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Biomedical subjects

N A Scott

Publications and source records attributed to N A Scott.

At least 73 records · Page 4Linked to original sources
PubMed1995

Distal embolization is common after directional atherectomy in coronary arteries and saphenous vein grafts.

Coronary embolization is a complication of coronary intervention procedures. The incidence, predictors, and clinical significance of this phenomenon during directional atherectomy were examined in 111 consecutive patients who underwent directional atherectomy to 120 lesions. Distal embolization occurred in 31 (28%) of the patients. It was noted mainly in the saphenous vein graft group of patients (12 [48%] of 25) versus the native coronary group (19 [22% of 86]; p = 0.01). Clinical predictors were age and de novo lesions. Morphologic predictors were larger artery size, larger postprocedure minimal luminal diameter, calcific lesions, and type C lesions. The only difference in clinical outcome was a longer hospitalization in the distal embolization group with 3.9 +/- 3.7 days versus the rest of the patients 2.4 +/- 2.4 days (p = 0.01). In the majority of patients there was no significant adverse clinical outcome.

Atherectomy↗
PubMed1995

Seeding of vascular grafts with an immortalized human dermal microvascular endothelial cell line.

Small-caliber vascular grafts (< 6 mm) for arterial bypass frequently fail owing either to acute thrombosis or long-term fibrosis. One strategy to enhance patency is the coverage ("seeding") of luminal polymeric graft surfaces with endothelial cells (EC), which may in themselves be thromboresistant and antiproliferative, or which could be transfected with genes whose products are thrombolytic or growth-inhibitory. Advances in understanding of EC-biomaterial interaction have led to improvements in cell coverage and retention, but the sources of EC for such procedures have been limited to large vessels (autologous veins) and microvascular endothelium isolated from autologous adipose tissue. Before the practice of graft seeding can gain widespread clinical acceptance, the practical constraints of EC harvest, EC culture, and quick access to the seeded prosthesis for the surgical procedure must be overcome. Ideally, an EC line with a high proliferative capacity could be preestablished on the grafts, which could then be cryopreserved and made available as needed. The authors have seeded Dacron graft material with an immortalized human dermal microvascular EC line, HMEC-1. These cells were initially transfected with simian virus 40A large T antigen and have been passaged more than 100 times without signs of senescence. They also express von Willebrand factor, take yp acetylated low density lipoproteins, and rapidly form tubes when cultured on matrigel. Confluent coverage of Dacron graft segments, either untreated or coated with gelatin, was achieved in two weeks. The cells formed a monolayer over topographically elevated regions or appeared to be > one layer thick in other areas. Cells were also shown to remain viable after freezing.2+These results suggest a potential practical method for

Blood Vessel Prosthesis↗
PubMed1994

An evaluation of some breeding management options in beef herds in the United Kingdom.

The feasibility of replacing natural service in the suckler herd with artificial breeding (artificial insemination or embryo transfer), following synchronisation of oestrus in breeding animals, was investigated. In 1991 a herd of 143 spring-calving beef cows, matched for date and ease of calving, sex of calf, parity, body condition score and liveweight, were assigned to one of five controlled breeding programmes: natural service (group 1); single oestrus synchronisation using a norgestomet implant and fixed time insemination followed by natural service (group 2); double synchronisation with two consecutive norgestomet implants each with fixed-time insemination followed by natural service (group 3); synchronised as for group 2, but subjected to a movement stress two days after insemination (group 4); and cows synchronised by intravaginal progesterone/prostaglandin regimen with non-surgically transferred in vitro fertilised embryos followed by natural service (group 5). The percentage pregnancy rates to the first and second heats and overall were, respectively: group I, 55.5, 66.7 and 92.6; group 2, 44.4, 71.4 and 89.9; group 3, 52.0, 78.0 and 96.0; group 4, 55.0, 58.3 and 81.5, and group 5, 40.0, 68.2 and 85.7 per cent. In groups 2, 3, 4 and 5 the costs per pregnancy for artificial insemination or embryo transfer were 40.50 pounds, 56.62 pounds, 32.40 pounds and 149.98 pounds, respectively, and the calf weaning weights for groups 1, 2, 3, 4 and 5, adjusted for date of calving, were 250 kg, 255 kg, 252 kg, 261 kg and 259 kg, respectively.

