Biomedical subjects

W S Moore

Publications and source records attributed to W S Moore.

At least 19 recordsLinked to original sources

PubMed2006

Intravascular stapler for "open" aortic surgery: preliminary results.

OBJECTIVES: The aim of this study was to assess the efficacy of a new stapling device using a pig model. METHODS: Straight 12 mm Gore-Tex grafts were inserted end to end into the aorta of 12 pigs. One anastomosis was performed with the stapler and the other using 4/0 prolene sutures and 13 mm needles. The animals were sacrificed at one week, one and three months and all grafts underwent histological examination. Leakage from the anastomoses was assessed in a separate specially designed circulation model using saline as a perfusate. RESULTS: The stapled anastomoses took 1.0+/-0.25 minutes to complete while suturing took 8.5+/-1.5 minutes. There was no difference in the histology between the two types of anastomosis. The leak rate was six times greater at the sutured compared to the stapled anastomosis. CONCLUSION: The use of stapled anastomoses may allow a significant shortening of aortic cross clamping time, reduce anastomotic leakage and may be particularly useful in laparoscopic aortic repair. A randomised trial is required to assess the efficacy of this device.

Anastomosis, Surgical↗

PubMed2006

Quantifying submarine groundwater discharge in the coastal zone via multiple methods.

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. As such, this flow may contribute to the biogeochemical and other marine budgets of near-shore waters. These discharges typically display significant spatial and temporal variability making assessments difficult. Groundwater seepage is patchy, diffuse, temporally variable, and may involve multiple aquifers. Thus, the measurement of its magnitude and associated chemical fluxes is a challenging enterprise. A joint project of UNESCO and the International Atomic Energy Agency (IAEA) has examined several methods of SGD assessment and carried out a series of five intercomparison experiments in different hydrogeologic environments (coastal plain, karst, glacial till, fractured crystalline rock, and volcanic terrains). This report reviews the scientific and management significance of SGD, measurement approaches, and the results of the intercomparison experiments. We conclude that while the process is essentially ubiquitous in coastal areas, the assessment of its magnitude at any one location is subject to enough variability that measurements should be made by a variety of techniques and over large enough spatial and temporal scales to capture the majority of these changing conditions. We feel that all the measurement techniques described here are valid although they each have their own advantages and disadvantages. It is recommended that multiple approaches be applied whenever possible. In addition, a continuing effort is required in order to capture long-period tidal fluctuations, storm effects, and seasonal variations.

Brazil↗

PubMed2006

Characterisation of submarine groundwater discharge offshore south-eastern Sicily.

A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12Ls(-1), which are comparable with the total SGD flux in the basin of 17Ls(-1) obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60m(3)s(-1) per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average (222)Rn activity concentration in seawater varied from approximately 0.1kBqm(-3) to 3.7kBqm(-3) showing an inverse relationship with salinity. The continuous monitoring carried out at the site closest to the coast has revealed an inverse relationship of (222)Rn activity concentration on the tide. The (222)Rn concentrations in seawater varied from 2.3kBqm(-3) during high tides to 4.8kBqm(-3) during low tides, thus confirming an influence of the tide on submarine groundwater discharge. Stable isotopes (delta(2)H and delta(18)O) showed that SGD samples consist up to 50% of groundwater. Geo-electrical measurements showed a spatial variability of the salt/fresh water interface and its complex transformation in the coastal zone. The presented results imply that in the studied Donnalucata site there are at least two different sources of SGD, one superficial, represented by mixed fresh water and seawater, and the second one which originates in a deeper limestone aquifer.

Sicily↗

PubMed2001

Measurement of 224Ra and 225Ra activities in natural waters using a radon-in-air monitor.

We report a simple new technique for measuring low-level radium isotopes (224Ra and 226Ra) in natural waters. The radium present in natural waters is first preconcentrated onto MnO2-coated acrylic fiber (Mn fiber) in a column mode. The radon produced from the adsorbed radium is then circulated through a closed air-loop connected to a commercial radon-in-air monitor. The monitor counts alpha decays of radon daughters (polonium isotopes) which are electrostatically collected onto a silicon semiconductor detector. Count data are collected in energy-specific windows, which eliminate interference and maintain very low backgrounds. Radium-224 is measured immediately after sampling via 220Rn (216Po), and 226Ra is measured via 222Rn 218Po) after a few days of ingrowth of 222Rn. This technique is rapid, simple, and accurate for measurements of low-level 224Ra and 226Ra activities without requiring any wet chemistry. Rapid measurements of short-lived 222Rn and 224Ra, along with long-lived 226Ra, may thus be made in natural waters using a single portable system for environmental monitoring of radioactivity as well as tracing of various geochemical and geophysical processes. The technique could be especially useful for the on-site rapid determination of 224Ra which has recently been found to occur at elevated activities in some groundwater wells.

