Noninvasive in vivo measurement of vascular inflammation with F-18 fluorodeoxyglucose positron emission tomography

BACKGROUND: Fluorine 18 fluorodeoxyglucose (FDG) has been shown to accumulate in inflamed tissues. However, it is not known whether vascular inflammation can be measured noninvasively. The aim of this study was to test the hypothesis that vascular inflammation can be measured noninvasively by use of positron emission tomography (PET) with FDG. METHODS AND RESULTS: Inflamed atherosclerotic lesions were induced in 9 male New Zealand white rabbits via balloon injury of the aortoiliac arterial segment and exposure to a high cholesterol diet. Ten rabbits fed standard chow served as controls. Three to six months after balloon injury, the rabbits were injected with FDG (1 mCi/kg), after which aortic uptake of FDG was assessed (3 hours after injection). Biodistribution of FDG activity within aortic segments was obtained by use of standard well gamma counting. FDG uptake was also determined noninvasively in a subset of 6 live atherosclerotic rabbits and 5 normal rabbits, via PET imaging and measurement of standardized uptake values over the abdominal aorta. Plaque macrophage density and smooth muscle cell density were determined by planimetric analysis of RAM-11 and smooth muscle actin staining, respectively. Biodistribution of FDG within nontarget organs was similar between atherosclerotic and control rabbits. However, well counter measurements of FDG uptake were significantly higher within atherosclerotic aortas compared with control aortas (P < .001). Within the upper abdominal aorta of the atherosclerotic group (area of greatest plaque formation), there was an approximately 19-fold increase in FDG uptake compared with controls (108.9 +/- 55.6 percent injected dose [%ID]/g x 10(3) vs 5.7 +/- 1.2 %ID/g x 10(3) [mean +/- SEM], P < .001). In parallel with these findings, FDG uptake, as determined by PET, was higher in atherosclerotic aortas (standardized uptake value for atherosclerotic aortas vs control aortas, 0.68 +/- 0.06 vs 0.13 +/- 0.01; P < .001). Moreover, macrophage density, assessed histologically, correlated with noninvasive (PET) measurements of FDG uptake (r = 0.93, P < .0001). In contrast to this finding, FDG uptake did not correlate with either aortic wall thickness or smooth muscle cell staining of the specimens. CONCLUSION: These data show that FDG accumulates in macrophage-rich atherosclerotic plaques and demonstrate that vascular macrophage activity can be quantified noninvasively with FDG-PET. As such, measurement of vascular FDG uptake with PET holds promise for the noninvasive characterization of vascular inflammation.     

Noncompliance in hemodialysis: predictors and survival analysis

Noncompliance with hemodialysis (HD), depending on the definition, occurs in 2% to more than 50% of patients. To better understand predictors and outcomes of noncompliance, we evaluated patient characteristics associated with noncompliance and the impact of noncompliance on survival. Using data from two USRDS special studies, we identified 6,251 patients who were on dialysis for more than 1 year for inclusion in this study. Noncompliance was defined in four ways: skipping one or more HD sessions in a month, shortening by 10 or more minutes one or more HD sessions in a month, an interdialytic weight gain (IWG) of more than 5.7% of dry weight, or a serum phosphate (PO4) of greater than 7.5 mg/dL. Sociodemographic predictors of noncompliance were identified using logistic regression. Survival analysis was done using Cox proportional hazards models with adjustments for sociodemographics, comorbid conditions, and dose of HD. Overall, 8.5% of patients skipped HD, 20% shortened HD (7% three or more times), 10% had more than a 5.7% IWG, and 22% had a PO4 greater than 7.5. There was a significant correlation among the measures of noncompliance. Blacks (adjusted odds ratio [AOR] = 2.10), patients aged 20 to 39 years (AOR = 1.62), and smokers (AOR = 1.34) were significantly more likely to skip HD than whites, patients aged 40 to 59 years, and nonsmokers, respectively (P < 0.01 for each). Similar results were seen for the other measures of noncompliance, except for PO4, in which blacks were significantly less likely to be noncompliant (NC) (AOR = 0.85, P < 0.05). Compared with compliant patients, those who skipped one or more HD sessions in a month had a 25% higher risk of death (P < 0.01). Those who had greater than a 5.7% IWG had a 35% higher risk of death (P < 0.001), whereas those with a PO4 > 7.5 had a 13% higher risk of death (P < 0.05). Overall, patients who shortened HD sessions did not have a higher risk of death, but those who shortened three or more in 1 month had a 20% higher risk of death (P < 0.05). Compliance with a medical regimen is a complex issue. Noncompliance in HD often, but not always, is associated with a higher risk of an adverse outcome. This is a US government work. There are no restrictions on its use.     

维生素B6电化学反应机理的研究

用循环伏安法和计时库仑法研究了维生素B₆(VB₆)在不同pH值的磷酸盐介质中的电化学行为。结果表明:VB₆经过一个有质子参与的4e不可逆电氧化反应;在碱性和中性介质中VB₆被电氧化为含有羰基结构的自由基;在酸性介质中VB₆被电氧化为γ-内酯。电氧化的产物均具电活性,可分别发生两步准可逆氧化还原反应。化学鉴定实验表明在碱性和中性介质中VB₆氧化后生成羰基化合物,而在酸性介质中VB₆氧化后无羰基生成。紫外吸收光谱电化学实验结果表明:VB₆在碱性和中性介质条件下随电解时间而变化的吸收光谱与在酸性介质条件下的不一样。在此基础上提出了VB₆在不同pH介质条件下可能的电化学反应历程。     

鲎试剂用于5％甘露醇注射液的细菌内毒素检测

目的：研究5％甘露醇注射液的细茵内毒素检查方法。方法：通过干扰试验证明5％甘露醇注射液对λ=0.5EU/ml的鲎试剂元抑制和增强作用。结果：使用λ=0.5EU/ml的鲎试荆可直接取样进行检测。结论：5％甘露醇注射液可以甩细茸内毒素检查法取代热原检查法。     

Comparison of three IMRT inverse planning techniques that allow for partial esophagus sparing in patients receiving thoracic radiation therapy for lung cancer.

The purpose of this study is to compare 3 intensity-modulated radiation therapy (IMRT) inverse treatment planning techniques as applied to locally-advanced lung cancer. This study evaluates whether sufficient radiotherapy (RT) dose is given for durable control of tumors while sparing a portion of the esophagus, and whether large number of segments and monitor units are required. We selected 5 cases of locally-advanced lung cancer with large central tumor, abutting the esophagus. To ensure that no more than half of the esophagus circumference at any level received the specified dose limit, it was divided into disk-like sections and dose limits were imposed on each. Two sets of dose objectives were specified for tumor and other critical structures for standard dose RT and for dose escalation RT. Plans were generated using an aperture-based inverse planning (ABIP) technique with the Cimmino algorithm for optimization. Beamlet-based inverse treatment planning was carried out with a commercial simulated annealing package (CORVUS) and with an in-house system that used the Cimmino projection algorithm (CIMM). For 3 of the 5 cases, results met all of the constraints from the 3 techniques for the 2 sets of dose objectives. The CORVUS system without delivery efficiency consideration required the most segments and monitor units. The CIMM system reduced the number while the ABIP techniques showed a further reduction, although for one of the cases, a solution was not readily obtained using the ABIP technique for dose escalation objectives.