Use of Multiple Irradiations and Reference Materials as Comparators in Quality Control of Neutron Activation Analysis Data of Biological Samples.

We propose that several different reactor irradiation times followed by assaying of activity for differential counting periods may be employed for quality control (QC) of neutron activation analysis (NAA) data of biological samples. It is also recommended that three to four reference materials (RMs) of similar matrix but from different agencies such as National Institute of Standards and Technology (NIST, USA), International Atomic Energy Agency (IAEA, Vienna), Institute of Nuclear Chemistry and Technology (INCT, Poland), and National Institute of Environmental Studies (NIES, Japan) including a synthetic multielemental primary standard should always be analyzed simultaneously along with the samples. Finally, the mean ± σ values so obtained may be considered as more reliable after statistical analysis. Our analytical data for Na and K in three RMs (SRM 1572, CRM H-9, and Bowen's Kale) using different irradiation periods of 15 m, 2 h, 6 h, and 1 day were comparable with the certified values within error range of + 0.2 to - 2.7%. We report our data for 20 elements in two candidate RMs corn flour (INCT-CF-3) and soya bean flour (INCT-SBF-4) from the INCT, Poland, where Z-score values for most elements are in reasonable range of certified values.

Imaging of atherosclerosis.

It is now well recognized that the atherosclerotic plaques responsible for thrombus formation are not necessarily those that impinge most on the lumen of the vessel. Nevertheless, clinical investigations for atherosclerosis still focus on quantifying the degree of stenosis caused by plaques. Many of the features associated with a high-risk plaque, including a thin fibrous cap, large necrotic core, macrophage infiltration, neovascularization, and intraplaque hemorrhage, can now be probed by novel imaging techniques. Each technique has its own strengths and drawbacks. In this article, we review the various imaging modalities used for the evaluation and quantification of atherosclerosis.

Multiple inflow pulsed arterial spin-labeling reveals delays in the arterial arrival time in minor stroke and transient ischemic attack.

Our purpose was to use multiple inflow pulsed ASL to investigate whether hemodynamic AAT information is sensitive to hemispheric asymmetry in acute ischemia. The cohorts included 15 patients with acute minor stroke or TIA and 15 age-matched controls. Patients were scanned by using a stroke MR imaging protocol at a median time of 74 hours. DWI lesion volumes were small and functional impairment was low; however, perfusion abnormalities were evident. Prolonged AAT values were more likely to reside in the affected hemisphere (significant when compared with controls, P < .048). An advantage of this ASL technique is the ability to use AAT information in addition to CBF to characterize ischemia.

Magnetic resonance imaging contrast agent targeted toward activated platelets allows in vivo detection of thrombosis and monitoring of thrombolysis.

BACKGROUND: Platelets are the key to thrombus formation and play a role in the development of atherosclerosis. Noninvasive imaging of activated platelets would be of great clinical interest. Here, we evaluate the ability of a magnetic resonance imaging (MRI) contrast agent consisting of microparticles of iron oxide (MPIOs) and a single-chain antibody targeting ligand-induced binding sites (LIBS) on activated glycoprotein IIb/IIIa to image carotid artery thrombi and atherosclerotic plaques. METHODS AND RESULTS: Anti-LIBS antibody or control antibody was conjugated to 1-microm MPIOs (LIBS MPIO/control MPIO). Nonocclusive mural thrombi were induced in mice with 6% ferric chloride. MRI (at 9.4 T) was performed once before and repeatedly in 12-minute-long sequences after LIBS MPIO/control MPIO injection. After 36 minutes, a significant signal void, corresponding to MPIO accumulation, was observed with LIBS MPIOs but not control MPIOs (P<0.05). After thrombolysis, in LIBS MPIO-injected mice, the signal void subsided, indicating successful thrombolysis. On histology, the MPIO content of the thrombus, as well as thrombus size, correlated significantly with LIBS MPIO-induced signal void (both P<0.01). After ex vivo incubation of symptomatic human carotid plaques, MRI and histology confirmed binding to areas of platelet adhesion/aggregation for LIBS MPIOs but not for control MPIOs. CONCLUSIONS: LIBS MPIOs allow in vivo MRI of activated platelets with excellent contrast properties and monitoring of thrombolytic therapy. Furthermore, activated platelets were detected on the surface of symptomatic human carotid plaques by ex vivo MRI. This approach represents a novel noninvasive technique allowing the detection and quantification of platelet-containing thrombi.

Filter no reflow during percutaneous coronary interventions using the Filterwire distal protection device.

