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Biomedical subjects

A D Fox

Publications and source records attributed to A D Fox.

At least 19 recordsLinked to original sources
PubMed1996

Intraoperative duplex scanning as a means of quality control during carotid endarterectomy.

OBJECTIVES: To identify correctable technical errors following carotid endarterectomy using intraoperative colour duplex sonography (ATL, UM9, HDI). Results were compared with intraoperative flow measurements using an operative flow meter and with middle cerebral artery velocity measured by trans-cranial Doppler (TCD). DESIGN: Prospective study. MATERIALS AND METHODS: 50 consecutive patients undergoing carotid endarterectomy were investigated. Follow-up was performed at 6 weeks using duplex scanning and clinical evaluation. RESULTS: Significant intraoperative technical errors were detected in three patients and were re-explored. Two scans demonstrated kinking or pinching at the distal endarterectomy site requiring patch-plasty and the third revealed a large mass of intramural thrombus. A further 18 endarterectomies yielded 21 additional minor abnormalities. CONCLUSIONS: Duplex sonography provides a sensitive intraoperative technique for detecting thrombus and technical errors. It yields both anatomic and hemodynamic details and is superior to intraoperative flow measurements and transcranial doppler.

Aged↗
PubMed1995

Iso-osmotic bowel preparation improves the accuracy of iliac artery colour flow duplex examination.

Colour flow duplex ultrasonography is currently the non-invasive method of choice for investigating the iliac arteries. However it is only 84-92% sensitive in the best hands when compared with biplanar angiography. Bowel gas and faeces overlying the iliac arteries obscure the vessels and prevent a good ultrasound image. We have previously shown that preparation of the bowel with an iso-osmotic bowel preparation (Klean Prep) improves the clarity of duplex image of the iliac arteries. This is caused by a volume effect which flushes out gas and faeces, leaving a fluid-filled bowel transparent to ultrasound. The aim of this study was to investigate whether this enhanced image increased the diagnostic accuracy of duplex examination. We performed iliac duplex examinations on 56 patients with clinically suspected iliac artery disease, initially with the normal preparation of starving the patients for 12 h and subsequently after preparation by Klean Prep. The results from each investigation were compared with the gold standard of biplanar intra-arterial digital substraction angiography. The use of iso-osmotic bowel preparation (Klean Prep) significantly improved the accuracy of iliac duplex ultrasonography over preparation by 12 h starvation, when compared with biplanar angiography.

Angiography, Digital Subtraction↗
PubMed1995

Do-it-yourself femoropopliteal bypass.

A 74-year-old male claudicant had undergone operative repair of his bilateral varicose veins 22 years earlier. His records confirmed that on the right side he had only had a saphenofemoral disconnection. Duplex scanning and angiography of his right leg demonstrated an occluded superficial femoral artery (SFA) and a network of channels between the proximal SFA stump and the long saphenous vein (LSV). Distal SFA reconstitution occurred through two distal arteriovenous fistulas. We believe that this is the first case of a spontaneous femorodistal bypass graft secondary to neovascularisation recorded in the literature.

Aged↗
PubMed1994

Aortic valvulitis complicating Wegener's granulomatosis.

In a case of Wegener's granulomatosis aortic valve replacement was performed for worsening congestive cardiac failure secondary to aortic incompetence. Two paravalvular lesions and an isolated intraleaflet deficiency of the non-coronary cusp were identified at operation. Histological changes were consistent with a connective tissue disease.

Adult↗
PubMed1992

Reversed vein graft stenosis: early diagnosis and management.

