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Biomedical subjects

S M Taylor

Publications and source records attributed to S M Taylor.

At least 127 records · Page 7Linked to original sources
PubMed1994

The utility and durability of vein bypass grafts originating from the popliteal artery for limb salvage.

BACKGROUND: Short vein grafts originating from sites distal to the common femoral artery have been reported to be useful in selected patients with tibial artery disease. From 1987 to 1993, we performed 504 consecutive infrainguinal vein bypass grafts, of which 56 (11%) originated from the popliteal artery, 25 above and 31 below the knee. PATIENTS AND METHODS: The patients were 16 women and 37 men, with a mean age of 62.4 years. Eighty-seven percent were diabetic, 57% had clinically obvious coronary artery disease, and 28% had end-stage renal disease (ESRD). The indication for surgery was ulceration or gangrene in 93% of cases. We preferentially used reversed greater saphenous vein harvested from the thigh to optimize conduit quality and avoid lower leg wound complications. The outflow artery sites were: dorsal pedal (17), posterior tibial (14), peroneal (10), anterior tibial (8), lateral or medial plantar (5), and sequential tibial (2). All patients were followed postoperatively with serial duplex surveillance. The mean follow-up was 12.5 months (range 1 to 66). RESULTS: In-hospital mortality was 5.4%. Mortality at 24 months was 19% overall and 38% in patients with ESRD. Limb salvage was 77% at 3 years, 92% in patients with normal renal function versus 59% in those with ESRD (P < 0.003). Primary graft patency by life-table analysis was 94% at 1 month and 84% at 3 years. Five patients with patent grafts required amputation, 4 early and 1 late. Eight months after surgery, 1 patient (1.8%) developed superficial femoral artery stenosis which was diagnosed by duplex surveillance and successfully treated by percutaneous transluminal balloon angioplasty. CONCLUSIONS: Vein bypass grafts originating from the popliteal artery are effective and durable. Proximal disease progression rarely poses a significant threat to long-term graft patency. Patients with ESRD, blind tibial outflow tracts, and extensive forefoot lesions appear to be at increased risk of limb loss even with continued graft patency.

Adult↗
PubMed1994

Does infrapopliteal arterial runoff predict success for popliteal artery aneurysmorrhaphy?

BACKGROUND: A 6-year experience with surgical management of popliteal artery aneurysms (PAAs) was examined to determine the influence of infrapopliteal outflow vessel patency on the long-term success of popliteal artery aneurysmorrhaphy. METHODS: Arteriograms were reviewed to characterize the anatomy of the infrapopliteal arterial runoff. Regular clinical evaluation and prospective serial duplex scan surveillance assessed graft patency. RESULTS: A total of 28 patients underwent 45 popliteal aneurysmorrhaphies. Elective repair was performed in 32 limbs (71%); emergency treatment was needed for 13 limbs (29%) because of acute limb-threatening ischemia. All patients were managed with PAA exclusion and reversed saphenous vein grafting. Only 20 limbs (44%) had a patent trifurcation with three continuous vessels to the ankle, 13 (29%) had two continuous tibial vessels, 10 (22%) had one patent runoff artery, and 2 (4%) had no vessel continuous to the foot. With a mean follow-up of 19.1 months, the 5-year primary graft patency by life-table analysis was 95 +/- 12.3%, with a 5-year assisted primary patency of 97 +/- 10.0%. One vein graft underwent elective secondary revision. Another graft thrombosed, requiring a secondary bypass. Outcome did not correlate with the status of the runoff anatomy. Limb salvage was 100%. CONCLUSION: The use of autologous reversed vein grafting and attention to technical details yielded normal graft hemodynamics and excellent long-term patency and limb salvage despite the suboptimal runoff anatomy associated with PAAs.

Aged↗
PubMed1994

Long-term follow-up of patients with Roux-en-Y gastrojejunostomy for gastric disease.

