PubMed Health⌕ Search

Biomedical subjects

A Irvine

Publications and source records attributed to A Irvine.

At least 19 recordsLinked to original sources
PubMed2002

Incidence and pattern of long saphenous vein duplication and its possible implications for recurrence after varicose vein surgery.

BACKGROUND: The incidence of long saphenous vein (LSV) duplication has not been clearly established. This anomaly could have implications for recurrence after varicose vein surgery. METHODS: Some 103 saphenograms obtained in 85 patients being considered for peripheral arterial bypass surgery were reviewed. Non-ionic contrast medium was injected directly into the vein or its tributaries at the ankle. Duplications of the LSV and their relation to thigh and calf perforator veins were assessed and recorded by two independent observers. RESULTS: There was evidence of duplication of the LSV in 50 (49 per cent) of the 103 saphenograms. Most duplications were present in the thigh (88 per cent) and the most common pattern was a closed loop (54 per cent). Perforator veins were connected to one branch of the duplication in 42 per cent of the legs (20 per cent of all 103 legs); in half the perforator vein was connected to the non-dominant branch of the duplication. Only ten of the 18 patients who had bilateral saphenograms had duplications in both legs, and only one patient had the same pattern of duplication on both sides. CONCLUSION: The incidence of LSV duplications is higher than previously reported.

Adult↗
PubMed1999

Infection of endovascular stents: an uncommon but important complication.

In this review article, four cases of peripheral endovascular stent infection (including a case presented in this issue of the journal) reported in the medical literature are reported. While the actual incidence of endovascular stent infection is probably low, when it occurs it can have serious consequences. This complication may result in the death of a patient, as seen in two of the case reports. The presentation of this complication, the site of stent deployment, the treatment given and the outcome in each of these cases are discussed. Stent infection should be recognized early to avoid the high morbidity and mortality of this complication.

Humans↗
PubMed1999

Infusional 5-fluorouracil can be a pain in the neck: A case for repositioning displaced Hickman lines.

Increasing numbers of patients receive infusional chemotherapy or total parenteral nutrition via Hickman or Grochong lines. Although the insertion of these indwelling catheters is generally performed under radiological guidance and their positions verified by chest radiography, it is still feasible for them to become displaced at a later date. This possibility should be excluded in patients who develop unusual symptoms during the course of their infusional therapy. We review the reported complications associated with Hickman lines, and present a case history demonstrating that interventional radiology has a valuable role in displaced line repositioning, after the exclusion of thrombosis and infection.

Aged↗
PubMed1998

Inhibition of Tat-mediated transactivation and HIV replication with Tat mutant and repressor domain fusion proteins.

Strategies to inhibit the spread of HIV infection consist of a number of specific molecular approaches. Since viral production is dependent upon Tat-mediated transactivation of the HIV promoter through the Tat activating region (TAR), tat antisense RNA, anti-tat ribozymes, TAR decoys and dominant negative Tat mutant proteins have been suggested as therapeutic inhibitors. We produced and tested several Tat mutant proteins, including a newly generated form Tat delta 58, for the ability to inhibit Tat-mediated transactivation and HIV production. In addition, we generated a new Tat fusion mutant between a C-terminus truncated form of Tat (Tat delta 53) and the Drosophila Engrailed (Eng) transcription repressor domain to test the hypothesis that transcriptional repression can be targeted to the HIV promoter. This fusion mutant was also examined for its capacity to block both Tat-mediated transactivation and HIV replication. We show that three mutants Tat delta 53. Tat delta 58 and Tat delta 53/Eng result in a transdominant phenotype inhibiting wild-type Tat-mediated transactivation, and that the inhibiting potential is increased by the presence of the entire basic domain or the fusion of a repressor domain. However, only the transdominant mutants Tat delta 58 and Tat delta 53/Eng significantly inhibit HIV-1 replication after infection of transfected T cell lines. These results demonstrate the potent inhibiting activity of Tat mutants on HIV replication, and suggest a synergistic effect of Tat transdominant mutant fusion with the Drosophila Engrailed transcription repressor domain.

Cell Line↗
PubMed1998

High level inhibition of HIV replication with combination RNA decoys expressed from an HIV-Tat inducible vector.

