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Biomedical subjects

L M Taylor

Publications and source records attributed to L M Taylor.

At least 109 records · Page 6Linked to original sources
PubMed1991

The association of elevated plasma homocyst(e)ine with progression of symptomatic peripheral arterial disease.

Plasma homocyst(e)ine (the sum of free and bound homocysteine, homocystine, and the mixed disulfide homocysteine-cysteine, expressed as homocysteine) levels were determined by high performance liquid chromatography in 214 patients with symptomatic (claudication, rest pain, gangrene, amputation) lower extremity arterial occlusive disease and/or symptomatic (stroke, cerebral transient ischemic attacks) cerebral vascular disease and in 103 control persons. Mean plasma homocyst(e)ine was significantly higher in patients than in controls (14.37 +/- 6.89 nmol/ml vs 10.10 +/- 2.16, p less than 0.05). Thirty-nine percent of patients (83 of 214) had plasma homocyst(e)ine values greater than control mean + 2 standard deviations. Plasma homocyst(e)ine values were contrasted to age, male sex, diabetes, hypertension, smoking, renal failure, and plasma cholesterol. No difference was found in the incidence and/or level of any of these risk factors when patients with normal plasma homocyst(e)ine were compared to those with elevated plasma homocyst(e)ine, both by univariate and multivariate analysis. Patients with elevated plasma homocyst(e)ine were more likely to demonstrate clinical progression of lower extremity disease and of coronary artery disease, but not of cerebral vascular disease than were patients with normal plasma homocyst(e)ine, and the rate of progression was more rapid (p = 0.002). Progression of lower extremity disease as assessed in the vascular laboratory was also more common in patients with elevated plasma homocyst(e)ine (p = 0.01). We conclude that elevated plasma homocyst(e)ine is an independent risk factor for symptomatic lower extremity disease or cerebral vascular disease or both. Symptomatic patients with lower extremity disease and with elevated plasma homocyst(e)ine also appear to have more rapid progression of disease.

Age Factors↗
PubMed1991

Vascular contractions to serotonin are augmented by cooling.

Human saphenous veins (HSV; n = 17) were obtained at surgery and assayed immediately. The veins were cut into rings, suspended in organ chambers and connected to force transducers for the recording of isometric tension. Tail arteries (RTA) from male Sprague-Dawley rats were similarly prepared. In quiescent rings, cooling from 37 to 24 degrees C had no significant effect. In the presence of alpha-adrenoceptor blockade, potassium chloride (KCl, 10-80 mM) caused concentration-dependent contractions that were inhibited slightly by cooling. Serotonin (5-HT, 10(-8)-10(-5) M) elicited concentration-dependent contractions in both the HSV and RTA with EC50's (-log concentration required to induce contractions 50% of maximal) of 6.31 +/- 0.03 and 6.55 +/- 0.06, respectively. These contractions were subject to blockade with the S2-selective 5-HT antagonist, ketanserin. When either HSVs or RTAs were contracted with 5-HT and cooled, a potent augmentation of the contractions ensued. The data indicate that, while acute moderate cooling does not significantly augment either resting tone or KCl-induced contractions of HSV or RTA, S2-receptor-mediated events are enhanced, yielding potent augmentations of the vascular response to the platelet-derived compound, serotonin. The relationship between temperature and serotonergic receptor responsiveness may be of clinical importance as a mechanism contributing to cold-induced vasospasm.

Animals↗
PubMed1991

Simultaneous operative repair of multilevel lower extremity occlusive disease.

Sixty-two patients (39 men (63%), 23 women (27%), mean age 68 years) with multilevel lower extremity arterial occlusive disease underwent simultaneous inflow and outflow operative arterial repair consisting of aortofemoral bypass in 22 (35%), axillofemoral bypass in 17 (28%), femorofemoral bypass in 15 (24%), iliac endarterectomy in 7 (11%), and unilateral aortoiliac bypass in 1 (2%), combined with 69 outflow procedures (unilateral in 55 patients, 89%), including above-knee femoropopliteal in 12 (17%), below-knee femoropopliteal in 35 (51%), femoroinfrapopliteal in 20 (29%), popliteal tibial in 1 (1%), and femoropedal bypass in 1 (1%). Multiple criteria were used to identify patients with multilevel disease likely to benefit from multilevel procedures. The operations were performed by two operating teams in a median time of 240 minutes. Prosthetic grafts were used for eight (13%) distal bypasses, the remainder were autogenous vein. There was one operative death (1.8%). The mortality rate, morbidity rate, and operative time were not significantly different from a group of patients who underwent concurrent, isolated inflow operations (aortofemoral, axillobifemoral, femorofemoral bypass or iliac endarterectomy). Mean follow-up was 14.9 months (range, 0 to 120). The life-table primary patency for the inflow procedures was 92.6% at 24 months, the outflow was 94.9% at 24 months. Cumulative limb salvage was 90.9% at 48-month follow-up. All patients with claudication were relieved of their symptoms. We conclude that complete correction of multilevel disease can be accomplished with operative time, morbidity rate, and patency equal to that of single level repair. Multilevel procedures provide complete relief of symptoms in a higher percentage of patients than has been reported after single level repair.