Animal Husbandry↗
PubMed1994

Percutaneous transluminal coronary angioplasty in African-American patients (the National Heart, Lung, and Blood Institute 1985-1986 Percutaneous Transluminal Coronary Angioplasty Registry).

Although black patients have a higher prevalence of risk factors for coronary artery disease, the outcome of coronary angioplasty in black patients is not known. The purpose of this study was to determine if any racial differences existed in the clinical characteristics and outcome of patients enrolled in the 1985-1986 National Heart, Lung, and Blood Institute (NHLBI) Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry. The clinical characteristics, in-hospital event rates, and 5-year follow-up results of all patients enrolled in the 1985-1986 NHLBI PTCA Registry were examined with respect to race. Of the patients enrolled in the registry, 1,939 (90.8%) were white and 76 (3.6%) were black. Among black patients there were more women (50% vs 24%, p < 0.001), and more patients who had hypertension (73% vs 45%, p < 0.001) and diabetes (23% vs 13%, p < 0.05). Black patients were more likely to have multivessel disease (72% vs 48%, p < 0.001). Clinical success rates were similar (76.3% for blacks and 79.3% for whites), but because black patients had more vessels with significant disease, complete revascularization was achieved in 26% of black patients compared with 44% of white patients (p < 0.001). After the PTCA procedure there was no significant difference in major complications (death, myocardial infarction, or emergent coronary artery bypass grafting) between the 2 groups. Five-year follow-up data revealed that there was no significant difference in mortality, myocardial infarction, coronary artery bypass grafting, or repeat PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Black or African American↗
PubMed1994

Incidence and management of catheter-related sepsis in patients receiving home parenteral nutrition.

Fifty patients, comprising 24 male and 26 female of median age 43 (range 15-67) years, received a total of 2620 patient-months of home parenteral nutrition (median 48 (range 2-130) months). There were 13 episodes of bacterial catheter sepsis (of which the catheter was successfully salvaged by an antibiotic-fibrinolytic 'lock' technique in four cases) and ten of exit-site sepsis (all managed by elective catheter replacement), representing an incidence of 1 septic complication per 113 patient-months of parenteral nutrition. This low incidence of catheter-related sepsis was achieved by strict adherence to established protocols of catheter management.

Adolescent↗
PubMed1994

Reconstructive abdominal operations after laparostomy and multiple repeat laparotomies for severe intra-abdominal infection.

Between 1980 and 1993, 18 patients underwent formal laparotomy after laparostomy and healing of the peritoneal cavity by granulation. The majority (12 patients) were men and the median age was 47 (range 22-67) years. Intraabdominal infection following surgery for Crohn's disease (four patients) and necrotizing pancreatitis (six) was the most common primary condition requiring laparostomy. A total of 23 reconstructive operations were carried out on the 18 patients a median of 6 (range 1-18) months after laparostomy. The indication for surgery was for closure and/or resection of an enteric fistula in 13 patients. The site of the fistula included three gastric, two duodenal, 11 small bowel and seven colonic. A further four patients required operation for closure or refashioning of a stoma. Five patients subsequently required a second laparotomy: two for elective restoration of bowel continuity, two for recurrent fistula and one for an acute abdomen. After reconstructive surgery following laparostomy 16 patients were discharged home alive and well, one requiring home parenteral nutrition for short bowel syndrome. In contrast, the two oldest patients in the series died from multiple organ failure immediately after initial reconstructive surgery. Both had pre-existing medical problems and in neither was there evidence of further intra-abdominal infection after reconstruction.

Abdomen↗
PubMed1994

Efficacy and safety of using perfusion dilatation catheter as initial balloon in coronary angioplasty.