Intracellular immunization, an antiviral gene therapy approach based on the introduction of DNA into cells to stably express molecules for the inhibition of viral gene expression and replication, has been suggested for inhibition of HIV infection. Since the Tat and Rev proteins play a critical role in HIV regulation, RNA decoys and ribozymes of these sequences have potential as therapeutic molecular inhibitors. In the present study, we have generated several anti-HIV molecules; a tat-ribozyme, RRE, RWZ6 and TAR decoys and combinations of decoys, and tested them for inhibition of HIV-1 replication in vitro. We used T cell specific CD2 gene elements and regulatory the HIV inducible promoter to direct high level expression and a 3' UTR sequence for mRNA stabilization. We show that HIV replication was most strongly inhibited with the combination TAR + RRE decoy when compared with the single decoys or the tat-ribozyme. We also show that the Tat-inducible HIV promoter directs a higher level of steady-state transcription of decoys and inhibitors and that higher levels of expression directly relate to increased levels of inhibition of HIV infection. Furthermore, a stabilization of the 3' end of TAR + RRE inhibitor transcripts using a beta-globin 3' UTR sequence leads to an additional 15-fold increase in steady-state RNA levels. This cassette when used to express the best combination decoy inhibitor TAR + RRE, yields high level HIV inhibition for greater than 3 weeks. Taken together, both optimization for high level expression of molecular inhibitors and use of combinations of inhibitors suggest better therapeutic application in limiting the spread of HIV.

Cell Line↗
PubMed1996

Twelve years experience of vena cava filtration.

Fourteen patients have required vena caval interruption in a period of 12 years at St Thomas' Hospital. Half of these patients had an underlying malignancy. None of these patients have had clinical or lung scan evidence of recurrent emboli. There were no deaths related to filter insertion and no patient died of a pulmonary embolism. Vena caval interruption is a procedure that is rarely necessary but may be valuable in carefully selected patients.

Adolescent↗
PubMed1995

The incidence of corneal abnormalities in the Silicone Study. Silicone Study Report 7.

OBJECTIVE: To determine factors that were prognostic of corneal abnormalities in eyes following surgery for severe proliferative vitreoretinopathy. DESIGN: Subgroup analysis of the Silicone Study. SETTINGS: Community and university-based ophthalmology clinics. MATERIALS: Eyes with attached maculae at the 24-month follow-up examination that did not have a pre-existing corneal abnormality. INTERVENTIONS: Vitrectomy surgery with long-acting gas or silicone oil. OUTCOME MEASURES: Epithelial and/or stromal edema, corneal opacity and/or previous corneal transplant. RESULTS: The incidence of corneal abnormalities at 24 months was 27% and did not differ significantly between treatment groups. Prognostic factors were preoperative aphakia or pseudophakia (P = .003), preoperative iris neovascularization (P = .006), reoperation (P = .001), the absence of a fluid/gas exchange (P = .03), corneal touch by silicone oil (P = .02), and the presence of aqueous cells (P = .009) or aqueous flare (P = .08). In a multivariate analysis, independent prognostic factors were iris neovascularization (relative risk [RR] = 13.1), aphakia or pseudophakia (RR = 3.0), postoperative aqueous flare (RR = 5.4), and reoperations (RR = 3.4). Corneal abnormalities were correlated with poor visual acuity and hypotony (P < .001). CONCLUSIONS: To our knowledge, this is the first study to document that the incidence rates of corneal abnormalities are equivalent between oil and gas. The incidence of corneal abnormalities in gas-filled eyes was higher than expected, and remained high in oil-filled eyes, despite the use of an inferior iridectomy. Successful surgical repair of the retinal detachment with a single operation, and prevention and early management of corneal touch by silicone oil should help to prevent corneal abnormalities. If rubeosis iridis or severe aqueous flare is present, preoperative treatment with intense topical and possibly periocular steroids might reduce inflammation, which might mediate corneal damage.

Adult↗
PubMed1995

Metastatic liposarcoma in the adrenal gland: report of two cases diagnosed by fine-needle aspiration.

Fine-needle aspiration is now well established in the investigation of retroperitoneal masses. Many of these lesions are first detected in the course of radiological surveys of patients with known or suspected malignancy. It can be difficult to diagnose sarcomas on fine-needle aspiration material as many of these tumour do not show cytological features of malignancy. We describe two cases of metastatic liposarcoma confidently diagnosed on the basis of characteristic cytological features seen in material aspirated from metastatic adrenal tumours.

Adrenal Gland Neoplasms↗
PubMed1995

Macular pucker after successful surgery for proliferative vitreoretinopathy. Silicone Study Report 8.

