Timeliness and outcomes of carotid endarterectomy for symptomatic carotid artery stenosis: a single centre audit.

BACKGROUND: For patients presenting with symptomatic internal carotid artery stenosis, carotid endarterectomy (CEA) surgery is recommended to be performed generally within a 48-hr to 14-day window. This study aimed to assess timeliness of delivery, and outcomes, of CEA surgery in a tertiary vascular centre. METHOD: Patients with symptomatic internal carotid artery stenosis who underwent CEA between 1 June 2014 and 31 June 2017 were identified and data were obtained from hospital records. The timeline of their journey from presentation to surgery was then mapped together with their outcomes. RESULTS: One hundred and seventy-two cases were included in the study. Overall, the median time from development of presenting symptoms to surgery was 9 days and 119 (69%) cases were operated on within 14 days. The median time from development of presenting symptoms to ultrasound imaging was 2 days and the median time from symptoms to vascular referral was also 2 days. There were no deaths, strokes or transient ischaemic attacks within 30 days of CEA. At 1 year, survival was 100% but 15 (8.7%) had experienced at least one transient ischaemic attack or stroke. In the 53 cases operated upon beyond 14 days the dominant cause of delay in 32 (60%) was accessing surgery after review by the vascular service. CONCLUSION: The aim of delivering CEA within 14 days of developing relevant symptoms was achieved in most cases with good outcomes. Nevertheless, points of delay in the patient journey that could be targeted for future quality improvement were identified.

An exploratory study of vibration therapy on muscle function in patients with peripheral artery disease.

OBJECTIVE: The purpose of this exploratory study was to determine whether a single session of vibration therapy (VT) would improve muscular and functional performance in individuals with symptomatic peripheral artery disease (PAD). METHODS: In a randomized, balanced cross-over design fourteen PAD participants with intermittent claudication (mean ± standard deviation; age, 73.9 ± 4.6 years; height, 172.6 ± 68.4 cm; body mass, 85.2 ± 15.7 kg) performed VT and control that involved repeated chair rises, timed up-and-go test, and 6-minute walk test. Each intervention was separated by at least 2 days. Wearable VT devices were positioned on the right and left lower limbs that were turned on during functional testing but were turned off for the control intervention. RESULTS: VT significantly improved (P < .05) repeated chair rises and timed up-and-go test compared with control with a small effect size of 0.46 and 0.45, respectively. Similarly, a significant (P < .01) and meaningful change in 6-minute walk test was noted in VT compared with control. CONCLUSIONS: This exploratory study suggest that VT may enhance functional strength, mobility, and walking performance by extending the onset of claudication and increasing walking distance in PAD with intermittent claudication. However, further study is required to confirm and extend these preliminary findings and determine the potential mechanisms of action in VT.

Development and Validation of a Predictive Model to Aid in the Management of Intact Abdominal Aortic Aneurysms.

OBJECTIVE/BACKGROUND: Predicting outcomes prior to elective abdominal aortic aneurysm repair (AAA) requires critical decision making, as the treatment offered is a prophylactic procedure to prevent death from a ruptured AAA. The aim of this work was to develop and validate a model that may predict outcomes for patients with an AAA and hence aid in clinical decision making. METHODS: A discrete event simulation model was built to simulate the natural history of a patient with an AAA and to predict the 30 day and 2-5 year survival of patients undergoing treatment and surveillance. The input parameters of AAA behavior and impact of comorbidities on survival were derived from the published literature and the New Zealand national life tables. The model was externally validated using a cohort of patients that underwent AAA repair (n = 320) and a cohort of patients undergoing small AAA surveillance (n = 376). All patients had completed at least 5 years of follow up. RESULTS: The model was run three times for each data set to test. This produced a SD < 1%, indicating excellent reproducibility. The observed 30 day mortality for the patients undergoing AAA repair was 9/320 (2.8%) and the expected (model predicted) mortality was 3.8% (c-statistic 0.87 [95 confidence interval 0.75-1.0]). The c-statistic for the predicted 2-5 year survival ranged from 0.68 to 0.71 for the repaired AAA cohort and 0.69 to 0.73 for patients with a small AAA on surveillance. CONCLUSION: The AAA clinical decision tool has the ability to accurately predict the 5 year survival of patients with an AAA. This tool can be used during clinical decision making to better inform clinicians and patients of long-term outcomes. Further validation studies in a wider AAA population are required to test the broader clinical utility of this AAA clinical decision tool.

