Development and Evaluation of MR-Based Radiogenomic Models to Differentiate Atypical Lipomatous Tumors from Lipomas

Background: The aim of this study was to develop and validate radiogenomic models to predict the MDM2 gene amplification status and differentiate between ALTs and lipomas on preoperative MR images. Methods: MR images were obtained in 257 patients diagnosed with ALTs (n = 65) or lipomas (n = 192) using histology and the MDM2 gene analysis as a reference standard. The protocols included T2-, T1-, and fat-suppressed contrast-enhanced T1-weighted sequences. Additionally, 50 patients were obtained from a different hospital for external testing. Radiomic features were selected using mRMR. Using repeated nested cross-validation, the machine-learning models were trained on radiomic features and demographic information. For comparison, the external test set was evaluated by three radiology residents and one attending radiologist. Results: A LASSO classifier trained on radiomic features from all sequences performed best, with an AUC of 0.88, 70% sensitivity, 81% specificity, and 76% accuracy. In comparison, the radiology residents achieved 60–70% accuracy, 55–80% sensitivity, and 63–77% specificity, while the attending radiologist achieved 90% accuracy, 96% sensitivity, and 87% specificity. Conclusion: A radiogenomic model combining features from multiple MR sequences showed the best performance in predicting the MDM2 gene amplification status. The model showed a higher accuracy compared to the radiology residents, though lower compared to the attending radiologist.

An optically accessible pyrolysis microreactor

We report an optically accessible pyrolysis micro-reactor suitable for in situ laser spectroscopic measurements. A radiative heating design allows for completely unobstructed views of the micro-reactor along two axes. The maximum temperature demonstrated here is only 1300 K (as opposed to 1700 K for the usual SiC micro-reactor) because of the melting point of fused silica, but alternative transparent materials will allow for higher temperatures. Laser induced fluorescence measurements on nitric oxide are presented as a proof of principle for spectroscopic characterization of pyrolysis conditions.

The infrared spectrum of the matrix-isolated phenyl radical

We have measured the infrared absorption spectrum of C(6)H(5), /X (2)A(1), in an Ar matrix at 10 K. The experimental frequencies (cm(-)(1)) and polarizations follow. a(1) modes: 3086, 3072, 3037, 1581, 1441, 1154, 1027, 997, 976, 605; b(1) modes: 972, 874, 706, 657, 416; b(2) modes: 3071, 3060, 1624, 1432, 1321, 1283, 1159, 1063, and 587. Three different methods have been used for the production of the phenyl radicals. Infrared absorption spectra of five deuterated isotopomers, C(6)D(5), p-C(6)H(4)D, p-C(6)HD(4), o-C(6)H(4)D, and m-C(6)H(4)D, were recorded to compare experimental frequency shifts with calculated (UB3LYP/cc-pVDZ) harmonic frequency shifts. The use of CO(2) or NO as internal standards enabled the experimental determination of absolute infrared intensities. The linear dichroism was measured with photooriented samples to establish experimental polarizations of each vibrational band. True gas-phase vibrational frequencies were estimated by considering the gas-to-matrix shifts and matrix inhomogeneous line broadening. The phenyl radical matrix frequencies listed above are within +/-1% of the gas-phase vibrational frequencies. The C(6)H(5) frequencies from this paper supersede our earlier values reported in J. Am. Chem. Soc. 1996, 118, 7400-7401. See also: http://ellison.colorado.edu/phenyl.

Breakpoint sequences of an 1;8 translocation in a family with Gilles de la Tourette syndrome

Gilles de la Tourette syndrome (GTS) is a common, heritable neurological disorder manifested by chronic motor and vocal tics with childhood onset. Previous extensive linkage analysis failed to identify a GTS gene based on an autosomal dominant pattern of inheritance. Recently, a family was reported with a balanced chromosomal translocation t(1;8)(q21.1;q22.1) in family members with GTS or tics. Chromosome 8q22.1 was previously implicated in GTS by both association and linkage results. We therefore cloned and sequenced both translocation breakpoints from this family. The CBFA2T1 gene was identified 11 kb distal to the 8q22.1 breakpoint. Sequencing of CBFA2TI exons within 37 unrelated GTS patients failed to identify any mutations. However, it is possible that the translocation altered the expression of this gene or another nearby gene. Examination of the breakpoint sequences revealed a duplication of six nucleotides from chromosome 8 but no change in the chromosome 1 sequence. The sequences immediately flanking the breakpoints on the two chromosomes were modestly similar, but the breakpoints did not occur within known interspersed repeats. Our results add to our knowledge of the genetics of GTS and the mechanisms of balanced chromosomal translocations.

Relationship of thrombohemorrhagic complications to endothelial cell function in patients with chronic myeloproliferative disorders

Thrombotic and hemorrhagic disorders are common complications of the myeloproliferative disorders. Endothelial cells release both procoagulant and profibrinolytic factors, which may contribute to these hemorrhagic or thrombotic complications. The pre- and postvenous stasis levels of the procoagulant and profibrinolytic factors produced by endothelial cells were correlated with the occurrence of complications in polycythemia rubra vera (PRV) patients (n = 29) and essential thrombocythemia (ET) patients (n = 17) compared with normal patients (n = 17). Tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor (PAI) activity, von Willebrand's factor (vWF) activity and antigen (vWF:Ag), and factor VIII activity were measured. The resting tPA activity was significantly higher in the two disease groups compared with normal controls, but no difference between the levels of tPA and either complication within the disease groups was observed. Significantly elevated tPA following venous stasis was observed in the patients of both disease groups who had bleeding complications. Significant decreases, compared with the normal group, in both resting and postvenous stasis levels of PAI were observed in the disease groups regardless of complication history. The subjects from both disease groups with thrombotic complications had significantly elevated resting vWF and both resting and postvenous stasis vWF:Ag levels compared with normal controls. The endothelial cell is likely to be responding to abnormal hemostasis rather than being primarily involved in the genesis of a hyper- or hypocoaguable state.