Carotid artery calcification on CT may independently predict stroke risk.

OBJECTIVE: The purpose of our study was to quantitatively evaluate calcified atherosclerotic burden in the cervical carotid arteries using MDCT to determine the relationship of scores with luminal stenosis and symptomatology. MATERIALS AND METHODS: Calcium plaque volume was measured in 106 cervical carotid arteries (53 patients) using MDCT angiography. The study group included 32 asymptomatic patients (mean age, 70.2 +/- 8.7 [SD] years; 15 women, 17 men) and 21 patients with ischemic neurologic symptoms (69.6 +/- 12.9 years; eight women, 13 men). By vessel, there were 43 high-grade stenotic (> or = 60% by North American Symptomatic Carotid Endarterectomy Trial [NASCET] criteria), 15 moderate-grade stenotic (30-59%), and 44 mild-grade stenotic or normal (0-29%) vessels, with four excluded for prior carotid endarterectomy. Volume scores were calculated by summing the area of calcium in the common and extracranial internal carotid arteries on axial slices and multiplying by the slice increment. RESULTS: Controlling for cardiovascular risk factors and luminal stenosis, we found that scores were significantly related to the occurrence of symptoms (p = 0.003). Even with patient age as a covariant, patients with high-grade stenosis had significantly higher scores than those without high-grade disease (p = 0.004). Moreover, quantitative burden was associated with luminal stenosis on adjusted multivariate analysis (p = 0.034). The specificity and positive predictive value for high-grade luminal narrowing were notably lower on individual vessel analysis than on total score analysis, likely secondary to variability in vascular remodeling. CONCLUSION: Calcium scores in the cervical carotid arteries may represent an independent marker for luminal stenosis and ischemic symptoms. A prospective longitudinal study examining calcium levels and morbidity may be warranted to examine whether burden has a role in risk stratification.

Accuracy of computed tomography attenuation values in the characterization of pleural fluid: an ROC study.

RATIONALE AND OBJECTIVES: To assess the accuracy of computed tomography (CT) in characterizing pleural fluid based on attenuation values. MATERIALS AND METHODS: Protocol was approved by the local institutional review board and informed consent was waived. We retrospectively analyzed 145 pleural effusions of 145 patients (mean/standard deviation age: 60.7/15.9 years; 69 females) who underwent CT of the thorax and diagnostic thoracentesis within 7 days of each other. Effusions were classified as transudates or exudates using laboratory markers based on Light's criteria. The mean Hounsfield units (HU) of an effusion was determined by a region of interest on the three slices with the greatest anteroposterior diameter. A receiver operating characteristic curve was constructed to determine threshold values for classification on the basis of mean HU and to examine overall accuracy, using the area under the curve (A(z)). RESULTS: Of the 101 exudates and 44 transudates, the mean attenuation of exudates (17.1 HU/standard deviation 4.4) was significantly higher than transudates (12.5 HU/6.3), (P < .001). There was a modest but significant positive relationship between mean HU and laboratory markers, with the strongest relationship with pleural/serum protein (r = 0.57, P < .001) and total pleural protein (r = 0.56, P < .001). The overall accuracy of attenuation values for identifying exudates was moderate, Az = 0.775, standard error = 0.039, with the largest limitation being the overlap with transudates in the 10-20 HU range, which constituted 66% (90/145) of the total effusions measured. CONCLUSION: Although the mean attenuation of exudates is significantly higher than transudates, the clinical use of CT numbers to characterize pleural fluid is not recommended, as their accuracy is only moderate. Moreover, there is a notable overlap in attenuation values between transudates and exudates for a majority of effusions.

Effects at a distance in alpha 7 nAChR selective agonists: benzylidene substitutions that regulate potency and efficacy.

Anabaseine is a marine worm toxin that is a relatively non-selective nicotinic agonist, activating both muscle-type and neuronal nicotinic acetylcholine receptors (nAChR) with varying efficacy. While anabaseine has significant activity with muscle-type and neuronal alpha 3 beta 4 and alpha 4 beta 2 receptors, benzylidene anabaseine (BA) derivatives have high selectivity for the alpha 7 receptor subtype. Two BA compounds with substituents at the 2 and 4 positions of the benzylidene ring, GTS-21 and 4OH-GTS-21, may have therapeutic potential for treating neuropathological disorders such as Alzheimer's disease due to their alpha 7 selectivity. In this study, we specifically investigated the influence of the benzylidene attachment to anabaseine on alpha 7 nicotinic receptor selectivity, as well as the effects of specific substituents at the 4- position of the benzylidene moiety. We demonstrate that benzylidene-attachment alone is sufficient to confer alpha 7 selectivity to anabaseine. Increased potency and receptor binding affinity was obtained with a 4-hydroxyl substitution. Two other 4-substituted benzylidene anabaseines, 3-(4'-methylthiobenzylidene)anabaseine (4-MeS-BA) and 3-(4-trifluoromethylbenzylidene) anabaseine (4-CF(3)-BA), offered very little agonist activity for any nicotinic receptors and instead were antagonists for both alpha 7 and neuronal alpha 3 beta 4 and alpha 4 beta 2 receptors. Since the relative amounts of agonist and antagonist activities for specific BA compounds vary with the specific drug/receptor combinations, benzylidene anabaseines provide valuable tools for nAChR drug-receptor structure-function relationships.