Environmental Monitoring↗

PubMed2001

Current training and practice of endovascular surgery: a survey.

Endovascular surgery (EVS) has become of great interest to the vascular community. However, little data exist about the current status of training and utilization of EVS, thus prompting this survey. During a national vascular meeting, all participants (n = 132) filled out a 2-page questionnaire. Respondents (mean age 39 years, 87% male) were 68 vascular surgeons in practice (52%), and 64 fellows (48%), representing a significant fraction of trainees in North America. Practice location included university hospital (39%), private hospital/clinic (52%), and government hospital (8%). According to respondents, in their respective communities, most of the EVS was performed by radiologists (66%), followed by vascular surgeons (19%), cardiologists (13%), and vascular medicine physicians (2%). A majority of respondents (75%) currently perform EVS; surgeons in practice < 3 years had the highest rate (90%). Utilization rates among the nine interventions surveyed ranged from angiography (72%) and angioplasty (65%) to intravascular ultrasound (IVUS) (21%) and atherectomy (12%). Procedure totals showed that approximately 20% of fellows performed > 100 angiograms and 10% performed > 25 endovascular grafts/year, whereas nonfellows performed few of the latter. Most of the EVS (72%) was performed in the operating room with portable imaging equipment and EVS accounted for 14% of all vascular procedures. Most respondents (86%) believed that EVS would become a major component of vascular surgery and comprise 30% of their future practice. Seventy-six percent thought their training was insufficient and 85% said they would devote 3 months or less for further endovascular training. In conclusion, a vast majority of vascular trainees and surgeons are performing EVS, however, individual caseloads vary greatly. The belief that endovascular surgery will play an increasing role in vascular surgery practice is strong and interest in further training of short duration is widespread. Broader-based data collection and longitudinal studies on this issue are warranted.

Adult↗

PubMed2001

Combined carotid endarterectomy and coronary bypass: a decade experience at UCLA.

PURPOSE: The purpose of this review was to determine outcomes for combined carotid endarterectomy (CEA) and coronary revascularization (CABG) in patients with asymptomatic carotid stenosis. METHODS: We reviewed the medical records of consecutive combined procedures (CEA and CABG), performed at UCLA Medical Center from October, 1989 to January, 1999. FINDINGS: There were 43 patients, 27 men and 16 women, with a mean age of 71 yr (range 51-87). Thirty-four patients 79% (34/43) had asymptomatic carotid stenosis. Stroke occurred in three patients (3/43 = 6.9%). Stroke ipsilateral to the CEA occurred in two patients: one asymptomatic (1/34 = 2.9%) and one symptomatic (1/9 = 11.1%). CONCLUSIONS: The majority of patients undergoing combined CEA/CABG have asymptomatic carotid stenosis identified in preparation for elective CABG. The asymptomatic carotid subset stroke rate of 2.9% resulting from a combined CEA/CABG is higher than our reported rate for CEA performed alone. In patients with asymptomatic carotid stenosis, the combined procedure should be selectively performed.

Aged↗

PubMed2001

Aorto-uni-iliac endograft for complex aortoiliac aneurysms compared with tube/bifurcation endografts: results of the EVT/Guidant trials.