Conscientious surveillance of intrainguinal bypass grafts is mandatory to detect vein graft stenoses, which, if uncorrected, can lead to graft occlusion. It is now widely accepted that noninvasive vascular laboratory studies are the best way to detect these lesions. However, controversy still exists over treatment, specifically whether balloon angioplasty is an acceptable substitute for surgery (patch angioplasty or short jump grafts) in the treatment of these lesions. We have always favored balloon angioplasty as primary treatment and have summarized our experience with treating 72 stenotic reversed femoropopliteal and femorotibial vein grafts, which represent 12% of 521 bypass grafts performed at our institution. Prosthetic and in situ grafts are specifically excluded from this report, as well as occluded grafts, found to have stenotic lesions after lytic therapy. The most common stenotic lesion occurred within 4 cm of the proximal anastomosis (29/72 = 40%). The other sites were near the distal anastomosis (7/72 = 10%), and in the middle of the graft (15/72 = 12%). Eighty-one percent (58/72) of the lesions were treated initially by balloon angioplasty with a 31% recurrence. Twenty-nine percent of the 14 grafts treated surgically by vein patch angioplasty or short jump grafts experienced recurrence. Overall 61% (44/72) of the stenotic grafts were treated by balloon angioplasty alone. The 5-year life-table assisted primary patency after correction of the stenotic lesion was 61%. The patency of the grafts from the time of initial bypass surgery, however, was 80%. Location of the stenosis within the graft was a major determinant of patency. Lesions in the proximal graft, proximal anastomosis, and distal graft taken as a group had significantly better patency than the midgraft and distal anastomotic lesions (5-year patency, 65% vs 48%, p less than 0.001 log rank test). We continue to recommend balloon angioplasty as primary therapy for vein graft stenosis except for those occurring in the midgraft and distal anastomosis. Fortunately, this group accounts for only 36% of lesions seen with reversed veins. Recurrent stenosis after balloon angioplasty should be repaired surgically.

Aged↗
PubMed1991

Thoracoabdominal aneurysm resection after previous infrarenal abdominal aortic aneurysmectomy.

Thoracoabdominal aneurysms in 51 patients were repaired over 5 years ending in February 1991. Fourteen (27%, 14 of 51) patients had a prior infrarenal aneurysm resection (PRA); their data are analyzed separately. The average age of patients who had undergone PRA was 67 years (range: 56 to 86 years). The mean aneurysm diameter was 8.6 cm (range: 5 to 12 cm), and the mean time interval between initial aneurysm surgery and subsequent resection of the thoracoabdominal aneurysm was 8.5 years (range: 2 to 17 years). Three patients in the PRA group were operated on emergently, two because of clinical evidence of rupture; the other patients underwent elective repair. Early mortality (30 days) in the PRA group was significantly related to age (72 years or older versus younger than 72 years: 75% versus 10%, p = 0.04), proximal extent of aneurysm (above diaphragm versus below diaphragm: 50% versus 0%, p = 0.05), ruptured aneurysm (ruptured versus nonruptured: 100% versus 16%, p = 0.06), and a cardiac history of myocardial infarction (57% versus 0%, p = 0.03), congestive heart failure (66% versus 0%, p = 0.01), or arrhythmia (80% versus 0%, p = 0.005). Similar results were seen with the entire group of patients with thoracoabdominal aneurysms except that the proximal extent of the aneurysm was not related to mortality. These results demonstrate that thoracoabdominal aneurysm resection after prior infrarenal aneurysmectomy is not associated with increased mortality or morbidity.

Age Factors↗
PubMed1991

Experimental short-bowel syndrome: effect of an elemental diet supplemented with short-chain triglycerides.

To determine whether short-chain triglycerides (SCTs, 1:1 triacetin:tributyrin, wt:wt) enhance intestinal adaptation in short-bowel syndrome (SBS), male Sprague-Dawley rats underwent 60% distal small-bowel resection with cecectomy and received either a chemically defined diet (CD) or a CD containing 40% of nonprotein energy as either medium-chain triglycerides (MCTs) or SCTs. After 12 d the SCT group had significantly increased jejunal mucosal weight compared with the MCT and CD groups and had significantly increased segment weight and mucosal protein compared with the CD group. In the colon the SCT group had significantly increased segment and mucosal weights and mucosal protein and DNA compared with both the MCT and CD groups. Body-weight change and measurements of serum ketones, albumin, glucose, and triglycerides revealed no significant differences among groups. SCTs improved jejunal and colonic adaptive growth and maintained comparable nutritional status in SBS when compared with CD alone or CD with MCTs.

3-Hydroxybutyric Acid↗
PubMed1988

Dexamethasone administration induces increased glutaminase specific activity in the jejunum and colon.