BACKGROUND: The prevalence of postoperative macular pucker and the factors associated with its development after successful surgery for proliferative vitreoretinopathy (PVR) using silicone oil or gas tamponade are unknown. METHODS: The postoperative status of the macula was determined by reviewing the photographs of 336 eyes taken 6 months after randomization. Two hundred eleven eyes with attached maculas were identified and analyzed to determine the prevalence of macular pucker after silicone oil and gas tamponades in eyes without (group 1) and with (group 2) previous vitrectomy surgery. Data obtained at baseline, from the primary study surgery, and from subsequent examinations and repeat surgeries during a follow-up period of 6 months were analyzed for factors associated with postoperative macular pucker. RESULTS: The 6-month-point prevalence rate of postoperative macular pucker was 15% (32 of 211 eyes). Ten of the 32 eyes were new cases of macular pucker. The authors were unable to document a difference in the 6-month-point prevalence of postoperative macular pucker between group 1 and group 2 eyes (13% versus 18%) or between eyes randomized to gas versus silicone oil (19% versus 12%). Postoperative pucker was three times as likely to develop in aphakic/pseudophakic eyes compared with phakic eyes (P = 0.02). Focal contraction posteriorly causing starfolds, and intravitreal contraction involving the vitreous base or vitreous cavity, were significantly less prevalent in eyes with postoperative macular pucker (P < 0.05). Large (> or = 2 disc diameters) retinal breaks (P = 0.04) were associated significantly with postoperative macular pucker (P = 0.04). The authors were unable to document an association between postoperative macular pucker and the type of adhesive modality used or the extent of its application. Postoperative visual acuity was significantly better if the macula was not puckered (P < 0.01). CONCLUSIONS: The occurrence of macular pucker after successful surgery for retinal detachments complicated by severe PVR is not influenced by the choice of intraocular tamponade. Certain preoperative factors may be associated with postoperative macular pucker.

Cohort Studies↗
PubMed1995

Multiple dermatofibromas in a patient with HIV infection.

We report the case of a 26-year-old man with haemophilia B and human immunodeficiency virus infection (HIV) who presented with a short history of multiple dermatofibromas. He also had troublesome psoriasis for which he was receiving acitretin with UVB therapy and had recently discontinued low-dose daily prednisolone for associated arthropathy. Multiple dermatofibromas are rare and have been reported previously in association with autoimmune disease, especially in individuals receiving immunosuppressive therapy. We believe this to be the first report of multiple dermatofibromas in an individual with advanced HIV infection and propose that it may be related to his viral-mediated immunodeficiency, possibly augmented by UVB and systemic corticosteroid therapy.

Acitretin↗
PubMed1994

Comparative efficacy and safety of micronized fenofibrate and simvastatin in patients with primary type IIa or IIb hyperlipidemia.

BACKGROUND: Few studies have been performed to compare fenofibrate, a second-generation fibrate, and simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. This study was aimed to compare the efficacy of both drugs in reducing atherogenic risk factors in type IIa or IIb hyperlipidemia. METHODS: Sixty-three patients entered this single-center, double-blind, crossover trial. Sixty patients (32 with type IIa and 28 with type IIb hyperlipidemia) were randomized to treatment for 3 months with a single daily 200-mg dose of micronized fenofibrate or 20 mg of simvastatin and then changed to the alternative treatment for a further 3-month period. RESULTS: After the first treatment period, in both types IIa and IIb, fenofibrate and simvastatin produced similar significant reductions in levels of total cholesterol and low-density lipoprotein cholesterol; high-density lipoprotein cholesterol levels were increased with both drugs in type IIb. Only fenofibrate decreased total triglyceride levels in type IIb, Lp(a) lipoprotein levels in patients with high baseline values, and fibrinogen. After the second period of treatment, in both types IIa and IIb, switching from fenofibrate to simvastatin resulted in a further reduction in total cholesterol and low-density lipoprotein cholesterol levels. The difference in the response of the two treatments on levels of total triglycerides, Lp(a) lipoprotein, and fibrinogen was confirmed after changing over to the alternative treatment. This short-term study showed few adverse effects for both drugs. CONCLUSIONS: Fenofibrate and simvastatin provide similar variations on total cholesterol and low-density lipoprotein cholesterol levels after a 3-month treatment period, with simvastatin having the capacity to decrease these measures further when administered after fenofibrate. However, fenofibrate exhibits a significant effect on other established risk factors, such as total triglyceride, fibrinogen, and Lp(a) lipoprotein levels, and accordingly has a broader spectrum of activity than simvastatin.

Adolescent↗
PubMed1994

The value of a baseline liver biopsy prior to methotrexate treatment.

Two patients with severe disabling psoriasis were treated with methotrexate (MTX). As a short course of treatment was envisaged, a pretreatment liver biopsy was not performed. Although both patients developed similarly abnormal levels of hepatic enzymes after low cumulative doses of MTX (440 and 450 mg), subsequent liver biopsies revealed contrasting findings. In one patient the histological features were normal. However, in the second, there was hepatic fibrosis, and the absence of a pretreatment biopsy led to problems with interpretation of these histological findings. As a liver biopsy is by far the most reliable method of detecting liver disease, we suggest that it is still of value to include a baseline liver biopsy in the pretreatment assessment of patients even when only a short course of MTX is planned.

Adult↗
PubMed1993

Traumatic damage to the nodal axolemma: an early, secondary injury.