OBJECTIVE: A consecutive series of Roux-en-Y gastrojejunostomies with a mean follow-up of 11.9 years was reviewed to characterize the long-term results of patients having this operation to treat or prevent bile reflux gastritis. SUMMARY BACKGROUND: Development of postprandial abdominal discomfort, nausea, vomiting, or bezoar formation (Roux stasis syndrome) in the postoperative follow-up period has prompted questions about the role of Roux-en-Y gastrojejunostomy to treat or prevent bile reflux gastritis. METHODS: Long-term clinical follow-up (mean, 11.9 years) data for 24 patients was collected by reviewing medical records, interviewing patients directly through telephone contact, or both. All patients who had symptoms in the follow-up period were evaluated by upper gastrointestinal series, endoscopy, or both. A modified Visick scale was used for clinical ratings. RESULTS: Of the 22 evaluable patients, follow-up was complete in 20; the clinical condition that prompted surgery was corrected in 21 (95%). Roux-en-Y gastrojejunostomy was successful for treating or preventing bile reflux gastritis in all 22 patients. Despite this success, clinical failure (Visick scale III or IV) was documented in 8 patients (36%). Seven of the 8 patients had clinical failure within 6 months of operation, with the Roux stasis syndrome developing in 6 of them (27%). CONCLUSION: This consecutive series of Roux-en-Y gastrojejunostomies performed by one surgeon has the longest follow-up to date. Although the Roux-en-Y gastrojejunostomy is safe and often successful, the procedure appears to be limited by a substantial rate of clinical dissatisfaction. Surgeons should be cautious in using it to treat primary or remedial gastrointestinal disease.

Adult↗
PubMed1994

Effect of depth upon the smoothness of excimer laser corneal ablation.

The Argon Fluoride (ArF) Excimer laser is currently used for experimental reshaping of the front surface of the cornea for the correction of myopic refractive error (photorefractive keratectomy, PRK) and for smoothing corneal irregularities (phototherapeutic keratectomy, PTK). Both PRK and PTK are in FDA clinical trials, but are more readily available outside the U.S.A. These techniques have achieved reasonable success in spite of early reports that deeper ablation procedures can cause reduced corneal clarity (haze) or a result which is less accurate or tends to regress. We studied how different depths of excimer tissue removal affect the smoothness of the ablation zone of the rabbit cornea. Dutch belted rabbits were immediately sacrificed by pentobarbital overdose. Their corneas were de-epithelialized with a knife or by the excimer laser and then were photoablated. A 4.5-mm circular ablation beam was delivered to each denuded area, but the beam was masked by positioning a steel blade to partially block the laser beam, thus creating variable ablation depths corresponding to 0.0, 12.5, 37.5, and 62.5 microns. The eyes were fixed in situ by topical and anterior chamber application of glutaraldehyde and the corneas were excised after 5 min and placed in glutaraldehyde for tissue processing. The corneas were whole-mounted and examined by scanning electron microscopy (SEM). The resultant micrographs show increasing irregularity of the ablated surface as a function of depth. The irregularity appeared to be due largely to the inhomogeneities of the anterior stroma, which is known to be layered by alternately directed collagen fibrils.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effect of corneal edema upon the smoothness of excimer laser ablation.

We studied the effect of corneal hydration upon ablation rate in excimer laser photorefractive keratectomy (PRK). This variable may alter the subepithelial smoothness and the resulting clarity of the result. The eyes of freshly slaughtered pigs (N = 5) and the eyes of Dutch-belted rabbits (N = 4) (in vivo) were de-epithelialized and central ablation zones 3.0 to 4.5 mm in diameter were produced in the subepithelial corneal layers using a 193 nm argon fluoride (ArF) ophthalmic excimer laser. Ablation was performed immediately or after a 15-min incubation period in distilled water as a means of inducing corneal edema. Smoothness was evaluated using specular reflection microscopy and showed the water-treated surface to be increasingly less regular than the nonwater-treated samples. Water treatment may affect the final outcome of the PRK procedure and indicates the need to monitor the preoperative cornea for the development of any edema, especially after the epithelium is removed.

Animals↗
PubMed1994

The geographic variation of cancer incidence in Ontario.