OBJECTIVE: Our objective was to present the results of the multicenter EVT/Guidant aorto-uni-iliac trial and to compare them with the tube, bifurcated graft, and open control series in regard to patient demographics, medical comorbidity, 30-day morbidity/mortality, and outcome at 1 year. METHODS: One hundred twenty-one patients not eligible for tube or bifurcated endografts were entered into the aorto-uni-iliac trial (A-I). These were compared with 153 patients in a tube (T) group, 268 patients in a bifurcated endograft (BI) group, and 111 patients in an open control (C) group. All data were audited and independently analyzed for presentation to the Food and Drug Administration. RESULTS: Group demographics were similar with the following exceptions. Aneurysm diameter was significantly less in the T group (51.2 mm) but similar for the A-I (57 mm), BI (54.6 mm), and C (55.6 mm) groups (P < .001). There were more male patients in all endograft groups (A-I 92.6%, BI 89.5%, T 85.6% vs 76.6% for C, P = .002). Peripheral arterial occlusion was present more frequently in the A-I group (25.6% vs 13.8% BI, 10.5% T, and 10.8% C, P = .003). However, no differences were found in mean age, incidence of coronary artery disease, and American Society of Anesthesiologists III/IV classification. Implantation was achieved in 94.2% of the A-I group, 90.3% of the BI group, and 92% of the T group. No significant difference was seen in the operative mortality rate (4.2% A-I, 2.6% BI, O% T, 2.7% C). Postoperative cardiac complications were similar for the A-I (22%) and C (20.7%) groups but significantly less for the BI and T groups (13.4% and 10.5%, P = .019), whereas pulmonary problems were significantly reduced in all endograft groups (A-I 11.9%, BI 10.1%, and T 7.2% vs 22.5% for C, P = .002). Transient renal dysfunction occurred in 6.8% of the A-I group and 8.2% of the BI group but in only 3.3% of the T group and 1.8% of the C group (P = .028). Operating time was significantly longer for the A-I group than for the BI, T, or C groups (258 minutes vs 156, 179, and 174 minutes). Median blood loss, intensive care unit use, and hospital stays were markedly and significantly reduced in all endograft groups compared with the control group. The incidences of type I endoleak at 1 year were 2.4% A-I, 2.3% BI, and 3.8% T, and no ruptures occurred in any of the patients treated with endografts. No femoral-femoral graft thromboses occurred in the A-I group. CONCLUSION: Despite the fact that patients with combined aortic and iliac aneurysms have a more complex repair requirement and have an increased rate of comorbidity, the results are competitive with endovascular repair of aortic aneurysm by tube and bifurcated graft systems and are associated with a lower morbidity than open operation.

Aged↗

PubMed2001

Endoleaks following endovascular repair of abdominal aortic aneurysm: the predictive value of preoperative anatomic factors--a review of 100 cases.

OBJECTIVE: The failure to maintain a secure exclusion of aortic aneurysms with intraluminally placed grafts has been termed endoleak. We performed a retrospective review of our first 100 transluminally repaired abdominal aortic aneurysms (AAAs) in an effort to identify preoperative factors that could predict which patients would have endoleaks. METHODS: Between February 1993 and September 1998, 100 infrarenal aneurysms were treated with tube (39), bifurcated (45), and aortoiliac grafts (16). Endoleaks (early and late) developed in 34 patients. Preoperative computed tomography scans and angiograms for all patients were individually inspected by a single reviewer. Aortic characteristics analyzed included number of patent lumbar arteries, presence of a patent inferior mesenteric artery (IMA), calcification and thrombus at proximal and distal attachment sites, proximal aortic angulation, and graft-vessel size discrepancy at proximal and distal attachment sites. The prevalence of the preoperative factors was compared among patients with and without endoleaks. RESULTS: Endoleaks developed in 44% of tube, 33% of bifurcated, and 47% of aortoiliac grafts (P =.51). Correlation between total number of patent lumbar arteries, presence of a patent IMA, and endoleaks was not significant (P =.44,.95). Calcification at either proximal or distal attachment site did not increase the risk of endoleaks (P =.50,.62). The presence of thrombus at the attachment site (proximally or distally) also failed to increase endoleak rates (P =.12,.78). Degree of proximal aortic angulation did not differ between groups (P =.39). Size discrepancies between graft and aorta or iliac vessels at proximal or distal sites did not significantly differ (P >.54, >.13). Subgroup analysis of endoleaks with different tube types also failed to demonstrate significant differences among the three graft types (P >.05). CONCLUSION: Endoleaks develop in a significant number of endovascularly repaired AAAs. We were unable to demonstrate a statistically significant association with anatomic characteristics thought to predispose to the development of endoleaks. We find no predictive value associated with these anatomic factors.

Angiography↗

PubMed2001

Carotid endarterectomy with normal findings from a completion study: Is there need for early duplex scan?