Survival Disparity Following Abdominal Aortic Aneurysm Repair Highlights Inequality in Ethnic and Socio-economic Status.

OBJECTIVES: Socio-economic status (SES) and ethnicity have been reported as markers influencing the likelihood of increased mortality. The aim of this study was to investigate how SES and ethnicity impacted patient survival after abdominal aortic aneurysm (AAA) repair. METHODS: Consecutive patients undergoing open and endovascular AAA repair during a 14.5 year period were identified. Ethnicity was defined as recorded on health records and SES (a score of 10, where 1 is least deprived and 10 being most deprived) and was linked to census data. Operative outcomes were reported at 30 days and a medium-term survival analysis used the Cox model to report adjusted hazard ratios (HR). RESULTS: A total of 6239 patients with a median age of 75 years and 78.7% males were included. The majority (5,654) were identified as New Zealand (NZ) Europeans, with 421 identified as NZ Maori, 97 identified as belonging to a Pacific ethnic group, and 67 identified as an Asian ethnic group. The median survival follow-up period was 5 years and after adjusting for confounders, those who identified as NZ Maori had the lowest survival compared with all other ethnic groups with a HR of 1.46 (95% CI 1.23-1.72). Living in areas of high social deprivation ≥ 7 was an independent predictor of short and medium-term overall mortality when compared with living in deprivation deciles 1 or 2. CONCLUSIONS: Low SES was identified as a marker of risk for all ethnic groups in relation to both reduced short and medium-term survival. However, regardless of SES, NZ Maori had worse overall medium-term survival following AAA repair than the other ethnic groups. Therefore it appears that both SES and being Maori were markers of increased exposure to risk that negatively impact upon survival after AAA repair. There is a need to ensure systemic processes support initiatives that reduce this inequality.

The impact of CT colonography on abdominal aortic aneurysm referrals in a tertiary hospital.

INTRODUCTION: Computed tomography colonography (CTC) for the detection of colorectal disease is gaining popularity as an alternative to colonoscopy. This has been associated with an increase in incidental extra-colonic findings such as abdominal aortic aneurysms. However, due to the patient selection process of obtaining a CTC, it was hypothesised that this patient cohort might represent a high-risk group. The primary aim of this study was to determine the impact that CTC had on small aneurysm referrals. Owing to the potential selection bias, the secondary aim was to compare baseline characteristics referred by CTC to the cohort referred by other radiological modalities. METHODS: Consecutive patients attending the small aneurysm clinic at a single tertiary centre were included. Baseline patient comorbidities were collected and recorded on a prospective database. The characteristics of patients who had a CTC-detected aneurysm were compared to patients referred by other radiological modalities. RESULTS: There were 566 patients with small aneurysms included. Of these, 96 (17.0%) had their aneurysm detected from CTC and the remaining aneurysms were detected by other radiological modalities. These patients were on average 2 years older and were less likely to have a smoking history. There was no difference in other patient characteristics. CONCLUSION: Computed tomography colonography contributed to the initial diagnosis of one in five patients with small aneurysms. Despite a potential selection bias for patients undergoing CTC, there were no major baseline differences between the CTC cohort and patients referred by other radiological modalities. Routine assessment of the aorta during a CTC may aid in aneurysm detection.

Management of Modifiable Vascular Risk Factors Improves Late Survival following Abdominal Aortic Aneurysm Repair: A Systematic Review and Meta-Analysis.

BACKGROUND: The main determinants of survival following abdominal aortic aneurysm (AAA) repair are preexisting risk factors rather than the method of repair chosen. The main aim of this meta-analysis was to assess the effect of modifiable risk factors on late survival following AAA repair. METHODS: Electronic databases were searched to identify all relevant articles reporting the influence of modifiable risk factors on long-term survival (≥1 year) following elective open aneurysm repair and endovascular aneurysm repair. RESULTS: Twenty-four studies which comprised 53,118 patients, published between 1989 and 2015, were included in the analysis. The use of statin, aspirin, beta-blockers, and a higher hemoglobin level was all significant predictors of improved survival following repair with a hazard ratio (HR) and 95% confidence interval (CI) of 0.75 (0.70-0.80), 0.81 (0.73-0.89), 0.75 (0.61-0.93), and 0.84 (0.74-0.96), respectively. Smoking history and uncorrected coronary disease were associated with a worse long-term survival of HR 1.27 (95% CI 1.07-1.51) and HR 2.59 (95% CI 1.14-5.88), respectively. CONCLUSIONS: Addressing cardiovascular risk factors in patients preoperatively improves long-term survival following AAA repair. Global strategies to improve risk factor modifications in these patients are warranted to optimize long-term outcomes.

