Findings in multidetector computed tomography in the diagnosis of hepatocellular carcinoma in patients with cirrhosis and correlation with pathology of liver explants

Objetivos: Describir el comportamiento imagenológico del hepatocarcinoma en pacientes con cirrosis utilizando la tomografía computada multidetector (TCMD) dinámica y correlacionar los hallazgos con el grado histológico de los tumores. Materiales y métodos: Estudio retrospectivo, observacional y descriptivo, donde se evaluaron 51 nódulos de 32 pacientes trasplantados de hígado con diagnóstico de cirrosis. La anatomía patológica del explante fue utilizada como referencia y los nódulos con histología de hepatocarcinoma fueron analizados retrospectivamente en las tomografías computadas efectuadas antes del trasplante. Las tomografías se llevaron a cabo con técnica dinámica, evaluando las características más frecuentes reportadas en la literatura: realce arterial, lavado del realce, cápsula y vasos arteriales intratumorales. Resultados: Cuarenta y seis de 51 (90%) tumores mostraron realce arterial. De estos 46 tumores, 39 (85%) mostraron lavado del realce en la fase portal y/o tardía. De los 51, 5 (10%) fueron hipovasculares, 22 (43%) presentaron cápsula y 12 (24%) mostraron vasos arteriales intratumorales. La combinación de hallazgos más frecuente fue la asociación de realce arterial y lavado del realce en la fase portal-tardía (39/51 tumores: 76%), y el grado histológico más usual fue el II en 35 tumores (69%). Se hallaron asociaciones estadísticamente significativas entre el grado histológico de los tumores y los comportamientos imagenológicos realce arterial e hipovascular. Conclusión: En nuestra población, el hallazgo tomográfico de realce arterial con lavado del realce en tiempo portal y/o tardío fue observado en la mayoría de los tumores. Esto coincide con publicaciones anteriores y contribuye a fortalecer el valor de estos criterios para el diagnóstico del hepatocarcinoma.Objectives: To describe the imagenological behavior of hepatocellular carcinoma in cirrhotic patients using a dynamic multidetector computed tomography (MDCT) technique, and correlate these À ndings with histological tumor grades. Materials and methods: A retrospective, descriptive observational study was conducted to evaluate 51 nodules in 32 liver transplant patients diagnosed with liver cirrhosis. The pathology of liver explants was used as a reference. Nodules with hepatocellular carcinoma histopathology were retrospectively analyzed by computed tomography scans performed pre-transplant. Using a dynamic multidetector computed tomography technique, we evaluated the most common imagenological behavior reported in the literature: arterial enhancement, washout, capsule, and intratumoral arterial vessels. Results: Forty-six of 51 (90%) tumors showed arterial enhancement. Of the 46 tumors with arterial enhancement, 39 (85%) had washout in portal-late phase. Five of 51 (10%) were hypovascular. Twenty-two of 51 (43%) had capsule and 12 of 51 (24%) showed intratumoral arterial vessels. The more frequent image combination was the combination of arterial enhancement and washout (39 of 51 tumors or 76%). The most frequent histological grade was II (35 of 51 tumors or 69%). Statistically signiÀ cant relationships were found between histological grade tumors and imagenological behavior: arterial enhancement and hypovascular. Conclusion: In our population, arterial enhancement with washout in portal-late phases was observed in most of the tumors. Our results are consistent with previously reported studies, demonstrating the high reliability of this imaging pattern for the diagnosis of hepatocellular carcinoma.Fil: Haberman, D. Fundación Favaloro; ArgentinaFil: Castignola, M. Fundación Favaloro; ArgentinaFil: Mela, M. Fundación Favaloro; ArgentinaFil: Paladini, H. Fundación Favaloro; ArgentinaFil: Santilli, J. P. Fundación Favaloro; ArgentinaFil: Gruz, F. Fundación Favaloro; ArgentinaFil: Gondolesi, Gabriel Eduardo. Fundación Favaloro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The 3′–5′ proofreading exonuclease of archaeal family-B DNA polymerase hinders the copying of template strand deaminated bases