The efficacy and safety in using a new low-profile perfusion balloon catheter (PBC) as the initial balloon in percutaneous coronary angioplasty (PTCA) was assessed retrospectively in 61 patients: 43 males, mean age 62 +/- 12 years. Thirty-three patients (54%) had unstable angina. PTCA was performed using an improved PBC in the following vessels: LAD 40%; CX 21%; RCA 24%. Lesion morphology was: Type A 21%; Type B1 18%; Type B2 40%; Type C 21%. Mean artery size was 3.01 +/- 0.53 mm. Mean PBC size was 3.14 +/- 0.45 mm. The mean number of inflations used was 2.85 +/- 2.0. The mean longest inflation was 415 +/- 213 sec and the total inflation time was 663 +/- 342 sec to a mean maximum pressure atmosphere of 7.85 +/- 2.0 bars. The number of balloons used per procedure was 1.2 +/- 0.44. In 50 patients (82%) only one balloon was used during the PTCA. PTCA was successful (< 50% diameter stenosis without major complications) in 60 patients (98.4%). Mean diameter stenosis at baseline was 82 +/- 9.5% and post-angioplasty 13 +/- 10.6%. A mild intimal tear occurred in 6 patients (9.8%). A stent was implanted in 3 patients (4.9%) due to severe dissection. In hospital reocclusion occurred in one patient (1.6%). There were no deaths or emergency bypass surgery. A low profile PBC is safe and effective as an initial balloon in PTCA. It may reduce the number of balloons used and inflations per procedure.

Aged↗
PubMed1994

Effects of cholinergic stimulation and aldosterone administration on salivary parotid secretion in the brushtail possum, Trichosurus vulpecula.

Parotid salivation was stimulated by infusion of bethanechol chloride into anaesthetized brushtail possums to ascertain maximal flow rates, salivary composition and dietary adaptations of salivary function. Secretion rates for one gland ranged from 5.3 +/- 0.16 to 84.3 +/- 3.20 microliters/min (2.4 +/- 0.07 to 37.8 +/- 1.43 microliters/min per kg body weight). Salivary osmolality (160.8 +/- 15.39 to 248.2 +/- 8.70 mosmol/kg) and the concentrations of Na (63.1 +/- 10.93 to 124.1 +/- 5.52 mmol/l) and HCO3 (19.5 +/- 3.41 to 89.0 +/- 3.19 mmol/l) were positively correlated with flow rate. The concentrations of urea (7.8 +/- 0.64 to 4.6 +/- 0.33 mmol/l), PO4 (2.6 +/- 0.25 to 0.96 +/- 0.10 mmol/l), H+ (46.2 +/- 16.30 to 9.0 +/- 1.51 nequiv/l), K (21.4 +/- 3.73 to 13.7 +/- 2.33 mmol/l), Ca (3.7 +/- 0.53 to 2.2 +/- 0.27 mmol/l) and Mg (0.3 +/- 0.07 to 0.04 +/- 0.007 mmol/l) fell with increasing flow rate. The relations between flow rate and amylase activity (22.6 +/- 10.47 to 10.5 +/- 3.68 mu kat/l), protein concentration (2.7 +/- 0.61 to 1.3 +/- 0.28 g/l), and Cl concentration (62.1 +/- 6.88 to 50.6 +/- 6.37 mmol/l) were inconsistent between experiments. Salivary Na/K ratios were not decreased by infusion of aldosterone (2.2-22.2 nmol/h for 5 h), showing that the gland of Na-replete possums is unresponsive to short-term increases in mineralocorticoids. The low salivary amylase activity, less than that of kangaroos, presumably reflects the interaction of evolutionary history of the possum with its natural low-starch diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Local delivery of a synthetic antithrombin with a hydrogel-coated angioplasty balloon catheter inhibits platelet-dependent thrombosis.