Electronmicroscopical investigations were made in a model of optic nerve damage in guinea-pigs on the development of acute axonal damage on an ultrastructural basis. It was expected to obtain thereby further information on mechanisms underlying axonal damage in traumatic brain injury. For that purpose an injury apparatus was employed to deliver defined elongation and/or tensile strains to the optic nerve. Transmission electronmicrographs were examined of longitudinal and transverse nerve sections throughout its entire length. The most severe abnormalities were identified in the prechiasmatic portion of the nerve. Among others, elongations of the nodes of Ranvier were encountered, swollen axons with accumulation of organelles, and even disrupted axons having a morphology similar to retraction balls. In all instances, abnormal axons were found together with axons having a normal structural appearance. Nodes of Ranvier demonstrated outward dilatations of the nodal axolemma and of the adjacent axoplasm, which are named as nodal blebs. Nodal blebs occurred already 15 min after injury, and were fully developed at 6 or 24 hrs. The blebs had disappeared again after 5-7 days. The axoplasm in the blebs demonstrated considerable disorganization of cytoskeletal elements with an array of amorphous material appearing as granular degeneration. Taken together, the present experimental model is a useful approach to analyse axonal damage at the ultrastructural level as it may occur in white matter of the central nervous system.

Animals↗
PubMed1992

Portal vein thrombosis in a complicated case of Crohn's disease.

Portal vein thrombosis is a rare complication of ulcerative colitis and is invariably fatal. This report describes a patient with severe Crohn's disease who underwent elective surgery complicated by an anastomotic disruption with faecal peritonitis. Following emergency laparotomy he developed left hypochondrial pain which was a manifestation of splenomegaly consequent upon portal vein thrombosis. Anticoagulation was successful in preventing further spread of the thrombosis as monitored by colour Doppler ultrasound. Severe active disease, surgery and sepsis have been recognized as predisposing factors for thromboembolic complications in inflammatory bowel disease and this patient was exposed to all three. It is conceivable that portal vein thromboses occur more commonly than suspected and ultrasound scanning could ascertain the prevalence if performed prospectively.

Adult↗
PubMed1991

Haemodynamic significance of incompetent calf perforating veins.

A total of 149 consecutive unselected patients (221 limbs) who presented with signs and symptoms of chronic venous problems (varicose veins with or without ankle oedema, skin changes and leg ulcers) have been studied by clinical examination, ascending deep to superficial venography, Doppler ultrasound and ambulatory venous pressure measurements. Of the limbs, 180 (82 per cent) had varicose veins without obstruction in the deep veins or reflux in the popliteal or femoral veins while 41 (18 per cent) had deep venous disease. Of the 180 limbs with 'primary' varicose veins 110 (60 per cent) did not have incompetent calf perforating veins (group A) while 70 (40 per cent) did (group B). On the basis of the ambulatory venous pressure after calf muscle exercise and the refilling time, the incompetent calf perforating veins of limbs in group B belonged to three subgroups of different haemodynamic significance. In 20 limbs (30 per cent) they were found to be of no haemodynamic significance, in 25 (35 per cent) of moderate haemodynamic significance and in 25 (35 per cent) of major haemodynamic significance. The last were, on clinical examination, indistinguishable from limbs with deep venous disease although they had patent deep veins with competent popliteal valves.

Humans↗
PubMed1991

Focal axonal injury: the early axonal response to stretch.

The development of a model for axonal injury in the optic nerve of the guinea pig has allowed analysis of early morphological changes within damaged axons. We provide evidence that the initial site of damage after stretch is the nodes of Ranvier, some of which develop 'nodal blebs'. The development of nodel blebs is correlated with the loss of subaxolemmal density, disruption of the neurofilament cytoskeleton and aggregation of membranous profiles of smooth endoplasmic reticulum. Nodal blebs are numerous 15 min after injury but less so at later survivals. The glial-axonal junction is intact at early survivals in damaged nodes. Marked accumulation of membranous organelles occurs in the paranodal and internodal regions adjacent to damaged nodes between two and six hours and is correlated with disruption of the myelin sheath. Axotomy and the formation of degeneration bulbs occurs between 24 and 72 h. The area of axonal injury is invaded by phagocytic cells by 72 h and large numbers of myelin figures occur within the neuropil until 14 days. The results are compared with those of other studies of diffuse axonal injury and other neuropathies. The time course of axonal changes is more rapid than during Wallerian degeneration. Our data from longer surviving animals is exactly comparable with published data. We are confident that the principal site of axonal injury is the node of Ranvier. We suggest that damage at the node results in disruption of axonal transport, which in turn leads to a cascade of events, culminating in axotomy between 24 and 72 h after the initial insult.

Animals↗