BACKGROUND: Distal protection devices are increasingly used to prevent embolization during percutaneous coronary interventions (PCI) in saphenous vein grafts (SVG) and native coronary arteries (NV). During interventions with the Filterwire device we have observed reduced flow that is reversible following removal of the filter (filter no reflow, FNR), which might be erroneously interpreted as true no reflow and might be associated with reduced capture efficiency of the basket. METHODS: We analyzed the incidence of FNR in 58 patients (60 lesions) at high risk of embolization undergoing PCI of either a SVG or a NV using the Filterwire (Boston Scientific, Natick, MA). Qualitative and quantitative angiographic analysis was performed, and the volume of collected debris was estimated using a photographic technique. RESULTS: In our population, about 1/3 of the cases showed FNR, which was associated with angiographically visible filling defects within the basket, indicating macroembolism. However some patients (especially those undergoing vein graft interventions) showed filling defects without FNR, and some others FNR without filling defects. Thus we tried to understand the predictors of FNR: FNR was associated with higher amount of collected debris (36.97 +/- 42.98 mm(3) vs. 11.31 +/- 18.47 mm(3), p = 0.005), was neither prevented by abciximab, nor predicted by high thrombotic burden, increasing stent volume or need for predilatation. When patient with and without angiographically evident macroembolisation were separately analyzed, a linear correlation of FNR with the quantity of debris was only apparent in the macroembolization group. CONCLUSIONS: Interventionalists should be aware of the "Filter No Reflow", a common but reversible angiographic complication when the Filterwire device is used. Reduced flow seen during these procedures should be treated conservatively. Mechanical obstruction of the filter, but also other mechanisms (pharmacologically active debris? platelet aggregates?) play a role in this phenomenon.

Characterization of aortic root atherosclerosis in ApoE knockout mice: high-resolution in vivo and ex vivo MRM with histological correlation.

In vivo, cardiac-gated, black-blood, and ex vivo magnetic resonance microscopy (MRM) images of the aortic root, and histopathology data were obtained from 12 transgenic and wild-type (WT) mice. MRM was performed using a black-blood imaging spin-echo sequence with upstream and downstream in-flow saturation pulses to obtain aortic root images in three contrast techniques: proton density-weighted (PDW), T(1)- (T(1)W), and T(2)-weighted (T(2)W). Aortic wall thickness and area were measured and correlated with histopathology data (R > 0.90). Ex vivo lesion components (lipid core, fibrous tissue, and cell tissue) were identified and characterized by differing image contrast in PDW, T(1)W, and T(2)W MRM, and by histopathology. The differences between WT and transgenic mice for maximal wall thickness and area were statistically significant (P < 0.05). This study demonstrates the feasibility of in vivo murine aortic root lesion assessment and ex vivo plaque characterization by MRM.

Elevating high-density lipoprotein cholesterol in apolipoprotein E-deficient mice remodels advanced atherosclerotic lesions by decreasing macrophage and increasing smooth muscle cell content.

BACKGROUND: HDL cholesterol levels are inversely correlated with coronary heart disease risk in humans, and in animal studies, HDL elevation decreases formation and progression of foam-cell lesions. The potential for HDL to affect preexisting advanced atherosclerotic lesions is not known. To approach this issue, we used a novel mouse aortic transplantation model. METHODS AND RESULTS: ApoE-deficient (EKO) mice were fed a Western-type diet for 6 months, and thoracic aortic segments containing advanced lesions replaced segments of the abdominal aorta of 4-month-old EKO syngeneic mice not expressing (plasma HDL cholesterol approximately 26 mg/dL) or expressing (HDL approximately 64 mg/dL) a human apoAI (hAI) transgene. Both types of recipients had comparable non-HDL cholesterol levels. Five months after transplantation, mice were killed and grafts analyzed. Compared with lesion area in pretransplant mice (0.14+/-0.04 mm(2), mean+/-SEM), there was progression in the EKO recipients (0.39+/-0.06 mm(2), P<0.01). Compared with EKO recipients, hAI/EKO recipients had retarded progression (0.24+/-0.04 mm(2), P<0.05). Immunostaining for CD68 and other macrophage-associated proteins, monocyte chemoattractant protein-1, acyl coenzyme A:cholesterol acyltransferase, and tissue factor, in lesions of pretransplant and EKO recipient mice showed abundant macrophages. In contrast, compared with any other group, lesional macrophage area in hAI/EKO mice decreased >80% (P<0.003), and smooth muscle cell content (alpha-actin staining) increased >300% (P<0.006). The decrease in macrophages and increase in smooth muscle cells was primarily in the superficial subendothelial layer. CONCLUSIONS: Increasing HDL cholesterol levels in EKO mice retards progression of advanced atherosclerotic lesions and remodels them to a more stable-appearing phenotype.

An audit of lipid screening and management in patients undergoing diagnostic cardiac catheterization. Brompton House Officer Audit Group.