Adult↗
PubMed1991

Clinical and anatomic considerations for surgery in femoropopliteal disease and the results of surgery.

From 1980 to 1988 we performed 288 femoropopliteal bypass operations in 231 patients at the Oregon Health Sciences University. The indication for the procedure was claudication in 31% and the relief of limb-threatening ischemia in 64%. Operative mortality occurred after four of these operations (1.4%), including three deaths from myocardial infarction and one death from stroke. The femoropopliteal bypass patients were divided into groups for patency analysis, including those undergoing bypass surgery with a good quality greater saphenous vein versus alternate bypass conduits and patients undergoing primary limb bypass versus those undergoing repeat bypass after prior bypass failure. Our overall primary graft patency for all femoropopliteal grafts was 79% at 5 years. Patients undergoing bypass with a good quality greater saphenous vein had primary graft patency of 85% at 5 years. Patients undergoing bypass using a conduit other than greater saphenous vein had a 5-year patency of 73%. Patients undergoing repeat bypass after a prior failed bypass had a 5-year patency of 57%.

Arteriosclerosis↗
PubMed1991

Fifteen-year results of ambulatory compression therapy for chronic venous ulcers.

A nonoperative approach to venous stasis ulceration of the lower extremity, consisting of initial bedrest, ulcer cleansing, dressing changes, and ambulatory elastic compression stocking therapy, has been maintained for over 15 years. All patients had class III, severe chronic venous insufficiency. One hundred five of 113 patients (93%) experienced complete ulcer healing in a mean of 5.3 months. One hundred two patients were compliant with elastic compression stockings, and 11 patients were noncompliant. Complete ulcer healing occurred in 99 of 102 patients (97%) who were compliant versus six of 11 patients (55%) who were noncompliant (p less than 0.0001). The influence of noncompliance, previous venous ulceration, previous venous surgery, previous known deep venous thrombosis, peripheral arterial insufficiency (ankle brachial systolic blood pressure index less than or equal to 0.60), pretreatment ulcer duration, ulcer size, age, sex, diabetes, smoking, and photoplethysmography venous refill time on ulcer healing was determined by logistic regression analysis. Only noncompliance with elastic compression stockings (p less than 0.0001) and a pretreatment ulcer duration of more than 9 months (p = 0.02) significantly decreased initial ulcer healing. Posthealing follow-up was available in 73 patients for a mean of 30 months. Fifty-eight patients (79%) continued to be compliant with stockings; 15 patients were noncompliant. Total ulcer recurrence in patients who were compliant was 16%. Five-year lifetable recurrence was 29%. All patients who were noncompliant had recurrent ulceration by 36 months. Previous ulceration, previous venous surgery, and peripheral arterial insufficiency had no effect on ulcer recurrence (p greater than 0.05).

Adult↗
PubMed1990

Improving survival and limb salvage in patients with aortic graft infection.

A 15-year experience with 38 aortic graft infections, including 15 patients with graft enteric fistulas, is reviewed in order to analyze modern-day surgical results utilizing extra-anatomic bypass and aortic graft excision. Perioperative mortality was 14% during the most recent 7-year interval, which was a notable improvement compared with the earlier time interval (p = 0.06). Extended follow-up of the perioperative survivors demonstrated a 77% cumulative 5-year survival and a 76% cumulative 5-year limb salvage rate. Subsequent axillofemoral graft infection occurred in 22% of survivors and resulted in a significantly higher amputation rate compared with those patients with no axillofemoral graft infection (p less than 0.001). The results suggest good perioperative and long-term survival in patients with aortic graft infection, with excellent limb salvage if subsequent axillofemoral graft infection can be avoided.

Aged↗
PubMed1990

Surgical treatment of distal ulnar artery aneurysm.

