Addressing bioterrorism concerns: options for investigating the mechanism of action of Staphylococcus aureus enterotoxin B.

Staphylococcal enterotoxin B (SEB) is of concern to military and civilian populations as a bioterrorism threat agent. It is a highly potent toxin produced by Staphylococcus aureus and is stable in storage and under aerosolisation; it is able to produce prolonged highly incapacitating illness at very low-inhaled doses and death at elevated doses. Concerns regarding SEB are compounded by the lack of effective medical countermeasures for mass treatment of affected populations. This article considers the mechanism of action of SEB, the availability of appropriate experimental models for evaluating the efficacy of candidate medical countermeasures with particular reference to the need to realistically model SEB responses in man and the availability of candidate countermeasures (with an emphasis on commercial off-the-shelf options). The proposed in vitro approaches would be in keeping with Dstl's commitment to reduction, refinement and replacement of animal models in biomedical research, particularly in relation to identifying valid alternatives to the use of nonhuman primates in experimental studies.

The value of vein graft surveillance in bypasses performed with small-diameter vein grafts.

We assessed the impact of preoperative diameter of the venous conduit on reintervention rate and outcome following infrainguinal vein graft bypass. Consecutive infrainguinal vein bypasses between January 2001 and December 2006 were reviewed. All patients underwent preoperative measurement of vein graft diameter (VGD). Grafts were classified into those with VGD <3.5 mm and those with VGD > or =3.5 mm. All patients were enrolled in a duplex surveillance program. The association between VGD and reintervention rate was assessed. Graft patency and amputation rates were compared. There were 377 bypasses followed up for a median of 23 months (range 8-67). VGD was <3.5 mm in 139 grafts (36.9%) and > or =3.5 mm in 238 grafts (63.1%). A higher proportion of smaller vein grafts (32.3%) required reintervention to maintain graft patency compared with larger conduits (20.2%) (chi(2) = 7.7, p < 0.001). VGD (odds ratio [OR] = 2.87, 95% confidence interval [CI] 1.63-3.81; p < 0.001), smoking (OR = 1.83, 95% CI 1.39-3.20; p = 0.02), and type of bypass (OR = 1.86, 95% CI 1.49-2.47; p = 0.02) were variables associated with higher reintervention rate. There was no difference in graft patency (p = 0.13) or amputation rates (p = 0.35) between the two groups. Use of smaller vein grafts was associated with a higher reintervention rate. Provided that these grafts are surveyed and where necessary repaired, the use of smaller vein grafts is successful and expands the availability of autogenous conduit for infrainguinal arterial reconstruction.

Balloon angioplasty as the primary treatment for failing infra-inguinal vein grafts.

BACKGROUND: We sought to evaluate the role of balloon angioplasty as the primary modality in the management of vein graft stenoses. METHODS: Patients who underwent infrainguinal vein graft bypass from January 2002 to December 2007 were enrolled into a surveillance program. Grafts which developed critical stenoses were identified and underwent urgent angiography with a view to angioplasty of the stenotic lesion. Lesions which were deemed unsuitable for angioplasty underwent urgent surgical repair. RESULTS: Four hundred and eleven grafts were followed up for a median of 19 months (range: 2-61). Ninety-six grafts (22.6%) developed critical stenosis. Twelve grafts occluded prior to repair and one was not intervened upon electively. Eight grafts underwent primary surgical repair. Seventy-six grafts underwent 99 endovascular procedures. Technical success was achieved in 60 grafts (78.9%). Of the grafts in which technical success had not been achieved, eight underwent repeat angioplasty and three were surgically repaired. Twenty-four grafts underwent repeat angioplasty for re-stenosis with a technical success rate of 71%. No difference was observed in graft patency (P=0.08) or amputation rates (P=0.32) between the grafts requiring intervention to maintain patency, and grafts which did not. Smoking [OR: 2.61 (95% CI: 1.51-4.53), (P=0.006)], diabetes [OR: 2.55 (95% CI: 1.49-4.35), (P=0.006)], renal failure [OR: 1.89 (95% CI: 1.19-3.38), (P=0.040)] and recurrent stenosis [OR: 3.22 (95% CI: 1.63-4.69), (P<0.001)] were risk factors for graft occlusion. CONCLUSIONS: Balloon angioplasty of failing infrainguinal vein bypass grafts is safe and can be performed with an acceptable medium term patency rate, albeit with a significant risk of re-stenosis which can be successfully treated in most patients using repeat endovascular intervention.