Exogenous glucocorticoids markedly increase the in vivo uptake and utilization of glutamine by the intestine. Since glutamine is the major oxidative fuel for the small intestine, we investigated whether glucocorticoids induce changes in the specific activity of the enzymes that mediate glutamine degradation (glutaminase) and synthesis (glutamine synthetase). Male Sprague-Dawley rats received a 7-day elemental diet. On Day 5, animals were randomized to one of four groups and received either saline (Control) or one of three doses of dexamethasone im: 0.1 mg/kg (Lodex); 0.3 mg/kg (Middex); or 0.6 mg/kg (Hidex). Forty-eight hours later jejunal and colonic segments were assayed for protein, glutaminase, and glutamine synthetase activity. A stress dose of dexamethasone (Hidex) produced a significant increase in both jejunal and colonic glutaminase specific activity (P less than 0.02 vs Control and P less than 0.05 vs Control, respectively). These data suggest a mechanism whereby glucocorticoids increase the intestinal utilization of glutamine by increasing the specific activity of intestinal glutaminase.

Animals↗
PubMed1988

Inhibition of TPN-associated intestinal mucosal atrophy with monoacetoacetin.

Total parenteral nutrition (TPN) is associated with intestinal mucosal atrophy. Acetoacetate is oxidized in preference to glucose by both enterocytes and colonocytes and is not present in TPN. The purpose of this study was to determine whether replacement of a portion of glucose calories with monoacetoacetin, the glycerol ester of acetoacetate, could inhibit TPN-associated intestinal atrophy. Male Sprague-Dawley rats (200-250 g) underwent superior vena caval cannulation and were assigned to receive chow ad libitium (CHOW), TPN with 0.86 M monoacetoacetin (ACAC), or TPN with 0.86 M glycerol to control for the glycerol component of monoacetoacetin (GLYC). Nitrogen balance was measured over 7 days after which time the animals were weighed and sacrificed. Jejunal and colonic segments were harvested and the mucosal weight, protein, RNA, and DNA contents measured. All groups showed comparable weight gain. Cumulative nitrogen balance was positive for both TPN groups. Significant decreases in mucosal parameters occurred in both TPN groups compared to the CHOW group, but atrophy was significantly inhibited in both jejunum and colon of the ACAC group compared to the GLYC group. Thus, the substitution of monoacetoacetin for glucose calories in parenteral nutrition solutions inhibited TPN-related atrophy of intestinal mucosa while maintaining normal growth.

Acetoacetates↗
PubMedDate not supplied

Effect of a glutamine-supplemented enteral diet on methotrexate-induced enterocolitis.

Administration of an elemental diet to rats given methotrexate (MTX), 20 mg/kg intraperitoneally (ip), results in 100% mortality from severe enterocolitis. Previous studies indicate that glutamine (GLN), which is not present in elemental diets, is the preferred oxidative substrate for the gut and may facilitate intestinal recovery after injury. This study investigated the effects of a glutamine-supplemented elemental diet (GLN-ED) on nutritional status, intestinal morphometry, bacterial translocation and survival in this lethal model of intestinal injury. Three experiments were performed. In the first experiment, rats received an intragastric elemental diet supplemented with either 2% GLN or an equivalent amount of glycine (Control). After 4 days animals received either MTX, 20 mg/kg ip, or saline ip and were killed 3 days later. The GLN-ED resulted in significantly decreased weight loss, improved nitrogen retention, and increased mucosal weight, protein, and DNA content of the jejunum and colon. In the second experiment rats were assigned to diet as in the first experiment, but all animals received MTX. Control diet animals died within 120 hrs of MTX administration. The GLN-ED group had significantly longer survival time and decreased mortality. In the third experiment animals were assigned to diet and MTX as in the first experiment. Ninety-six hrs later aortic blood cultures revealed enteric bacteremia in animals administered MTX. GLN-ED resulted in a significant reduction in the incidence of bacteremia. These experiments showed that a GLN-ED significantly improved nutritional status, decreased intestinal injury, decreased bacterial translocation, and resulted in improved survival in a lethal model of enterocolitis.

Animals↗