Abdominal aortic aneurysm repair in New Zealand: a validation of the Australasian Vascular Audit.

BACKGROUND: In New Zealand (NZ), there are two major sources of operative data for abdominal aortic aneurysm (AAA) repair: the Australasian Vascular Audit (AVA) and the National Minimum Data Set (NMDS). Since the introduction of the AVA in NZ, there has not been any attempt at the validation of outcome data. The aims of this study were to report the outcomes of AAA repair and validate the AAA data captured by AVA using the NMDS. METHODS: AAA procedures performed in NZ from January 2010 to December 2014 were extracted from the AVA and NMDS. Patients identified from the AVA had their survival status matched to the NMDS. Only primary AAA procedures were included for the analysis, with re-interventions and graft infections excluded. Demographical, risk factors and outcome data were used for validation. RESULTS: The number of patients undergoing primary AAA procedure from AVA and NMDS was 1713 and 2078, respectively. The AVA inpatient mortality for elective and rupture AAA was 1.6 and 32.2%, respectively. The NMDS 30-day mortality from AAA was 2.5 and 31.5%. Overall, 1604 patients were available for matching, and the NMDS correctly reported 98.1% of endovascular aneurysm repair and 94.2% of elective AAA repairs; however, there were major differences in comorbidity reporting between the data sets. CONCLUSION: Both data sets were incomplete, but combining administrative (NMDS) and clinical (AVA) data sets provided a more accurate assessment of mortality figures. More than 80% of AAA repairs are captured by AVA, but further work to improve compliance and comorbidity documentation is required.

The costs of elective and emergency abdominal aortic aneurysm repair: a comparative single centre study.

AIM: Population-based screening for abdominal aortic aneurysms (AAA) is being considered in New Zealand. However, there is a lack of data to support its cost effectiveness in this country. The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a single centre in New Zealand. METHODS: A retrospective observational analysis of consecutive patients undergoing elective and emergency AAA repair during the study period (January 2009 to December 2011) was performed. RESULTS: A total of 169 AAA repairs were performed during the study period, of which 114 (67%) were open repairs. Sixty-four of these were open elective AAA repairs, 40 were open ruptured repairs, and 10 were open symptomatic repairs. The mean inpatient cost was $38,804 for open ruptured AAA repair and $28,019 for open elective repair, a difference of $10,785 (95%CI: $249 to $21,321; p=.045). The costs of blood products and laboratory investigations were significantly greater in the ruptured group than the elective. There was no significant difference in length of hospital admission between the groups. CONCLUSIONS: This study demonstrates that ruptured AAA repairs are more expensive than elective AAA repairs, despite no difference in length of hospital stay. The estimated inpatient costs documented in this study for each type of repair can be used for cost-effectiveness analysis in New Zealand. A screening program that reduces the incidence of surgery for ruptured AAA could decrease the average inpatient cost of AAA repairs.

Patient flow to carotid endarterectomy: hastening the patient journey.

BACKGROUND: Early carotid endarterectomy (CEA) after stroke or transient ischaemic attack is the proposed standard of care to prevent recurrent ischaemic events in selected patients. The aim of this study was to investigate if this standard is achieved in a tertiary vascular unit. METHODS: This was a clinical audit. CEAs performed from 1 January 2006 to 31 December 2008 at Christchurch hospital were identified. The value stream from initial presentation to surgery was mapped in two phases (phase 1; 2006-2007 and phase 2; 2008). Patients who had carotid intervention for asymptomatic carotid lesions were excluded. RESULTS: The relevant patient journey was documented in 81 patients (55 phase 1; 26 phase 2). Median time from initial presentation to carotid ultrasound was 5 days in phase 1 and 6 days in phase 2. Time from presentation to vascular surgery review was 22 days in phase 1 and 13 days in phase 2. Time from presentation to CEA significantly reduced from 83 to 32 days between phases (P < 0.005). CONCLUSIONS: There has been a significant decrease in time from presentation to operation between phase 1 and 2. The most significant change is reduced delay between vascular surgery review and CEA. There has been no improvement in urgency of referral for imaging or surgical review. This part of the patient journey is a target for improvement.

