LIVER RESECTION FOR NON-ORIENTAL HEPATOLITHIASIS

ABSTRACT Background: Primary intrahepatic lithiasis is defined when the stones are formed in the liver and associated with local dilatation and biliary stricture. Liver resection is the ideal procedure. Aim: To evaluate the results of liver resection in the treatment of non-oriental intrahepatic lithiasis. Methods: Fifty-one patients with symptomatic benign non-oriental hepatolithiasis underwent surgical resection in six institutions in Brazil. Demography data, clinical symptoms, classification, diagnosis, management and postoperative course were analyzed. Results: Of the 51 patients, 28 were male (54.9%), with a mean age of 49.3 years. History of cholangitis was observed in 15 (29.4%). The types of intrahepatic lithiasis were type I in 39 (76.5%) and type IIb in 12 (23.5%), with additional type Ea in six (11.8%). Liver function test were normal in 42 patients (82.4%). Segmental atrophy was observed in 12 (23.5%). Treatments included left lateral sectionectomy in 24 (47.1%), left hepatectomy in 14 (27.5%) and right hepatectomy in eight (15.7%), with associated hepaticojejunostomy in four (7.8%). Laparoscopic liver resection was performed in eight (15.7%). Postoperative complications were observed in 20 (39.2%) with no mortality. Conclusion: Liver resection in patients with hepatolithiasis is the ideal procedure as it removes stones, stricture, atrophic parenchyma, and minimizes the risk of cholangiocarcinoma.

Effect of compressibility on the small-scale structures in isotropic turbulence

Using a simulated highly compressible isotropic turbulence field with turbulent Mach number around 1.0, we studied the effects of local compressibility on the statistical properties and structures of velocity gradients in order to assess salient small-scale features pertaining to highly compressible turbulence against existing theories for incompressible turbulence. A variety of statistics and local flow structures conditioned on the local dilatation – a measure of local flow compressibility – are studied. The overall enstrophy production is found to be enhanced by compression motions and suppressed by expansion motions. It is further revealed that most of the enstrophy production is generated along the directions tangential to the local density isosurface in both compression and expansion regions. The dilatational contribution to enstrophy production is isotropic and dominant in highly compressible regions. The emphasis is then directed to the complicated properties of the enstrophy production by the deviatoric strain rate at various dilatation levels. In the overall flow field, the most probable eigenvalue ratio for the strain rate tensor is found to be −3:1:2.5, quantitatively different from the preferred eigenvalue ratio of −4:1:3 reported in incompressible turbulence. Furthermore, the strain rate eigenvalue ratio tends to be −1:0:0 in high compression regions, implying the dominance of sheet-like structures. The joint probability distribution function of the invariants for the deviatoric velocity gradient tensor is used to characterize local flow structures conditioned on the local dilatation as well as the distribution of enstrophy production within these flow structures. We demonstrate that strong local compression motions enhance the enstrophy production by vortex stretching, while strong local expansion motions suppress enstrophy production by vortex stretching. Despite these complications, most statistical properties associated with the solenoidal component of the velocity field are found to be very similar to those in incompressible turbulence, and are insensitive to the change of local dilatation. Therefore, a good understanding of dynamics of the compressive component of the velocity field is key to an overall accurate description of highly compressible turbulence.

ON LOCAL DILATATION INVARIANCE

The relationship between local Weyl scaling invariant models and local dilatation invariant actions is critically scrutinized. While actions invariant under local Weyl scalings can be constructed in a straightforward manner, actions invariant under local dilatation transformations can only be achieved in a very restrictive case. The invariant couplings of matter fields to an Abelian vector field carrying a nontrivial scaling weight can be easily built, but an invariant Abelian vector kinetic term can only be realized when the local scale symmetry is spontaneously broken.

Spatiotemporal Measurement of Freezing-Induced Deformation of Engineered Tissues

In order to cryopreserve functional engineered tissues (ETs), the microstructure of the extracellular matrix (ECM) should be maintained, as well as the cellular viability since the functionality is closely related to the ECM microstructure. Since the post-thaw ECM microstructure is determined by the deformation of ETs during cryopreservation, freezing-induced deformation of ETs was measured with a newly developed quantum dot (QD)-mediated cell image deformetry system using dermal equivalents as a model tissue. The dermal equivalents were constructed by seeding QD-labeled fibroblasts in type I collagen matrices. After 24 h incubation, the ETs were directionally frozen by exposing them to a spatial temperature gradient (from 4°C to −20°C over a distance of 6 mm). While being frozen, the ETs were consecutively imaged, and consecutive pairs of these images were two-dimensionally cross-correlated to determine the local deformation during freezing. The results showed that freezing induced the deformation of ET, and its magnitude varied with both time and location. The maximum local dilatation was 0.006 s−1 and was always observed at the phase change interface. Due to this local expansion, the unfrozen region in front of the freezing interface experienced compression. This expansion-compression pattern was observed throughout the freezing process. In the unfrozen region, the deformation rate gradually decreased away from the freezing interface. After freezing/thawing, the ET experienced an approximately 28% decrease in thickness and 8% loss in weight. These results indicate that freezing-induced deformation caused the transport of interstitial fluid, and the interstitial fluid was extruded. In summary, the results suggest that complex cell-fluid-matrix interactions occur within ETs during freezing, and these interactions determine the post-thaw ECM microstructure and eventual post-thaw tissue functionality.