direct approach on the abdominal aorta or iliofemoral segments to restore circulation. Selected patients with acute aortic dissection may require peripheral vascular operation in accordance with a treatment strategy that directs initial attention to the immediate life-threatening complications.

Aged↗

PubMed1988

Use of the gastroduodenal artery in right renal artery revascularization.

Of 15 patients having revascularization of the right renal artery with the use of the hepatic circulation from May 1984 through March 1987 at the Massachusetts General Hospital, eight patients had this accomplished with end-to-end anastomosis of the gastroduodenal artery and right renal artery. Operative indications were acute azotemic renal failure (three patients), poorly controlled renovascular hypertension (four patients), and staged repair of bilateral renal artery disease (one patient). All revascularizations were successful in restoring renal function or rendering hypertension manageable and were assessed by means of renal flow scans, celiac angiography, or return of function in those patients with a solitary, functioning kidney. All patients survived the operation with one late death caused by myocardial infarction after abdominal aortic aneurysm repair. The gastroduodenal artery may be used as the source for arterial inflow in revascularization of the right renal artery by end-to-end anastomosis in approximately 50% of instances, conferring the advantage of the use of only one anastomosis and obviating the long-term possibility of vein graft failure.

Anastomosis, Surgical↗

PubMed1987

Amino acid sequence of beta-galactoside-binding bovine heart lectin. Member of a novel class of vertebrate proteins.

A variety of animal tissues contain beta-galactoside-binding lectins with molecular masses in the range 13-17 kDa. There is evidence that these lectins may constitute a new protein family although their function in vivo is not yet clear. In this work the major part of the amino acid sequence of the 13 kDa lectin from bovine heart muscle has been determined. Comparison of this sequence with the cDNA-deduced sequence published for the chick embryo skin lectin showed 58% homology. Comparison of the bovine lectin sequence with partial sequences from two cDNA clones from a human hepatoma library and partial amino acid sequences of human lung lectin showed 70, 40 and 85% homology, respectively. The sequences of these vertebrate lectins are thus clearly related, supporting earlier results of immunological cross-reactivity within this group of proteins. Computer searching of protein sequence databases did not detect significant homologies between the bovine lectin sequence and other known proteins.

Amino Acid Sequence↗

PubMed1987

Adult human vascular endothelial cell attachment and migration on novel bioabsorbable polymers.

We studied the ability of polymers from which vascular prostheses (VPs) are or could be fabricated to support attachment and migration of adult human vascular endothelial cells (AHVECs) in an in vitro system. Polymers included Mylar, Teflon, two novel bioabsorbable polymers with different biologic half-lives (BR1 and BR2), and an elastic nonabsorbable biocompatible polymer (EBN). Both BR1, BR2, and EBN supported AHVEC attachment well (56%, 62%, and 71%, respectively, of plated cells at one hour, respectively) but differed in their ability to support AHVEC migration. The AHVECs attached less well to Mylar and Teflon (39% and 21%), and in no case were AHVECs observed to grow or migrate on either of these polymers. This finding correlates with the clinical observation that VPs fabricated from Mylar and Teflon uniformly fail to develop an endothelial cell lining after implantation in vivo. Future VPs, fabricated from materials chosen for their ability to support AHVEC attachment, growth, and migration in vitro, might better support a spontaneous endothelial cell lining after implantation in humans.

Adult↗

PubMed1987

Neurologic sequelae with internal carotid artery occlusion.

A retrospective review of the clinical course surrounding internal carotid artery occlusion (ICO) was undertaken in 97 patients with 106 instances of ICO. No neurologic symptoms could be attributed to more than half of the ICOs. Of the 52 symptomatic occlusions, 19 (37%) were associated with transient ischemic attacks and 33 (63%) with fixed strokes. Only 10% of all patients had permanent disabling neurologic sequelae. There was no correlation between development of neurologic symptoms and the side of the ICO, the presence or severity of contralateral carotid artery disease, or other risk factors. Women, however, were twice as likely as men to develop a fixed stroke with ICO. Seventy-six of these patients underwent reconstructive carotid surgery. Although there was a high rate of abnormal intraoperative findings with electroencephalographic monitoring (32 of 62 cases), with the use of intraoperative shunts there was no increase in the postoperative stroke complication rate (1.8%). These data suggest that the concern that ICO leads to serious fixed neurologic deficits may be overestimated, and that its presence does not adversely affect carefully performed contralateral carotid endarterectomy.

Aged↗

PubMed1987

Reoperation for aortofemoral graft limb occlusion: optimal methods and long-term results.

To determine optimal methods of reoperation, experience with 157 secondary procedures for unilateral aortofemoral graft limb occlusion in 110 patients during a 16-year period was reviewed. In earlier years, inflow was reestablished by direct replacement of the graft limb or entire graft (11%); more recently, graft limb thrombectomy has been used most frequently (68%) with equal success, durability, and less morbidity. Femorofemoral grafts from the patent contralateral graft limb were employed in 18% of patients, usually those in whom thrombectomy was not attempted. Thrombolytic therapy (3%) appears to offer little advantage, is time-consuming, and occasionally causes significant complications. In addition to reestablishment of inflow, most patients also required revision of the femoral anastomosis to improve profunda femoris runoff; this was usually best accomplished by short segmental extension of the graft limb to the more distal deep femoral artery. Concomitant femoropopliteal bypass was done in 32% of patients and is indicated when preoperative angiography or specific intraoperative findings suggest inadequate profunda femoris outflow. An aggressive approach to reoperation appeared justified by long-term results (mean follow-up 37 months). Despite the need for repetitive reoperation in 26% of patients (two to five reoperations), graft limb patency was ultimately maintained in 78% and limb salvage achieved in 67% of patients, with an operative mortality rate of only 1.9%.

Adult↗

PubMed1987

The evolution of morphologic and biomechanical changes in reversed and in-situ vein grafts.

A comparative study of experimental reversed (RV) and in-situ (INS) vein grafts with respect to the evolution of morphologic and compliance characteristics was done in a canine model. In addition, the compliance characteristics in a series of human INS vein grafts were recorded as a function of time after operation. At 6 months after implantation, all experimental grafts displayed well-developed intimal hyperplasia. There was no significant difference in either absolute intimal thickness (INS 0.133 +/- 0.09 mm vs. RV 0.085 +/- 0.06 mm; NS) nor in the percentage of the total wall thickness occupied by the intima when experimental INS grafts were compared with RV grafts after 6 months. Similarly, compliance values of INS and RV vein grafts were similar at all time intervals examined up to 6 months after operation. Thirty-three human INS vein grafts had a mean compliance value of 1.74 +/- 0.72 (percent radial changes per mmHg X 10(-2) at a median postoperative interval of 14 weeks. This value did not differ significantly from those measured in the INS vein grafts. Although all vein grafts examined retained their native viscoelastic properties, this study suggests that functioning human INS vein grafts are less compliant than previously suspected on the basis of prior ex-vivo and clinical studies of RV saphenous vein grafts. The purported clinical superiority of the INS vein graft cannot be explained on the basis of superior biomechanical performance or failure to develop intimal hyperplasia.

Animals↗