Outcome from abdominal aortic aneurysms in Scotland, 1991-2006.

BACKGROUND: This study assessed the impact of sex, presentation and treatment on outcome from abdominal aortic aneurysm (AAA) in Scotland. METHODS: All patients admitted from January 1991 to December 2006 with a primary diagnosis of AAA were identified. Patients were stratified by age, sex, admission diagnosis (ruptured versus intact) and procedure performed (endovascular versus open repair). Multivariable logistic regression analysis was used to determine predictors of mortality. RESULTS: Some 9779 men and 2927 women were admitted with a principal diagnosis of AAA. Women were significantly older than men (median (range) age 75 (35-97) versus 71 (17-96) years; P < 0.001). A higher proportion of women presented with a ruptured AAA (29.5 versus 27.5 per cent; P = 0.043). Age (odds ratio (OR) 2.52 (95 per cent confidence interval 2.36 to 2.74); P < 0.001), female sex (OR 1.63 (1.48 to 1.78); P < 0.001) and admission diagnosis (OR 10.49 (9.53 to 11.54); P < 0.001) were independent predictors of early death, whereas endovascular repair predicted survival (OR 0.67 (0.58 to 0.76); P < 0.001). CONCLUSION: Women presenting with an AAA were older and more likely to be admitted with a ruptured aneurysm. Female sex was an independent risk factor for death from AAA.

Endovascular treatment of common iliac occlusion in the presence of persistent sciatic artery.

Persistent sciatic artery is a rare congenital anomaly. It is associated with increased incidence of aneurysmal dilatation, thrombosis, distal embolization, and atherosclerotic change. We describe the case of a patient with persistent sciatic artery who presented with a critically ischemic left leg as a result of an occluded left common iliac artery, which was treated by angioplasty and stenting, and discuss the endovascular iliac recanalization in the presence of a persistent sciatic artery.

Beware of varicose veins in a patient with sturge-weber syndrome.

This report describes the case of a 21-year-old man with a history of Sturge-Weber syndrome and varicose veins. Examination of the left lower limb revealed the presence of significant port-wine staining, and hypertrophy. Duplex examination revealed a severely hypoplastic deep venous system with a tortuous, dilated, long saphenous vein, which was competent and responsible for a significant proportion of venous return from the left lower limb, thus confirming the diagnosis of Klippel-Trenaunay syndrome. The patient was counseled regarding the implications of the diagnosis and was treated conservatively. The association between these two rare syndromes has been previously reported in the nonvascular literature. We believe that features of the Sturge-Weber syndrome or other forms of mesodermal phakomatosis should alert a clinician to the presence of lower limb venous malformations, which will need to be investigated prior to embarking on what could be potentially detrimental venous surgery.

Endovascular repair of a ruptured mycotic aneurysm of the common iliac artery.

This report describes the case of a ruptured mycotic aneurysm of the left common iliac artery, successfully treated with endovascular stent-grafting. A 64-year-old woman underwent diagnostic coronary angiography complicated by an infected hematoma of the left groin. Seven days later, she developed methicillin-resistant Staphylococcus aureus septicemia and CT scan evidence of perivascular inflammation around the left common iliac artery. This was followed by rupture of a mycotic aneurysm of the left common iliac artery. The lesion was successfully treated with a stent-graft and prolonged antibiotic therapy, and the patient remains free of infection 10 months later. Accumulating evidence suggests that endovascular repair can be used safely for the repair of ruptured infected aneurysms.

Multiple vaccine and pyridostigmine interactions: effects on EEG and sleep in the common marmoset.