In the past 7 years, we have encountered six patients with finger ischemia as a result of digital artery occlusion associated with seven distal ulnar artery aneurysms. Our experience with the management of these patients forms the basis of this report. All patients were men, with a mean age of 29 years, and all experienced repetitive trauma to the involved upper extremity. Each patient presented with the acute onset of cool and painful digits, with no previous history of cold sensitivity or Raynaud's syndrome. None of the patients had any serologic or clinical evidence of autoimmune disease. Angiography revealed occlusion of the ulnar artery on the affected side in two patients and patent ulnar artery aneurysms in the remaining five patients. There was occlusion of multiple common and proper digital arteries in all patients. One patient with bilateral ulnar artery aneurysms underwent operative repair consisting of aneurysm excision and replacement with autogenous vein grafts from the lower extremity. All patients have improved symptoms, and the grafts remained patent over a mean follow-up of 24 months (range: 13 to 57 months). Based on these results, we recommend that excision and grafting be considered for patients with symptomatic patent ulnar artery aneurysms. Selected patients with thrombosed aneurysms with ongoing digital ischemia may also benefit from surgical intervention.

Adolescent↗
PubMed1990

Present status of reversed vein bypass grafting: five-year results of a modern series.

From January 1980 through December 1988, 564 limbs in 434 patients were treated for infrainguinal arterial ischemia. Of these, 516 limbs in 387 patients underwent reversed vein bypass grafting. The remainder were treated by primary amputation (11 limbs, 1.9%) or by prosthetic bypass (37 limbs, 6.4%). The indications for operation were limb salvage in 80% of limbs and claudication in 20%. Adequate ipsilateral greater saphenous vein was available for 285 (55%) grafts, with reversed vein bypass achieved in the other 231 operations by use of distal graft origins (151 grafts), use of alternate vein sources (120 grafts), and splicing of venous segments (81 grafts). Seventy-six grafts (15%) were to the above-knee popliteal artery, 199 grafts (37%) were to the below-knee popliteal artery, and 241 grafts (47%) were to infrapopliteal arteries, 26 of which (11%) were to inframalleolar arteries. The primary and secondary patencies for all grafts at 5 years were 75% and 81%, respectively. Grafts to infrapopliteal arteries had significantly worse primary patency (69%) at 5 years than did grafts to the popliteal artery (77%, above knee; 80%, below knee) and grafts formed of adequate ipsilateral greater saphenous vein had significantly better primary patency (80%) than did grafts performed when this conduit was not available (68%). Secondary patency of all graft categories ranged from 76% to 85%, and there were no significant differences regardless of site of distal anastomosis, source of venous conduit, or site of graft origins. We prefer the use of reversed vein bypass grafting for lower extremity revascularization both because of the excellent patency results and because the technique can be applied to the larger number of patients in our practice who lack intact ipsilateral greater saphenous vein, in contrast to in situ vein bypass procedures.

Amputation, Surgical↗
PubMed1990

The effects of cooling on human saphenous vein reactivity to adrenergic agonists.

Human saphenous veins were obtained at surgery and assayed immediately (n = 10). The veins were cut into rings, suspended in organ chambers, and connected to force transducers for the recording of isometric tension. One ring served as control whereas others were treated with the alpha 1-adrenoceptor antagonist prazosin (3 X 10(-7) mol/L), or the alpha 2-adrenoceptor antagonist rauwolscine (10(-7) mol/L). In quiescent rings cooling from 37 degrees C to 24 degrees C had no significant effect. Norepinephrine (10(-8)-10(-5) mol/L) caused concentration-dependent contractions with an EC20 (-log concentration of norepinephrine required to induce contractions 20% of maximal) = 6.97 +/- 0.10. The contractions were inhibited by prazosin (EC20 = 5.89 +/- 0.17, p less than 0.001) and rauwolscine (ED20 = 5.78 +/- 0.11, p less than 0.001). In control rings cooling potentiated contractions evoked at concentrations of norepinephrine below 10(-6) mol/L and inhibited those at higher concentrations. In rings treated with alpha-antagonists cooling depressed the maximal contractile responses. Contractions to the alpha 1-agonist, phenylephrine (10(-7)-10(-4) mol/L), were inhibited by cooling, whereas those to the alpha 2-specific agonist B-HT 920 (10(-7)-10(-4) mol/L) showed a pattern similar to that seen with norepinephrine. The data indicate that the human saphenous vein possesses both alpha 1- and alpha 2-adrenoceptors postjunctionally, and that both contribute to contractile responses. Cold augments saphenous vein reactivity to norepinephrine by an apparent increase in the responsiveness of alpha 2-adrenoceptors to agonists. The relationship between temperature and adrenoceptor responsiveness may be of pivotal importance in defining the mechanism of cold-induced vasospasm.

