Editorial: Conflicts

The Editorial Board reflects on the theme of 'conflict', as observed in the work published in this issue, and in the wider world

Role of PSCs in Regeneration of Remnant Pancreas after PX

Background and objectives Mechanism of regeneration of remnant pancreas after partial pancreatectomy (PX) is still unknown. In this study, effect of siRNA against the collagen specific chaperone, HSP47, which inhibits collagen secretion from activated pancreas stellate cells (aPSCs), and induces their apoptosis, on regeneration of remnant pancreas was determined. Methods Pancreatectomy was performed according to established methods. Proliferation of cells was assessed by BrdU incorporation. Immunostaining of HSP47 was employed to identify PSCs. Progenitor cells were identified by SOX9 staining. Acinar cells were immunostained for amylase. Co-culture of acinar cells with aPSCs were carried out in a double chamber with a cell culture insert. siRNA HSP47 encapsulated in vitamin A-coupled liposome (VA-lip siRNA HSP47) was delivered to aPSCs by iv injection. Results In remnant pancreas of 90% PX rat, new areas of foci were located separately from duodenal areas with normal pancreatic features. After PX, BrdU uptake of acinar cells and islet cells significantly increased, but was suppressed by treatment with VA-lip siRNA HSP47. BrdU uptake by acinar cells was augmented by co-culturing with aPSCs and the augmentation was nullified by siRNA HSP47. BrdU uptake by progenitor cells in foci area was slightly enhanced by the same treatment. New area which exhibited intermediate features between those of duodenal and area of foci, emerged after the treatment. Conclusion aPSCs play a crucial role in regeneration of remnant pancreas, proliferation of acinar and islet cells after PX through the activity of secreted collagen. Characterization of new area emerged by siRNA HSP47 treatment as to its origin is a future task

Enhancement of B- and C-Scan Images of C-Sam with an Acoustic Matching Layer

Ultrasonic immersion methods have been used for nondestructive evaluation of material properties as well as for B- or C-scan imaging of internal microstructure and/or defects. However, the direct application of this method is difficult for dissolving or hygroscopic materials as well as rusting metals. Thin waterproof coating on such materials enables us to apply immersion methods for those materials and it is also effective for reducing reflection at the water/material interface, if the coating has an appropriate acoustic impedance.</p

A new design for posterior resin bonded bridges

Ultrasonic immersion methods have been used for nondestructive evaluation of material properties as well as for B- or C-scan imaging of internal microstructure and/or defects. However, the direct application of this method is difficult for dissolving or hygroscopic materials as well as rusting metals. Thin waterproof coating on such materials enables us to apply immersion methods for those materials and it is also effective for reducing reflection at the water/material interface, if the coating has an appropriate acoustic impedance

Characterization of the novel Trypanosoma brucei inosine 5′-monophosphate dehydrogenase

There is an alarming rate of human African trypanosomiasis recrudescence in many parts of sub-Saharan Africa. Yet, the disease has no successful chemotherapy. Trypanosoma lacks the enzymatic machinery for the de novo synthesis of purine nucleotides, and is critically dependent on salvage mechanisms. Inosine 5′-monophosphate dehydrogenase (IMPDH) is responsible for the rate-limiting step in guanine nucleotide metabolism. Here, we characterize recombinant Trypanosoma brucei IMPDH (TbIMPDH) to investigate the enzymatic differences between TbIMPDH and host IMPDH. Size-exclusion chromatography and analytical ultracentrifugation sedimentation velocity experiments reveal that TbIMPDH forms a heptamer, different from type 1 and 2 mammalian tetrameric IMPDHs. Kinetic analysis reveals calculated K m values of 30 and 1300 μ m for IMP and NAD, respectively. The obtained K m value of TbIMPDH for NAD is approximately 20–200-fold higher than that of mammalian enzymes and indicative of a different NAD binding mode between trypanosomal and mammalian IMPDHs. Inhibition studies show K i values of 3·2 μ m, 21 nM and 3·3 nM for ribavirin 5′-monophosphate, mycophenolic acid and mizoribine 5′-monophosphate, respectively. Our results show that TbIMPDH is different from its mammalian counterpart and thus may be a good target for further studies on anti-trypanosomal drugs