Delays in discharge of vascular surgical patients: a prospective audit.

AIM: To quantify delays in discharge for vascular surgical patients and identify causes of such delays. METHODS: A prospective audit of delays in discharge of vascular surgical admissions over a 6-month period was performed. Expected date and time of discharge was compared with actual date and time of discharge. Day-case patients, patients who died during admission and patients not under the direct care of the vascular team were excluded. RESULTS: There were 99 elective and 51 acute admissions accounting for 729 hospital bed days. The median (range) age was 72 years (21-92) and 94% of patients were living independently in the community. Forty-seven percent of patients were discharged on the planned day and time, 21% on the planned day but at a later-than-predicted time and 32% were delayed by more than 1 day. Delays identified in this audit accounted for 135 bed days. Fifteen percent of delays were due to causes that can be improved by internal organization (e.g. delayed paperwork). The majority of the delays (85%) were due to external factors such as lack of rehabilitation beds or lack of placement facilities in nursing homes. Elderly patients and acute admissions were more likely to have long delays in discharge. CONCLUSION: Delays in discharge of vascular surgical patients use a lot of acute surgical bed days. Strategies to prevent delays in discharge should include not only improving internal organization and early identification and referral of patients who require rehabilitation/placement but also increased funding for such essential non-acute services.

First and subsequent nonmelanoma skin cancers: incidence and predictors in a population of New Zealand renal transplant recipients.

BACKGROUND: Renal transplant recipients (RTRs) have an increased risk of developing nonmelanoma skin cancers (NMSCs). The aims of this study were to determine the incidence and subsequent history of NMSCs in RTRs, together with risk factors. METHODS: All patients transplanted between July 1972 and March 2007, and followed up at Christchurch Hospital, New Zealand, were studied. Immunosuppression regimens were mostly prednisone, azathioprine, cyclosporine and prednisone, mycophenolate mofetil, cyclosporine since 1998. RESULTS: Of 384 RTRs, 96 developed at least one NMSC. The median time to first NMSC was 18.3 years (95% CI 14.2, 22.9) from transplant, as estimated by survival analysis. Individual predictors of first NMSC in RTRs were older age at first transplant (P < 0.0001), male sex (P = 0.006) and initial immunosuppression regimen (P = 0.001); only age (P < 0.0001) and male gender (P = 0.003) were significant predictors in a joint model. The mean rate of subsequent NMSCs was 1.67 per year (95% CI = 1.32, 2.11). Older age at first renal transplant (P = 0.009) or at discovery of the first NMSC (P = 0.01) was associated with a higher annual rate of new NMSC following the discovery of the first NMSC. The median survival time to a second NMSC was 2.2 years (CI 1.4, 3.0). Fourteen patients died of metastatic squamous cell carcinoma (15% case fatality). CONCLUSIONS: NMSCs are a major health issue for RTRs, especially in older males. Once RTRs have developed their first NMSC, ongoing surveillance and prompt treatment are essential.

Quality of clinical notes for vascular surgery admissions: a CRABEL score review.

AIM: To compare the quality of patient notes between acute and elective admissions in vascular surgery. METHOD: Patient notes from the 50 most recent acute and elective admissions on a vascular surgical unit were reviewed using the CRABEL score. Points for quality of record keeping were awarded in four categories: Initial Clerking, Subsequent Entries, Consent and Discharge Summary. Total scores were calculated as a percentage. One hundred per cent represents the minimum quality standard expected. Overall CRABEL scores were compared for differences in the quality of note keeping between acute and elective admissions. Further analysis identified areas that need improvement. RESULTS: The mean CRABEL score for acute admissions was 79.2% (77.0-81.3, 95% C.I.) compared to 81.3% (78.8-83.8, 95% C.I.) for elective admissions (t-test P= n.s.). When the individual categories were analysed no statistically significant difference was observed between the two groups for 'Subsequent Entries' and 'Consent' sections (t-test p= n.s.). 'Initial Clerking' category scored significantly better for elective 16.3 out of 20 (15.7-16.9, 95% C.I.) admissions compared to acute admissions 14.6 out of 20 (13.9-15.3, 95% C.I.), (t-test P= 0.00063). 'Discharge Summary' section also scored significantly better for elective admissions 9.9 out of 10 (9.9-10.0, 95% C.I.) compared to acute admissions 9.6 out of 10 (9.3-9.9, 95% C.I.), (t-test P= 0.040). CONCLUSION: There was no statistically significant difference in the overall quality of written patient notes between acute and elective admissions, however 'Initial Clerking' and 'Discharge Summary' were better documented for elective admissions. Both acute and elective admissions were observed to have substandard quality of record keeping.