Cold Temperature↗
PubMed1990

Clinical results of axillobifemoral bypass using externally supported polytetrafluoroethylene.

Seventy-six axillobifemoral grafts with externally supported polytetrafluoroethylene prostheses were performed since 1983. The indications for operation were absolute (aortic sepsis) in 20 (26%) patients and relative (excessive operative risk or technical difficulty) in 56 (74%) patients. The life-table primary patency for these operations at 4 years follow-up (mean follow-up, 2 years, 4 months) was 85%. We conclude that the patency results achieved in this patient series are sufficiently satisfactory to warrant use of axillobifemoral grafts in an expanded number of patients with high operative risk and need for bypass of aortoiliac occlusive disease.

Aged↗
PubMed1990

Can prosthetic graft infection be avoided? If not, how do we treat it?

Most arterial prosthetic graft infections can be prevented although a few will inevitably still occur. Maintaining a high index of suspicion for graft infection permits prompt diagnosis which provides the opportunity for early surgical management and improved potential for a good result. Aortic graft infection is best managed with extra-anatomical prosthetic bypass through clean tissue followed by graft excision. Results with this surgical approach are improving. Recently, authors advocating in situ grafting for graft enteric fistula as well as others recommending nonresectional therapy for localized prosthetic graft infections, have obtained encouraging results comparable to the best series of more standard excisional therapy. Because prosthetic graft infection remains a difficult surgical problem, any potentially useful management innovations warrant serious consideration and analysis with extended follow-up.

Anti-Bacterial Agents↗
PubMed1990

The importance of routine surveillance of distal bypass grafts with duplex scanning: a study of 379 reversed vein grafts.

To assess the utility of routine duplex surveillance, 379 infrainguinal reversed vein grafts performed at two independent teaching hospitals were prospectively entered into a surveillance protocol from March 1986 through August 1989. An average of 3.2 postoperative duplex graft flow velocity (GFV) measurements per graft was obtained during a mean follow-up interval of 21 1/2 months. Only 2.1% of 280 grafts with GFV measurements greater than 45 cm/sec failed within 6 months of a normal surveillance examination. GFV measurements less than 45 cm/sec in 99 grafts led to arteriography in 75 grafts, identifying 50 stenotic lesions in 48 bypasses (12.6% of series). Inflow lesions were present in 5%, outflow stenoses in 2%, and intrinsic graft stenoses in only 6% of bypasses. Only 29% of grafts identified as failing by duplex scan were associated with a reduction in ankle-brachial index of greater than 0.15. Secondary reconstructions were performed in 48 grafts based on detection of a reduced GFV measurement; all such reconstructions are patent after a mean follow-up of 5 months. Duplex surveillance is more reliable in identification of failing vein grafts than is determination of ankle-brachial index.

Adult↗
PubMed1990

Treatment of failed lower extremity bypass grafts with new autogenous vein bypass grafting.

During the last 9 years we performed 111 bypass procedures for lower extremity ischemia, which occurred after failed infrainguinal bypass grafting. An all autogenous reversed vein bypass was achieved in 103 of 111 operations (93%). Five-year primary and secondary patency of bypasses placed as treatment for one or more failed prior bypass(es) was 57% and 71%, respectively, as compared to 80% and 83%, respectively, for 5-year primary and secondary patency of simultaneously placed first time leg bypasses. Five-year limb salvage for bypass procedures performed as treatment for failed bypass was 90%, which was identical to that achieved for first time bypasses.

Aged↗
PubMed1990

Pathophysiological and parasitological studies on a concurrent infection of Ostertagia ostertagi and Cooperia oncophora in calves.

Calves which had received daily concurrent infections of 2000 Ostertagia ostertagi and 10,000 Cooperia oncophora infective larvae over a 42-day period displayed a range of clinical signs typical of acute parasitic gastroenteritis including inappetence, weight loss, hypoalbuminaemia and diarrhoea. There were consistent and significant depressions in both digestive efficiency and nitrogen retention. Radioisotopic studies revealed marked disturbances in protein metabolism which were associated with high losses of plasma proteins into the gastrointestinal tract. On post mortem examination larval establishment of O ostertagi was seen to be high. The adverse changes were prevented by the prior administration of a morantel bolus.

Animals↗