OBJECTIVES: Our objectives were (1) to describe an analysis of the spatial pattern of cancer incidence in Ontario and (2) to discuss the quality of data in the Ontario Cancer Registry with respect to the accuracy of local cancer rates. METHODS: Cancer incidence rates were calculated for 22 cancer sites in 49 counties of Ontario during 1976 to 1986. Capture-recapture methods were used to estimate completeness of case registration, and completeness of residence information was also assessed. Spatial autocorrelation was used in measuring the geographic pattern of incidence rates. Comparisons were also made between sexes and with earlier data from 1966 to 1975. RESULTS: The quality of the geographic data in the registry appeared good, and corrections for incomplete or inaccurate registration had little impact. About one third of the sex-site combinations showed some evidence of spatial patterning in the cancer rate. Particularly strong regional variation was noted for cancers of the stomach, lung, uterus, and prostate. CONCLUSIONS: The analysis revealed a number of cancers with significant spatial patterning of risk. Further work is needed to relate the cancer data to other information on potential life-style and environmental factors.

Female↗
PubMed1993

Mouse cDNAs encoding a trifunctional protein of de novo purine synthesis and a related single-domain glycinamide ribonucleotide synthetase.

Three of the enzymatic activities of de novo purine synthesis, glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS) and glycinamide ribonucleotide formyltransferase (GART), can be catalyzed by a single 110-kDa protein in mouse cells. Western blots using a polyclonal antibody (Ab) to this protein identified two species, the trifunctional 110-kDa protein and a 50-kDa cytosolic protein with GARS, but not GART activity. We used Ab and, subsequently, oligodeoxyribonucleotide screens to isolate cDNAs corresponding to these two proteins from mouse T-cell cDNA expression libraries. The sequence of one class of these cDNAs and the partial sequence of a corresponding genomic clone defined an open reading frame (ORF) encoding a 1010-amino-acid (aa) protein, individual domains of which showed high homology to each of the monofunctional bacterial GARS, AIRS and GART proteins, and to each domain of chicken and human trifunctional GARS-AIRS-GARTs. cDNAs corresponding to the smaller protein contained a 1.3-kb ORF with complete identity to the GARS domain of, but with a 3' untranslated region different from, the trifunctional cDNAs. Hence, both cDNAs appear to derive from the same gene due to either differential splicing or use of an intronic polyadenylation signal. The functional requirement for the expression of both trifunctional protein with GARS activity and monofunctional, catalytically active GARS is unknown.

Acyltransferases↗
PubMed1993

Efficacy, pharmacokinetics and effects on egg-laying and hatchability of two dose rates of in-feed fenbendazole for the treatment of Capillaria species infections in chickens.

Laying broiler breeder hens infected with Capillaria obsignata were treated with in-feed fenbendazole either at a dose of 30 ppm for six days or 80 ppm for three days. The respective efficacies of treatment were 92.3 and 99.3 per cent. These results were a reflection of the plasma pharmacokinetics of fenbendazole and its metabolites in the regimens, which showed that the detectable plasma concentrations of the anthelmintically active fenbendazole sulphoxide in the second treatment were significantly greater than the first, with the area under the curve 1.34 times that of treatment 1. Both treatments produced a slight decline in egg production, but only the loss in production with treatment 1 was significant. Hatchability of eggs with both treatments was not significantly affected.

Animal Feed↗
PubMed1993

Transplacental and nonplacental clearances of diphenhydramine in the chronically instrumented pregnant sheep.

Pharmacokinetic studies of the histamine H1-receptor antagonist diphenhydramine were conducted in eight chronically instrumented pregnant sheep at 126-138 days of gestation. Diphenhydramine was administered by simultaneous intravenous bolus injection and infusion to steady state given 48 h apart, to the ewe and the fetus on separate occasions. Average steady-state drug concentration in plasma after maternal infusion was 212.1 +/- 67.8 ng/mL in the mother and 36.3 +/- 14.4 ng/mL in the fetus, resulting in a fetal-to-maternal concentration ratio of 0.19 +/- 0.10. Following fetal infusions, maternal and fetal steady-state drug concentrations were 31.1 +/- 11.6 and 447.6 +/- 185.2 ng/mL, respectively. The free fraction of diphenhydramine determined in the fetus (0.277 +/- 0.087) was significantly greater than that in the mother (0.141 +/- 0.079). Transplacental and nonplacental clearances were calculated at steady state according to a general two-compartment open model, with drug elimination occurring from both compartments. The total fetal clearance (472.7 +/- 215.7 mL/min) was relatively small compared with the total maternal clearance (3426.1 +/- 905.8 mL/min). The transplacental clearance from fetus to mother (264.4 +/- 138.7 mL/min) was approximately threefold higher than that from mother to fetus (82.4 +/- 40.5 mL/min). Maternal nonplacental clearance (3343.8 +/- 890.7 mL/min) accounted for 97.8 +/- 1.1% of the maternal total clearance, whereas fetal nonplacental clearance (208.4 +/- 80.4 mL/min) accounted for 45.1 +/- 4.7% of the fetal total clearance. It is concluded that in the fetus both the transplacental and nonplacental pathways are important for drug elimination.