Following active service during the 1990/1991 Gulf conflict, a number of UK and US veterans presented with a diverse range of symptoms, collectively known as Gulf Veterans' Illnesses (GVI). The administration of vaccines and/or the pretreatment against possible nerve agent poisoning, pyridostigmine bromide (PB), given to Armed Forces personnel during the Gulf conflict has been implicated as a possible factor in the aetiology of these illnesses. The possibility that long-term health effects may result from the administration of these vaccines (anthrax, pertussis, plague, yellow fever, polio, typhoid, tetanus, hepatitis B, meningococcal meningitis and cholera) and/or PB, have been investigated using a non-human primate model, the common marmoset. This paper reports the results from two aspects of the study, brain electrical activity (EEG, collected during performance of a touchscreen mediated discrimination task) and sleep. There were no marked long-term changes in EEG or sleep patterns that could be attributed to vaccines and/or PB administration. The changes that were detected were predominantly time related and independent of treatment. Where statistical differences were detected between treatments, the magnitudes of the difference were relatively minor and therefore not regarded as having long term biological significance.

Multiple vaccine and pyridostigmine interactions: effects on cognition, muscle function and health outcomes in marmosets.

Following active service during the 1990/1991 Gulf Conflict, a number of UK and US veterans presented with a diverse range of symptoms, collectively known as Gulf Veterans Illnesses (GVI). The administration of vaccines and/or the pretreatment against possible nerve agent poisoning, pyridostigmine bromide (PB), given to armed forces personnel during the Gulf Conflict has been implicated as a possible factor in the aetiology of these illnesses. The possibility that long-term health effects may result from the administration of these vaccines (anthrax, pertussis, plague, yellow fever, polio, typhoid, tetanus, hepatitis B, meningococcal meningitis and cholera) and/or PB, have been investigated using a non-human primate model, the common marmoset. This paper reports the results from three aspects of the study, cognitive behaviour (performance of a touchscreen mediated discrimination task), muscle function (performance of a simple strength test) and general health. There were no marked long-term changes in cognition, muscle function or health that could be attributed to vaccines and/or PB administration. Statistical differences related to treatments were only observed in two aspects of cognition and one of clinical chemistry. These changes were transient in nature and their magnitude were minor and, in consequence, was not regarded as having long-term biological significance.

Preliminary results from the use of the novel Interactive binocular treatment (I-BiT) system, in the treatment of strabismic and anisometropic amblyopia.

BACKGROUND: We have developed a novel application of adapted virtual reality (VR) technology, for the binocular treatment of amblyopia. We describe the use of the system in six children. METHODS: Subjects consisted of three conventional treatment 'failures' and three conventional treatment 'refusers', with a mean age of 6.25 years (5.42-7.75 years). Treatment consisted of watching video clips and playing interactive games with specifically designed software to allow streamed binocular image presentation. RESULTS: Initial vision in the amblyopic eye ranged from 6/12 to 6/120 and post-treatment 6/7.5 to 6/24-1. Total treatment time was a mean of 4.4 h. Five out of six children have shown an improvement in their vision (average increase of 10 letters), including those who had previously failed to comply with conventional occlusion. CONCLUSIONS: Improvements in vision were demonstrable within a short period of time, in some children after 1 h of treatment. This system is an exciting and promising application of VR technology as a new treatment for amblyopia.

Modified virtual reality technology for treatment of amblyopia.

PURPOSE: The conventional patching/occlusion treatment for amblyopia sometimes gives disappointing results for a number of reasons: it is unpopular, prolonged, frequently resulting in poor or noncompliance, and also disrupts fusion. The aim of this research was to develop a novel virtual-reality (VR)-based display system that facilitates the treatment of amblyopia with both eyes stimulated simultaneously. METHODS: We have adopted a multidisciplinary approach, combining VR expertise with a team of ophthalmologists and orthoptists to develop the Interactive Binocular Treatment (I-BiT) system. This system incorporates adapted VR technology and specially written software providing interactive 2D and 3D games and videos to the patient via a stereo (binocular) display, and a control screen for the clinician. RESULTS: We developed a prototype research system designed for treatment of amblyopia in children. CONCLUSIONS: The result is a novel way to treat amblyopia, which allows binocular treatment. It is interactive, and as it is partially software based, can be adapted to suit the age/ability, and needs of the patient. This means that the treatment can be made captivating and enjoyable. Further research is on-going to determine the efficacy of this new modality in the treatment of amblyopia.