OBJECTIVES: This study evaluated the efficacy of local administration of an antithrombin agent with a hydrogel-coated percutaneous transluminal coronary angioplasty balloon catheter. BACKGROUND: Intravenous infusion of antithrombin compounds has been shown to inhibit platelet-dependent thrombosis. However, hemorrhage is a common side effect associated with the systemic administration of antithrombin compounds. METHODS: The potent, irreversible thrombin inhibitor D-Phe-L-Pro-L-Arginyl chloromethyl ketone (PPACK) was used to inhibit thrombus formation in chronic porcine arteriovenous shunts. Platelet deposition was quantitated with gamma camera imaging of 111In-labeled platelets. RESULTS: Intravenous administration of PPACK in swine, in doses sufficient to maximally inhibit thrombus formation, was associated with prolongation of bleeding parameters. The inhibition of thrombosis associated with intravenous PPACK was dose related. The amount of intravenous PPACK necessary for maximal inhibition of thrombus formation for a period of 45 min was 16.9 mg. In contrast, local delivery of PPACK with a hydrogel-coated angioplasty balloon deployed at the site of the thrombus inhibited platelet deposition for at least 45 min after the balloon was removed. Using 3H-labeled PPACK, the calculated amount of PPACK delivered was 33.5 micrograms. There was no change in bleeding time or activated partial thromboplastin time when swine received an intravenous bolus greater than the total amount of PPACK adsorbed onto the balloon (70 micrograms). CONCLUSIONS: These results suggest that in this model, a hydrogel-coated coronary angioplasty balloon catheter can be used to deliver enough antithrombin agent to inhibit platelet-dependent thrombosis for at least 45 min at doses that are several orders of magnitude less than those required for systemic administration. In addition, local delivery can provide effective inhibition of thrombus formation without alteration of bleeding parameters.

Amino Acid Chloromethyl Ketones↗
PubMed1994

Timing of ileocolonic resection for symptomatic Crohn's disease--the patient's view.

Eighty patients were asked if they would have preferred their ileocolonic resection and anastomosis for Crohn's disease, to have been carried out sooner, later or at the same time as it was done. Seventy of the patients replied (88%). No patient would have preferred their operation to have been later, while 74% thought it should have been earlier. A preferred operation time was given for 69 resections, between 0 months--that is, at the same time--and 15 years earlier. The median preferred operation time was 12 months earlier (95% confidence intervals 18 months earlier to 7 months earlier). The remaining 18 patients were satisfied with the timing of their operation. Reasons given for earlier surgery in 58 resections included the severity of Crohn's symptoms preoperatively (97%), the ability to eat normally after resection (86%), feeling of well being after the resection (62%), and abolishing the need for drugs (43%). Patients preferring an earlier operation time were less likely to have had a previous resection (13/58) than patients in the 'same time' group (10/21, chi 2 = 4.746; p < 0.05).

Anastomosis, Surgical↗
PubMed1994

Local delivery of an antithrombin inhibits platelet-dependent thrombosis.

BACKGROUND: Platelet-dependent thrombosis can be effectively inhibited by intravenous administration of direct thrombin antagonists. However, an increased propensity for abnormal bleeding has been associated with systemic administration of these agents. The goal of this study was to determine whether local delivery of a potent thrombin inhibitor, D-Phe-L-Pro-L-Arg chloromethyl ketone (PPACK), could inhibit platelet-dependent thrombosis without altering systemic hemostatic function. METHODS AND RESULTS: Thrombus formation was measured by quantitative imaging of 111In-labeled platelet deposition on segments of thrombogenic vascular graft interposed in arteriovenous shunts in a porcine model. Intravenous administration of PPACK inhibited platelet deposition at a dose of 12.5 micrograms/kg per minute, which was associated with significant prolongations of both template bleeding times and activated partial thromboplastin times. By contrast, local infusion of PPACK at a dose of 0.02 micrograms/kg per minute (ie, a 600-fold smaller dose) into the fluid boundary layer at the interface between flowing blood and the thrombogenic segment produced equivalent inhibition of platelet deposition without prolonging either the bleeding time or the activated partial thromboplastin time. In addition, static exposure of a mural thrombus to solutions of PPACK at concentrations > or = 2.5 mg/mL for 15 minutes produced sustained inhibition of platelet-dependent thrombosis with no change in hemostatic measurements. CONCLUSIONS: These results indicate that local delivery of the direct antithrombin PPACK, by either boundary layer infusion or static application techniques, effectively inhibits platelet-dependent thrombosis at doses that are several orders of magnitude less than the systemic dose required for an equivalent antithrombotic effect. In contrast to the systemic administration of PPACK, local delivery produced maximal inhibition of thrombosis without alterations in hemostasis.