Animals↗
PubMed1993

The "blue-toe" syndrome as a harbinger of impending infrainguinal vein graft failure: a report of three cases.

Spontaneous "blue-toe" syndrome classically results from distal lower extremity microembolization of intraluminal atheromatous debris from a proximal source to the digital end arteries. During a 6-year period, 274 consecutive infrainguinal reversed vein arterial reconstructions were performed; in three patients (1.1% incidence), atypical distal microembolization originating from focal preocclusive intraluminal vein graft stenoses was identified. Sudden, spontaneous onset of ipsilateral blue-toe syndrome occurred at intervals of 4 to 11 months. Subsequent duplex scans and arteriography demonstrated patent grafts with high-grade, hemodynamically significant focal proximal short-segment sclerotic vein graft stenosis (n = 1) and midgraft valvular weblike stenoses (n = 2) with luminal irregularity. No other associated tandem lesions in the proximal or distal arterial tree were noted that would account for the microembolic phenomenon. The stenotic vein segments were excised with interposition vein graft replacement (n = 1) or with primary end-to-end reanastomoses (n = 2), resulting in complete resolution of the distal microembolic events without need for amputation. Histologic examination of these graft lesions demonstrated significant focal myointimal hyperplasia with adherent platelet aggregates and organized thrombus. The clinical presentation of distal lower extremity cutaneous digital ischemia consistent with microembolization developing ipsilateral to a previously placed vein conduit arterial bypass may signify a "failing" graft with a source from a preocclusive lesion. This finding should prompt aggressive evaluation and immediate revision to maintain assisted primary graft patency and prevention of tissue loss.

Blood Platelets↗
PubMed1993

Proximal anastomotic failure following infrarenal aortic reconstruction: late development of true aneurysms, pseudoaneurysms, and occlusive disease.

Distal anastomotic failure of aortic reconstructions attributable to femoral pseudoaneurysm or outflow stenosis has been well described, but little is known about proximal aortic anastomotic graft failure. A retrospective review was performed between January 1987 and March 1992 to characterize the presentation and management of proximal aortic anastomotic failure. Of 329 consecutive aortic reconstructive operations during this period, 11 (3.3%) were performed to correct complications arising at or adjacent to the proximal anastomosis of an aortic prosthesis. These included anastomotic pseudoaneurysm (n = 6), true aneurysmal dilatation of the residual infrarenal or suprarenal aorta (n = 4), and stenosis of the residual infrarenal aorta (n = 1). The 11 patients had undergone prior infrarenal aortic reconstruction for either aneurysmal (n = 5) or occlusive (n = 6) disease an average of 120 months (range 36 to 175 months) before detection of proximal para-anastomotic graft failure. Eighty-two percent (n = 9) of the proximal lesions were asymptomatic and were discovered incidentally during unrelated medical evaluations. Excluding the six pseudoaneurysms, four of the remaining five lesions developed in a relatively long segment of residual infrarenal aorta, including aneurysm above the graft (n = 2), aneurysm below a proximal end-to-side anastomosis (n = 1), and progressive proximal aortic atherosclerosis (n = 1). Tube graft replacement of the proximal lesions was the most frequently performed operation (n = 7); renal artery reimplantation or bypass was necessary in five cases (45%). Although there was no operative mortality, significant surgical morbidity occurred in three patients (27%). Proximal aortic graft complications tended to be asymptomatic and difficult to repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Modelling psychosocial effects of exposure to solid waste facilities.