Macrophage mediated protein hydroperoxide formation and lipid oxidation in low density lipoprotein are inhibited by the inflammation marker 7,8-dihydroneopterin.

The formation of oxidised low density lipoprotein (LDL) within the atherosclerotic plaque appears to be a factor in the development of advanced atherosclerotic plaques. LDL oxidation is dependent on the balance of oxidants and antioxidants within the intima. In addition to producing various oxidants, human macrophages release 7,8-dihydroneopterin which in vivo is oxidised to the inflammation marker neopterin. Using macrophage-like THP-1 cells and human monocyte-derived macrophages, we demonstrate that 7,8-dihydroneopterin is a potent inhibitor of cell-mediated LDL oxidation. 7,8-Dihydroneopterin scavenges the chain propagating lipid peroxyl radical, inhibiting both lipid and protein hydroperoxide formation. A significant amount of the hydroperoxide formed during cell-mediated LDL oxidation was protein hydroperoxide. 7,8-Dihydroneopterin oxidation to 7,8-dihydroxanthopterin was only observed in the presence of both cells and LDL, showing that 7,8-dihydroneopterin had no effect on initiating oxidant generation by the cells. 7,8-Dihydroneopterin did not regenerate alpha-tocopherol but competed with it for the lipid peroxyl radical. Although stimulation of both cell types with gamma-interferon failed to produce sufficient 7,8-dihydroneopterin to inhibit LDL oxidation in tissue culture, analysis of advanced atherosclerotic plaque removed from patients showed that total neopterin levels could reach low micromolar concentrations. This suggests that 7,8-dihydroneopterin synthesis by macrophages could play a significant role in the development of atherosclerotic plaques.

Treatment delays for patients exiting an aortic aneurysm surveillance programme.

BACKGROUND: We have previously reported abdominal aortic aneurysm (AAA)-related mortality in patients who have completed surveillance. This study investigates the journey time of patients who exited the AAA surveillance programme at Christchurch Hospital and underwent elective repair to determine the factors contributing to the interval between completing surveillance and undergoing surgical repair. METHODS: A retrospective review of patient notes was carried out for 25 patients who underwent elective repair of their AAA after exiting the surveillance programme between November 2000 and September 2005. RESULTS: The median time interval between exiting the programme and undergoing repair for patients fit for repair was 6 months. During this waiting period, there were two aneurysm-related deaths. Analysis of the patient journeys showed that those with significant comorbidity, that is, patients who required additional investigation by other clinicians (n = 7), had a median time to repair of 35 weeks. This was substantially increased compared with a median time of 22.5 weeks to repair for the rest (n = 18). CONCLUSION: At our institution the median time for completion of surveillance to repair was 6 months. An AAA with a diameter of 55 mm has an expected risk of rupture of 5%, with mortality approaching 90%. In our series, mortality was 4.9% (two patients died while awaiting repair), consistent with expected figures. Factors contributing to this delay of 6 months to repair were identified. Modifications to this journey are suggested to improve the time interval and therefore hopefully reduce the aneurysm-related mortality in this group.

Informed consent for vascular intervention: completing one audit loop.