Amino Acid Chloromethyl Ketones↗
PubMed1994

Catheter-related morbidity in patients on home parenteral nutrition: implications for small bowel transplantation.

Until recently, Home Parenteral Nutrition (HPN) has been the only real option for patients with intestinal failure. Small bowel transplantation (SBT) is advancing rapidly, however, and may soon provide an alternative for these patients. One of the arguments in favour of SBT is the alleged morbidity of prolonged parenteral nutrition. We have assessed the catheter-related morbidity in a large cohort of patients on HPN. A total of 88 central venous catheters were required in 50 patients. The main complications were sepsis (24 episodes) and occlusion (18 episodes). The overall incidence of catheter-related morbidity was one episode per 46 patient-months of HPN.

Adolescent↗
PubMed1993

Recent changes in the management and outcome of acute closure after percutaneous transluminal coronary angioplasty.

The major cause of morbidity and mortality associated with percutaneous transluminal coronary angioplasty (PTCA) is acute closure. This study compared the clinical outcome of 2 groups of patients who experienced acute closure during PTCA. One group was treated during a period when intracoronary stents, laser balloons and perfusion balloons were available for treatment of acute closure (group II). These results were compared with the clinical outcome a group of similar patients who were treated for acute closure during a period that immediately preceded the availability of these devices (group I). One hundred sixty-six patients had acute closure in group I, whereas 156 patients experienced acute closure in group II. Baseline clinical characteristics were similar for both groups. There was no difference in ejection fraction, number of vessels diseased, degree of stenosis or number of vessels attempted between the 2 groups. Patients in group II had more balloon inflations and longer balloon inflation times when compared with patients in group I. Of the 156 patients in group II, 47% were treated with either an intracoronary stent, laser balloon or perfusion balloon. Group II patients had fewer Q-wave myocardial infarctions (9.1 vs 20.3%, p = 0.005). In addition, peak creatine phosphokinase levels (826 +/- 1,515 vs 517 +/- 1,050, p < 0.01) and mean residual stenosis (40.7 +/- 33.2 vs 58.0 +/- 34.4%, p < 0.0001) were also lower in group II patients. There was also less coronary artery bypass grafting during the same admission (38.6 vs 29.5%, p = 0.02) in group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Surgical management of perineal and metastatic cutaneous Crohn's disease.

Skin lesions are the commonest extraintestinal manifestation of Crohn's disease. Lesions that develop at sites remote from the gastrointestinal tract and have granulomas on histological examination are termed metastatic cutaneous Crohn's disease. Management is difficult as medical treatment is often ineffective. This report describes the use of surgical debridement of areas of perineal metastatic cutaneous Crohn's disease in five patients, all of whom had failed to improve after a variety of medical treatments. One patient had a poor result with continuing mild perineal discharge and four had a good outcome with complete resolution of symptoms and satisfactory cosmetic results.

Adult↗
PubMed1993

The incidence and management of catheter occlusion in patients on home parenteral nutrition.

For patients on Home parenteral nutrition (HPN), catheter-related problems are the major source of morbidity and occlusion of the central venous catheter is one of these. We have managed 17 episodes of catheter occlusion in 10 patients on HPN. The median time from insertion to occlusive episode was 23 months. 10 catheters (59%) were saved by the used of thrombolytics (one by thrombolytics and ethanol) and 7 were replaced. The recent incidence of catheter occlusion in this cohort was one episode per 150 patient-months of HPN (0.08 episodes per year). Patients with Crohns disease appear to be at greater risk of developing catheter occlusion (p = <0.05).

Journal Article↗