Liver structural transformation after partial hepatectomy and repeated partial hepatectomy in rats: A renewed view on liver regeneration

BACKGROUND The phenomenon of liver regeneration after partial hepatectomy(PH)is still a subject of considerable interest due to the increasing frequency of half liver transplantation on the one hand,and on the other hand,new surgical approaches which allow removal of massive space-occupying hepatic tumors,which earlier was considered as inoperable.Interestingly,the mechanisms of liver regeneration are extensively studied after PH but less attention is paid to the architectonics of the regenerated organ.Because of this,the question“How does the structure of regenerated liver differ from normal,regular liver?”has not been fully answered yet.Furthermore,almost without any attention is left the liver's structural transformation after repeated hepatectomy(of the re-regenereted liver).ATM To compare the architectonics of the lobules and circulatory bed of normal,regenerated and re-regenerated livers.METHODS The livers of 40 adult,male,albino Wistar rats were studied.14 rats were subjected to PH-the 1st study group(SG1);10 rats underwent repeated PH–the 2nd study group(SG2);16 rats were subjected to sham operation-control group(CG);The livers were studied after 9 months from PH,and after 6 months from repeated PH.Cytological(Schiff reaction for the determination of DNA concentration),histological(H&E,Masson trichrome,CK8 Immunohistochemical marker,transparent slides after Indian Ink injection,),morphometrical(hepatocytes areas,perimeters and ploidy)and Electron Microscopical(Scanning Electron Microscopy of corrosion casts)methods were used.RESULTS In the SG1 and SG2,the area of hepatocytes and their perimeter are increased compared to the CG(P<0.05).However,the areas and perimeters of the hepatocytes of the SG1 and SG2 groups reveal a lesser difference.In regenerated(SG1)and re-regenerated(SG2)livers,the hepatocytes form the remodeled lobules,which size(300-1200μm)exceeds the sizes of the lobules from CG(300-600μm).The remodeled lobules(especially the“mega-lobules”with the sizes 1000-1200μm)contain the transformed meshworks of the sinusoids,the part of which is dilated asymmetrically.This meshwork might have originated from the several portal venules(interlobular and/or inlet).The boundaries between the adjacent lobules(including mega-lobules)are widened and filled by connective tissue fibers,which gives the liver parenchyma a nodular look.In SG2 the unevenness of sinusoid diameters,as well as the boundaries between the lobules(including the mega-lobules)are more vividly expressed in comparison with SG1.The liver tissue of both SG1 and SG2 is featured by the slightly expressed ductular reaction.CONCLUSION Regenerated and re-regenerated livers in comparison with normal liver contain hypertrophied hepatocytes with increased ploidy which together with transformed sinusoidal and biliary meshworks form the remodeled lobulli.

Anomalous Laterally Stressed Kinetically Trapped DNA Surface Conformations

Up to now,the DNA molecule adsorbed on a surface was believed to always preserve its native structure.This belief implies a negligible contribution of lateral surface forces during and after DNA adsorption although their impact has never been elucidated.High-resolution atomic force microscopy was used to observe that stiff DNA molecules kinetically trapped on monomolecular films comprising one-dimensional periodically charged lamellar templates as a single layer or as a sublayer are oversaturated by sharp discontinuous kinks and can also be locally melted and supercoiled.We argue that kink/anti-kink pairs are induced by an overcritical lateral bending stress(>30 pNnm)inevitable for the highly anisotropic 1D-1D electrostatic interaction of DNA and underlying rows of positive surface charges.In addition,the unexpected kink-inducing mechanical instability in the shape of the template-directed DNA confined between the positively charged lamellar sides is observed indicating the strong impact of helicity.The previously reported anomalously low values of the persistence length of the surface-adsorbed DNA are explained by the impact of the surface-induced low-scale bending.The sites of the local melting and supercoiling are convincingly introduced as other lateral stress-induced structural DNA anomalies by establishing a link with DNA high-force mechanics.The results open up the study in the completely unexplored area of the principally anomalous kinetically trapped DNA surface conformations in which the DNA local mechanical response to the surface-induced spatially modulated lateral electrostatic stress is essentially nonlinear.The underlying rich and complex in-plane nonlinear physics acts at the nanoscale beyond the scope of applicability of the worm-like chain approximation.

Cranial nerve monitoring in endoscopic endonasal surgery of skull base tumors (observing of 23 cases)

Background:Preservation of anatomic integrity and function of the cranial nerves during the removal of skull base tumors is one of the most challenging procedures in endoscopic endonasal surgery.It is possible to use intraoperative mapping and identification of the cranial nerves in order to facilitate their preservation.The purpose of this study was to evaluate the effectiveness of intraoperative trigger electromyography in prevention of iatrogenic damage to the cranial nerves.Methods:Twenty three patients with various skull base tumors(chordomas,neuromas,pituitary adenomas,meningiomas,cholesteatomas)underwent mapping and identification of cranial nerves during tumor removal using the endoscopic endonasal approach in Department of Neurooncology of Federal State Autonomous Institution"N.N.Burdenko National Medical Research Center of Neurosurgery"of the Ministry of Health of the Russian Federation from 2013 to 2018.During the surgical interventions,mapping and identification of the cranial nerves were carried out using electromyography in triggered mode.The effectiveness of the method was evaluated based on a comparison with a control group(41 patients).Results:In the main group of patients,44 nerves were examined during surgery using triggered electromyography.During the study,the III,V,VI,VII,and XII cranial nerves were identified intraoperatively.Postoperative cranial nerve deficiency was observed in 5 patients in the study group and in 13 patients in the control group.The average length of hospitalization was 9 days.Conclusion:We did not receive statistically significant data supporting the fact that intraoperative identification of cranial nerves using trigger electromyography reduces the incidence of postoperative complications in the form of cranial nerve deficits(p=0.56),but the odds ratio(0.6)suggests a less frequent occurrence of complications in the study group.Based on our experience,the trigger electromyography methodology appears quite promising and requires further research.