AIM: To reaudit documentation of the process of informed consent in patients undergoing vascular surgical and vascular radiological procedures. METHOD: A retrospective audit of randomly selected elective vascular radiological and surgical admissions from October 2005-2006 was undertaken to assess the impact of a previous audit on the documentation of the consent process carried out in 2005. Outpatient clinic letters, handwritten entries in the patients' admission notes, and consent forms were scrutinised and data collated on which doctors took consent, when consent was obtained, what details of the consent process were documented, and whether additional information was made available to patients. RESULTS: 99 sets of notes were reviewed (surgical n=50, radiological n=49). For patients undergoing vascular surgery, the consent form was signed by a consultant in 16 (32%) cases compared to 2 (4%) in the previous audit (p=0.013: Chi-squared). Significantly more vascular radiological consent forms were signed by a consultant (43) compared with surgical consent forms (16) (p<0.001; Chi-squared). Documentation that the risks of surgery had been discussed with the patient was present in 31 (62%) surgical notes and in 20 cases such discussions were documented in letters from clinics. For radiological consent documentation, 34 (69.4%) patient notes recorded discussions regarding procedural risk. Twenty-two (44.9%) of the vascular radiological patients had such risks documented in their outpatient notes by a vascular surgeon compared with 1 (2%) (p <0.001; Chi-squared) in the previous audit. Additional written information was given to 7(14%) of the vascular surgical patients which was similar to the previous audit. No additional information was given to patients who underwent vascular radiological procedures. CONCLUSIONS: Significant improvements have been made since the previous audit with more surgical consultants signing the consent forms and increased documentation of the nature of radiological procedures and risks discussed in outpatient clinics. From the current audit, provision of additional written information (patient information sheets) was an area identified for future improvement.

Patient awareness of risk factors for peripheral vascular disease.

Our aim was to document patient awareness of the risk factors that predispose to peripheral vascular disease (PVD) before and after consultation with a vascular specialist. Two cohorts of patients attending vascular outpatient clinics were interviewed before or after consultation with a vascular surgeon. They were interviewed according to an agreed protocol to determine if they knew that they had PVD and if they knew what the risk factors for vascular disease were. They were specifically asked about smoking, diabetes, hypertension, and hypercholesterolemia. Of 102 patients recruited, 52 were interviewed prior to specialist vascular assessment and 50 after such an assessment. Seventy-nine percent of patients knew that they had PVD before assessment and 96% knew that they had PVD after specialist assessment (P = 0.009). Overall, 60% of patients acknowledged that they received advice about vascular risk factors and 33% recalled receiving such advice from their general practitioner. There was a statistically significant improvement in patient awareness of smoking (73-90%, P = 0.028) and diabetes (23-66%, P = 0.001) as vascular risk factors after specialist consultation. There was no improvement with regard to hypertension and hypercholesterolemia. Identifying and modifying risk factors is an essential part of the treatment of patients with PVD. This study demonstrates that patient awareness of vascular risk factors is generally low and further work is required to establish means for vascular surgical units to improve education for patients with PVD.

Exposure to the electrofusion process can increase the immunogenicity of human cells.

The cellular products obtained following electrofusion (EF) of dendritic cells (DC) and tumour cells have shown promise as cancer vaccines. The immunogenicity of these preparations has been attributed to the presence of small numbers of DC-tumour hybrids and the contribution of the non-hybrid tumour cells present has received little attention. In this report, we investigated the effect of the EF process on the immunogenicity of allogeneic human cells, in particular the colorectal cell line, SW620. EF conditions were optimised to yield the maximum number of DC-SW620 hybrids co-expressing tumour associated antigen (TAA) and DC associated antigens. Exposure of SW620 to EF induced significant increases (P < 0.05) in apoptosis and necrosis. Pre-exposure of SW620 to the EF buffer alone [0.3 M glucose, 0.1 mM Ca(CH3COO)2 and 0.5 mM Mg(CH3COO)(2)] resulted in significant increases in TAA uptake by DC during co-culture (P < 0.05). DC phenotype was, however, not altered by exposure to EF treated tumour cells. In co-cultures of PBMC responders with SW620, the levels of IFNgamma release and cytotoxic activity were significantly increased (P < 0.05) by pre-exposure of the SW620 to EF. Pre-exposure of allogeneic non-T cells, the colorectal cell line Lovo and a breast cancer cell line (MCF7) to EF also significantly (P < 0.05) increased the levels of IFNgamma release by responding PBMC. These results demonstrate that the EF process itself can increase the immunogenicity of at least some human cell types independently of hybrid formation. These findings suggest that EF protocols should be evaluated with regard to the possibility that DC-tumour hybrids may not contribute all, or even most, of the immunostimulatory capacity present in preparations of EF treated cells.