OBJECTIVE: The objective of this study was to determine the value of early (< 6 months) duplex scanning after carotid endarterectomy (CEA) with an intraoperative completion study with normal results. Attention was paid to restenosis rates and reoperation for recurrent stenosis within the first 6 months. METHODS: A retrospective review was performed on 380 CEAs (338 patients) with intraoperative completion studies and duplex surveillance within the first 6 months. Results of completion studies, restenosis rates, and recurrent symptoms were evaluated for each operation. Studies were performed from 0 to 200 days postoperatively (median, 28). RESULTS: Intraoperative completion studies included 333 angiograms, 26 duplex scans, and 21 angiograms with duplex scans. Of the 380 intraoperative completion studies, 28 (7.5%) had abnormal findings, including 14 abnormal internal carotid arteries (ICAs). Twenty-four procedures were revised, and the findings of all repeat completion studies were normal. Of the initial completion studies, in four cases, abnormalities (3 ICAs) were insignificant and did not warrant further intervention. Follow-up ICA duplex scans had normal results after 364 (95.8%) CEAs. There were 14 mild recurrent ICA stenoses and two moderate recurrent ICA stenoses; neither had abnormal findings from the completion study. There were no severe recurrent ICA stenoses. External carotid artery (ECA) recurrent stenosis included 7 mild, 15 moderate, and 9 severe restenoses. CONCLUSIONS: Only 0.5% of CEAs developed moderate restenosis. No procedures had severe recurrent stenosis on duplex scan within the first 6 months, and none required intervention. Duplex surveillance in the first 6 months is relatively unproductive, providing that there were normal results from an intraoperative completion study for each patient. Routine surveillance can be started at 1 year.

Adult↗

PubMed2001

Acute arterial thrombosis causes endothelial dysfunction: a new paradigm for thrombolytic therapy.

PURPOSE: The goals of this study were to delineate the time course of endothelial dysfunction after arterial thrombosis, to determine the cause of endothelial dysfunction in this setting, and to determine whether modulating standard thrombolytic therapy would ameliorate the thrombosis-mediated endothelial dysfunction. METHODS: Male adult rats underwent infrarenal aortic occlusion by means of clip ligature to induce arterial thrombosis. After 30 minutes, 1, 2, and 3 hours, ring segments from the infrarenal aorta were harvested and placed into physiologic buffer baths. With the use of a force transducer, both endothelial-dependent relaxation (EDR) and endothelial-independent relaxation (EIR) were measured. Endothelial function and presence were determined by means of factor VIII immunohistochemical staining. Endothelial morphology was evaluated with scanning electron microscopy (SEM). Nitric oxide (NO) levels were determined with a chemiluminescent assay of its nitrite/nitrate metabolites (NO(x)). Standard thrombolytic therapy with urokinase (UK) was infused into thrombosed aortic ring segments and compared with UK supplemented with both low-dose L -arginine (2 mmol) and high-dose L -arginine (20 mmol). RESULTS: Arterial thrombosis decreases EDR. The nadir of EDR occurs 1 hour after thrombosis (mean +/- SE, 13% +/- 6.4% vs 94% +/- 2.6% for controls, P <.005), with persistent lowering of EDR as long as 3 hours after thrombosis. EIR is preserved, and vasoconstriction with norepinephrine or potassium buffer is unaltered. Both endothelial function and presence (n = 6 per group) were documented by means of factor VIII immunohistochemistry. An intact monolayer of endothelium at all time intervals after thrombosis was revealed by means of SEM analysis. No differences between control and thrombosed specimens were revealed by means of the grading of SEM images. Local NO(x) levels were lower after 1 hour of thrombosis, with an increase higher than baseline values at 3 hours. The addition of low-dose L -arginine resulted in a minor increase in EDR. However, high-dose L -arginine resulted in a significant increase in EDR versus controls receiving UK alone (64% +/- 6.3% vs 38% +/- 4.4%, P <.05). Correspondingly, local NO(x) levels were 20-fold higher after the high-dose L -arginine supplementation when compared with UK thrombolysis alone (2.8 +/- 0.52 micromol/L vs 0.133 +/- 0.02 micromol/L, n = 6 samples/group, P <.005). CONCLUSION: Acute arterial thrombosis causes endothelial dysfunction, without causing endothelial cell loss. Endothelial function reaches a nadir after 1 hour of thrombosis. EIR and vasoconstriction remain unaffected, indicating normal smooth muscle cell function. NO(x) levels suggest that NO levels are decreased acutely after thrombosis. Supplementing standard thrombolytic therapy with the NO precursor, l-arginine, ameliorates the endothelial dysfunction seen after acute thrombosis by increasing local NO production.

Acute Disease↗

PubMed2001