A parallel case study design was used to investigate psychosocial effects in populations exposed to solid waste facilities. Psychosocial effects were defined as a complex of distress, dysfunction and disability, manifested in a range of psychological, social and behavioural outcomes, as a consequence of actual or perceived environmental contamination. This paper presents the results of logistic regression analyses designed to identify determinants of psychosocial effects of exposure. The data come from an epidemiologic survey of residents (N = 696) living within a prescribed radius from each of three solid waste facilities in southern Ontario. The analytical model has three main components: external variables (e.g. individual and exposure-related variables); mediating variables (e.g. social network membership and involvement, general health status measures); and outcome variables (e.g. concern, effects and actions). Results for a series of site specific analyses show that outcome measures can be successfully explained by a combination of external and mediating factors. In general, variables from each of the three main components enter the concern-related models while the action models are clearly dominated by social network variables. Analyses using data from all three sites indicate the explanatory power of site-related characteristics. However, given the number and diversity of variables in the models, there is no support for a simple cause and effect relationship. The implication is that strategies aimed to address and alleviate psychosocial effects need to be specific to the characteristics of the populations in particular settings.

Adaptation, Psychological↗
PubMed1993

Worrying about waste: living close to solid waste disposal facilities in southern Ontario.

As a complement to an epidemiological survey, depth interviews were used to discover the individual level impacts of living close to waste disposal facilities in southern Ontario. The paper begins by describing the nature of the sites and reporting some of the survey findings, which the depth interviews explored. Sample selection and data analysis methods are described. A by-code analysis of the material is presented, emphasizing both within- and between-site differences in type and concern (or impact). Concern varied according to type of exposure and site context. The paper ends with a discussion which relates the study's findings on non-toxic facilities to other research on psychosocial effects, lay reasoning and risk perceptions and assessments.

Adaptation, Psychological↗
PubMed1993

The characteristics and anatomic distribution of lesions that cause reversed vein graft failure: a five-year prospective study.

PURPOSE: The cause of vein graft failure in the intermediate postoperative period (3 to 18 months) has not been well defined. To delineate the incidence, characteristics, and anatomic distribution of lesions that cause graft failure in this critical interval, 227 consecutive infrainguinal reversed vein grafts (IRVGs) constructed at a single institution from July 1986 to December 1991 were prospectively entered into a duplex scan surveillance protocol. METHODS: Duplex surveillance with arteriographic confirmation identified 29 patent, hemodynamically failing IRVGs during a mean follow-up of 22 months (range 1 to 64 months). An additional 18 grafts thrombosed before detection of any underlying abnormality; thrombolytic therapy and repeat operation uncovered the cause of occlusion in 12 of these grafts. The cause of graft failure (failing as well as failed) was therefore clear in 41 (87.2%) of 47 instances. RESULTS: The causes of failure were intrinsic graft stenosis (n = 28; 59.6%), inflow failure (n = 6; 12.8%), outflow failure (n = 4; 8.5%), muscle entrapment (n = 2; 4.3%), and hypercoagulable state (n = 2; 4.3%). The most common intrinsic graft lesion was focal intimal hyperplasia (18 lesions in 16 grafts) in the juxtaanastomotic position, occurring solely in the vein graft itself. It occurred with equal frequency immediately distal to the proximal anastomosis or proximal to the distal anastomosis. Only rarely (n = 5) did this involve the juxtaanastomotic artery. Focal midgraft valvular stenoses (n = 6) and diffuse myointimal hyperplasia (n = 4) were also detected. The peak incidence of graft failure was 4 to 12 months after operation (70% within 12 months, 80% within 18 months). CONCLUSIONS: We conclude that duplex surveillance of IRVGs is warranted by the 21% incidence of potentially remediable graft failure. A significant portion of these failures occur during the intermediate postoperative period (3 to 18 months), usually as a result of focal intrinsic vein graft lesions. With reversed vein conduits, these lesions arise predominantly in the vein graft itself, in the juxtaanastomotic position.

Adult↗