Archaeal family B polymerases bind tightly to the deaminated bases uracil and hypoxanthine in single-stranded DNA, stalling replication on encountering these pro-mutagenic deoxynucleosides four steps ahead of the primer–template junction. When uracil is specifically bound, the polymerase–DNA complex exists in the editing rather than the polymerization conformation, despite the duplex region of the primer-template being perfectly base-paired. In this article, the interplay between the 3′–5′ proofreading exonuclease activity and binding of uracil/hypoxanthine is addressed, using the family-B DNA polymerase from Pyrococcus furiosus. When uracil/hypoxanthine is bound four bases ahead of the primer–template junction (+4 position), both the polymerase and the exonuclease are inhibited, profoundly for the polymerase activity. However, if the polymerase approaches closer to the deaminated bases, locating it at +3, +2, +1 or even 0 (paired with the extreme 3′ base in the primer), the exonuclease activity is strongly stimulated. In these situations, the exonuclease activity is actually stronger than that seen with mismatched primer-templates, even though the deaminated base-containing primer-templates are correctly base-paired. The resulting exonucleolytic degradation of the primer serves to move the uracil/hypoxanthine away from the primer–template junction, restoring the stalling position to +4. Thus the 3′–5′ proofreading exonuclease contributes to the inability of the polymerase to replicate beyond deaminated bases

K0s K0s Final State in Two-Photon Collisions and Implications for Glueballs

The K0s K0s final state in two-photon collisions is studied with the L3 detector at LEP. The mass spectrum is dominated by the formation of the f_2'(1525) tensor meson in the helicity-two state with a two-photon width times the branching ratio into K Kbar of 76 +- 6 +- 11 eV. A clear signal for the formation of the f_J(1710) is observed and it is found to be dominated by the spin-two helicity-two state. No resonance is observed in the mass region around 2.2 GeV and an upper limit of 1.4 eV at 95% C.L. is derived for the two-photon width times the branching ratio into K0s K0s for the glueball candidate xi(2230)

Glibenclamide—10-h Treatment Window in a Clinically Relevant Model of Stroke

Glibenclamide improves outcomes in rat models of stroke, with treatment as late as 6 h after onset of ischemia shown to be beneficial. Because the molecular target of glibenclamide, the sulfonylurea receptor 1 (Sur1)-regulated NCCa-ATP channel, is upregulated de novo by a complex transcriptional mechanism, and the principal pathophysiological target, brain swelling, requires hours to develop, we hypothesized that the treatment window would exceed 6 h. We studied a clinically relevant rat model of stroke in which middle cerebral artery occlusion (75% < reduction in LDF signal ≤90%) was produced using an intra-arterial occluder. Recanalization was obtained 4.5 h later by removing the occluder. At that time, we administered recombinant tissue plasminogen activator (rtPA; 0.9 mg/kg IV over 30 min). Immunolabeling showed modest expression of Sur1 5 h after onset of ischemia, with expression increasing 7- to 11-fold (P < 0.01) by 24 h. Rats were administered either vehicle or glibenclamide (10 μg/kg IP loading dose plus 200 ng/h by constant subcutaneous infusion) beginning 4.5 or 10 h after onset of ischemia. In rats treated at 4.5 or 10 h, glibenclamide significantly reduced hemispheric swelling at 24 h from (mean ± SEM) 14.7 ± 1.5% to 8.1 ± 1.6% or 8.8 ± 1.1% (both P < 0.01), respectively, and significantly reduced 48-h mortality from 53% to 17% or 12% (both P < 0.01), and improved Garcia scores at 48 h from 3.8 ± 0.62 to 7.6 ± 0.70 or 8.4 ± 0.74 (both P < 0.01). We conclude that, in a clinically relevant model of stroke, the treatment window for glibenclamide extends to 10 h after onset of ischemia

A nucleotide binding rectification Brownian ratchet model for translocation of Y-family DNA polymerases

Y-family DNA polymerases are characterized by low-fidelity synthesis on undamaged DNA and ability to catalyze translesion synthesis over the damaged DNA. Their translocation along the DNA template is an important event during processive DNA synthesis. In this work we present a Brownian ratchet model for this translocation, where the directed translocation is rectified by the nucleotide binding to the polymerase. Using the model, different features of the available structures for Dpo4, Dbh and polymerase ι in binary and ternary forms can be easily explained. Other dynamic properties of the Y-family polymerases such as the fast translocation event upon dNTP binding for Dpo4 and the considerable variations of the processivity among the polymerases can also be well explained by using the model. In addition, some predicted results of the DNA synthesis rate versus the external force acting on Dpo4 and Dbh polymerases are presented. Moreover, we compare the effect of the external force on the DNA synthesis rate of the Y-family polymerase with that of the replicative DNA polymerase