Cutting-balloon-associated vascular rupture after failed standard balloon angioplasty.

The following case reports illustrate a possible complication of vascular rupture when cutting balloon dilatation is performed immediately after failed standard balloon angioplasty to the same diameter. Deferral of the cutting balloon dilatation should be considered in such circumstances.

A simple method for assessing muscle function in common marmosets.

A novel method of assessing muscle function in the common marmoset was developed as part of a multidisciplinary long-term study. The method involved home cage presentation of a weight-pulling task. Over a 4-5 month period, 38 of 42 animals were successfully trained to displace weights of up to 920 g (mean 612+/-20 g). Performance, following initial training, was stable and independent of gender or body weight.

Randomized clinical trial of distal anastomotic interposition vein cuff in infrainguinal polytetrafluoroethylene bypass grafting.

BACKGROUND: The aim was to examine the effect of a Miller vein cuff at the distal anastomosis on the medium- to long-term patency and limb salvage rates of femoral to above-knee and femoral to below-knee popliteal artery polytetrafluoroethylene (PTFE) bypasses. METHODS: This study involved extended follow-up of the original cohort of patients included in a previously reported multicentre randomized clinical study. Outcome measures were bypass graft patency and limb salvage. RESULTS: Two hundred and sixty-one bypass operations were originally randomized. For this study, full data were available on 235 (120 with a Miller cuff, 115 without). The cumulative 5-year patency rate for above-knee bypasses with a Miller cuff was 40 per cent, compared with 42 per cent for non-cuffed bypasses (P = 0.702). The cumulative 3-year patency rate for below-knee bypasses with a Miller cuff was 45 per cent, compared with 19 per cent for non-cuffed bypasses (P = 0.018). A Miller cuff had no significant effect on limb salvage for above-knee or below-knee bypasses. CONCLUSION: Three-year patency rates of femoral to below-knee popliteal PTFE bypasses were improved by a Miller cuff. Miller cuffs had no effect on patency rates for femoral to above-knee popliteal bypasses at 5 years and did not improve limb salvage in either group.

Growth factors in the treatment of diabetic foot ulcers.

BACKGROUND: Chronic foot ulceration is a major source of morbidity in diabetic patients. Despite traditional comprehensive wound management, including vascular reconstruction, there remains a cohort of patients with non-responding wounds, often resulting in amputation. These wounds may benefit from molecular manipulation of growth factors to enhance the microcirculation. METHODS: A review of the current literature was performed using Pubmed, with secondary references obtained from key articles. RESULTS AND CONCLUSION: There has been a generally disappointing clinical outcome from growth factor trials, although topical platelet-derived growth factor has shown significant benefit and should be considered in non-healing, well perfused ulcers after failure of conventional wound care. The modulatory role of the extracellular matrix in the cellular response to growth factors and data from regenerative-type fetal wound healing are further areas of interest. The chemical induction of microvessel formation may become a future therapeutic option.

An extensive monoclonal antibody panel for the phenotyping of leukocyte subsets in the common marmoset and the cotton-top tamarin.

New World monkeys are valuable animal models to study human diseases. To determine the phenotype of cells involved in immune responses, we used flow cytometry to screen a large panel of anti-human monoclonal antibodies (mAb) for cross-reactivity with cells of the common marmoset and the cotton-top tamarin. Certain antigens (e.g., CD2, CD8, CD20) are well conserved. However, CD10, CD23, and CD33 showed a clear discrepancy in their reaction patterns in both species, indicating that significant differences on the epitope level occurred during evolution. Epstein-Barr virus-transformed B-cell lines were shown to be a valuable tool for screening B-cell-specific reagents. In some cases, fluorescein isothiocyanate (FITC) and phycoerythrin (PE) modification of mAbs had a negative effect on the binding capacity, which stressed the importance of choosing the right label. Despite the fact that some CD antigens were not detected, adequate numbers of cross-reactive mAbs were identified to perform extensive studies on immunological functions in both the common marmoset and the cotton-top tamarin.