The aim of this study was to audit the management of hyperlipidaemia in a cohort of 206 consecutive patients, with known or suspected coronary artery disease, referred for diagnostic coronary angiography. The association of lipid subfraction values with the presence and extent of coronary artery disease was explored to identify the indices of greatest potential value to the hospital cardiologist, in the management of secondary prevention. Patients were questioned about previous lipid tests performed, advice received and treatment prescribed. Referral letters and hospital notes were reviewed to identify documentation of lipid results and treatment strategies. De novo fasting lipid estimations were obtained on 205 subjects at the time of catheterization. In only 46/206 (22%) cases was some form of lipid result recorded in the existing hospital notes or referral documentation. No patient was aware of the levels of the high or low density lipoprotein cholesterol subfractions (HDL, LDL) nor were these specifically recorded, or the subject of clinical comment, in any of the referral documentation. Patients who knew their total cholesterol (in mmol.1-1) result either as a value or as a "high' or "normal' categorization proved accurate witnesses. In keeping with other angiographic studies, we found that low values of HDL and high TC/HDL ratios were significantly associated with both disease presence and extent. Total cholesterol, calculated LDL and triglyceride levels had no such association. In the group as a whole and despite current therapy, 169/206 (82%) patients had a total cholesterol > 5.2 and 163/206 (79%) a TC/HDL ratio > 5. Only 22 (11%) patients were on drug therapy with a further 43 (21%) practising dietary modification. In the vast majority of subjects receiving some form of lipid intervention, target lipid levels had not been achieved. This study identifies the need for more intensive management of hyperlipidaemia in patients with coronary artery disease. Knowledge of HDL levels may be of value in guiding lipid secondary prevention management in the patient population evaluated at an angiographic centre.

Endothelial cell seeding fails to attenuate intimal thickening in balloon-injured rabbit arteries.

BACKGROUND: Restenosis of arteries or bypass grafts after vascular reconstruction is a common clinical entity that significantly limits long-term patency. This process, termed intimal hyperplasia (IH), is characterized by smooth muscle cell proliferation in the intima and subsequent accumulation of intercellular matrix. This study was designed to test the hypothesis that endothelial cell (EC) seeding of acutely injured arteries accelerates reendothelialization of the flow surface and limits the development of IH. METHODS: ECs were harvested from jugular veins of New Zealand white rabbits (n = 13) and were amplified in tissue culture. Each animal subsequently underwent bilateral balloon catheter injury of the iliofemoral arteries; one side was immediately seeded with cultured autologous ECs at supraconfluent density, whereas the contralateral vessel served as a nonseeded control. Animals were killed 33 +/- 5 days after balloon injury. Intimal thickening was quantitated on histologic sections of vessels (three sections per vessel, total of 60 sections) and percent endothelialization was assessed by SEM; measurements were obtained by use of computer-aided morphometry performed by a blinded observer. Data were analyzed by use of a paired t test for comparison between seeded and control vessels. RESULTS: Seeded vessels exhibited a greater degree of reendothelialization (93.9% +/- 7.6% of the surface) than their unseeded counterparts (65.1% +/- 22.5%, p < 0.01). Intimal cross-sectional area and the ratio of intimal area to medial area were not significantly different between seeded and control vessels (intima: 0.32 +/- 0.19 vs 0.37 +/- 0.11 mm2, p = 0.28; intimal area to medial area ratio: 0.84 +/- 0.35 vs 1.02 +/- 0.2, p = 0.24). CONCLUSIONS: We conclude that seeding with autologous venous ECs accelerated restoration of the endothelial monolayer but failed to attenuate IH in balloon-injured rabbit arteries. Further studies are necessary to determine the functional properties of seeded endothelium and to examine the effect of EC seeding on intimal thickening in other clinically relevant models.

An examination of needlestick injury rates, hepatitis B vaccination uptake and instruction on 'sharps' technique among medical students.

A 12-question survey designed to examine venepuncture techniques and instruction and uptake of hepatitis B vaccination was completed by 172 of the 275 medical students to whom it was distributed (a response rate of 62.5%). Seventy-five injuries were reported, at an average of 0.3 per student per year. Of the respondents, 63% resheathed needles after use, a practice frequently cited as a cause of needlestick injury. However, in this sample resheathing was not significantly associated with a higher or lower injury rate (chi 2 = 2.07, P > 0.1). Of the respondents from the most recent intake, only 20 out of 57 had completed a course of hepatitis B vaccinations prior to the commencement of venepuncture duties. There was almost universal ignorance concerning the correct course of action following 'sharps' injury. Recommendations are made concerning hepatitis B vaccination and teaching strategies for medical students.

Characterisation of inflammatory cells associated with "idiopathic retroperitoneal fibrosis".

During ureterolysis in a patient with "idiopathic retroperitoneal fibrosis", fresh samples of peri-ureteric and peri-aortic tissue were obtained. An abdominal CT scan confirmed the peri-aortic distribution of the inflammation associated with advanced abdominal aortic atherosclerosis. Histology confirmed the presence of fibrosis and a variable chronic inflammatory cell infiltrate. Monoclonal antibodies were used to identify the inflammatory cells. B and T lymphocytes were present with the majority of T lymphocytes of the T helper phenotype. The majority of lymphocytes and macrophages and most vascular endothelial cells were HLA-DR positive. Ki67 and BerH2 staining was found in B cells and T helper cells, indicating that these cells were proliferating and activated. These findings compare with the characterisation of inflammatory cells associated with "inflammatory aneurysms" and with the inflammatory cells present in the spectrum of inflammation seen as a complication of advanced atherosclerosis--conditions known as "chronic peri-aortitis". It is suggested that our findings support the view that idiopathic retroperitoneal fibrosis represents clinical chronic peri-aortitis seen in an undilated aorta.