A new method is developed in which a circular dichroism (CD) spectrum is analyzed directly as a linear combination of the CD spectra (from 190 to 240 nm) of 16 proteins whose secondary structures are known from X-ray crystallography. This avoids the dilemma encountered in previous methods of trying to define single reference CD spectra that were supposed to characterize such broad and variable classes as helix, beta sheet, beta turn, and "remainder". It also permits a more accurate and flexible analysis. The usual instability in using so many parameters is automatically controlled by a simple constrained statistical regularization procedure (similar to ridge regression). Sixteen tests were made by removing 1 spectrum at a time from the set of 16 and analyzing it in terms of the other 15. The product moment correlation coefficients between the computed fractions of helix, beta sheet, beta turn, and remainder and the fractions from the X-ray data were 0.96, 0.94, 0.31,, and 0.49, respectively. Thus, the helix and beta-sheet accuracy is very good. (The corresponding values calculated by a previous method with four reference spectra were 0.85, 0.25, --0.31, and 0.46.).

MR measures of renal and cyst volume are reliable and accurate in patients with ADPKD. ADPKD is characterized by significant cystic involvement that increases with age. Structure (renal and cyst volume) and function (GFR) are inversely related and directly related with the presence of hypertension and urinary albumin excretion in individuals with normal renal function.

LGE is common in CA and detects interstitial expansion from amyloid deposition. Global transmural or subendocardial LGE is most common, but suboptimal myocardial nulling and focal patchy LGE are also observed. LGE-CMR may detect early cardiac abnormalities in patients with amyloidosis with normal left ventricular thickness. The presence and pattern of LGE is strongly associated with clinical, morphologic, functional, and biochemical markers of prognosis.

Background-Myocardial late gadolinium enhancement (LGE) on contrast-enhanced magnetic resonance imaging (CE-MRI) of patients with hypertrophic cardiomyopathy (HCM) has been suggested to represent intramyocardial fibrosis and, as such, an adverse prognostic risk factor. We evaluated the characteristics of LGE on CE-MRI and explored whether LGE among patients with HCM was associated with genetic testing, severe symptoms, ventricular arrhythmias, or sudden cardiac death (SCD LGE positive (event rate of 0.94%/y, Pϭ0.01 versus LGE negative). Two additional heart failure-related deaths were recorded among LGE-positive patients. Univariate associates of SCD or appropriate ICD discharge were positive LGE (Pϭ0.002) and presence of nonsustained ventricular tachycardia (Pϭ0.04). The association of LGE with events remained significant after controlling for other risk factors. Conclusions-In patients with HCM, presence of LGE on CE-MRI was common and more prevalent among gene-positive patients.LGE was not associated with severe symptoms. However, LGE was strongly associated with surrogates of arrhythmia and remained a significant associate of subsequent SCD and/or ICD discharge after controlling for other variables. If replicated, LGE may be considered an important risk factor for sudden death in patients with HCM. (Circ Heart Fail. 2010;3:51-58.)

Aim-To evaluate the potential value of magnetic resonance elastography (MRE) for characterizing solid liver tumors.Materials and Methods-Forty-four liver tumors (metastases-14, hepatocellular carcinoma-12, hemangioma-9, cholangiocarcinoma-5, focal nodular hyperplasia-3, and hepatic adenoma-1) were evaluated with MRE. MRE was performed on a 1.5 T scanner with a modified phase-contrast, gradient echo sequence to collect axial wave images sensitized along the through-plane motion direction. The tumors were identified in T2-, T1-weighted and gadolinium enhanced T1-weighted images and the MRE images were obtained through the tumor. A stiffness map (elastogram) was generated by an automated process using an inversion algorithm. The mean shear stiffness of the tumor was calculated using a manually specified region of interest placed over the tumor in the stiffness map. The stiffness value of non-tumor bearing hepatic parenchyma was also calculated. Statistical analysis was performed on the stiffness values for differentiation between normal liver, fibrotic liver, benign tumors and malignant tumors.Results-Malignant liver tumors had significantly higher mean shear stiffness than benign tumors, fibrotic liver and normal liver (10.1kPa vs. 2.7kpa (p<0.001), vs. 5.9kPa (p<0.001) and vs. 2.3kPa (p<0.001) respectively). Fibrotic livers had stiffness values overlapping both the benign and malignant tumors. Cut-off values of 5kPa accurately differentiate malignant tumors from benign tumors and normal liver parenchyma in this preliminary investigation.Conclusions-MR elastography is a promising, non-invasive technique for assessing solid liver tumors. MRE may provide new, quantitative tissue characterization parameters for differentiating benign and malignant liver tumors.