Variability in measurement of internal carotid artery stenosis by arch angiography and duplex ultrasonography--time for a reappraisal?

OBJECTIVES: to determine the inter- and intra-observer variability of ICA stenosis measurement using duplex, ECST and NASCET methods. DESIGN: a retrospective review of arch angiograms and carotid duplex scans in 50 patients. MATERIALS AND METHODS: carotid stenoses were calculated by three independent observers according to NASCET and ECST methods. Variation between observers for NASCET and ECST was determined. For each observer, the variation between NASCET and ECST was determined. The variation between duplex and both NASCET and ECST was determined. RESULTS: inter-observer agreement on the degree of ICA stenosis was clinically and statistically good for NASCET but was poorer for ECST. For each observer, comparison between NASCET and ECST showed 95% limits of agreement of around 50 percentage points. Comparison of duplex with NASCET and ECST showed similar 95% limits of agreement. CONCLUSIONS: arch angiography allows reproducible measurement of carotid stenosis by the NASCET method between different observers. For the ECST method, reproducibility is not so good. Variations in results between NASCET and ECST and between angiography and duplex are significant. In view of the similar results of the NASCET and ECST trials, this suggests that degree of stenosis may only be a surrogate marker for outcome following carotid endarterectomy.

Biological consequences of multiple vaccine and pyridostigmine pretreatment in the guinea pig.

An investigation of the possible interactions between combinations of vaccines and pyridostigmine bromide (PB) has been undertaken in the guinea pig. This study is part of a research programme funded by the UK Government to determine any effects of the pretreatment regimes given to UK Forces during the Persian Gulf conflict of 1990-1991. The study was designed to simulate PB administration and to model multiple vaccination protocols that were experienced by UK Forces, modelling a "worst case" situation in which all ten vaccines and PB were administered within a short period of time. Seven of the vaccines were health and hygiene (H+H) vaccines given to protect against endemic diseases and two vaccines to protect against the biological warfare agents anthrax and plague. In addition, pertussis vaccine was administered as an adjuvant to reduce the time to achieve immunity against anthrax. Four groups of eight animals were treated with 1/20th, 1/10th or 1/5th human doses of vaccines or vehicles, respectively. The PB or saline was delivered by implanted 28 day mini-osmotic pumps to achieve a mean red blood cell acetylcholinesterase (AChE) inhibition of around 30%. Body weight, temperature, immunological response, biochemical indices and spontaneous activity were monitored for 72 days. Although immunological responses to bacterial vaccines were observed, there were no remarkable findings in the parameters measured other than minor changes in body weight (4.9% decrease at the 1/5th human dose of vaccines) and temperature increases in response to vaccination. Animals in all groups remained generally healthy and active without visible adverse signs throughout the study. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

Characterization of ricin heterogeneity by electrospray mass spectrometry, capillary electrophoresis, and resonant mirror.

Electrospray mass spectrometry (ES/MS), capillary-zone electrophoresis (CZE), capillary isoelectric focusing (CIEF), and multianalyte resonant mirror are used to evaluate the heterogeneity of samples of ricin toxins extracted from five horticultural varieties of Ricinus communis seeds: R. communis zanzibariensis, carmencita, impala, sanguineus, and gibsonii. The investigation is also extended to the geographical provenance of the beans. Combining mass spectrometry, CE techniques, and resonant mirror results in a powerful analytical tool capable to characterize and differentiate between different varieties of ricin toxins. Each technique complements the others, adding another level of information. This study reveals a large extent of heterogeneity for each cultivar, demonstrating that ricin toxins consist of a series of glycosylated proteins most likely originating from a multigene family. By combining these techniques, it is possible to differentiate between zanzibariensis and the other four varieties, and that variations in the functional characteristics may be observed between the different cultivars. This study demonstrates that knowledge of the variety of R. communis beans used and their geographical provenance is essential before any type of investigation of ricin toxins is carried out. Consequently, any unusual behavior observed can only be attributed to that particular cultivar studied and not automatically extended to include all R. communis varieties.