Successful stent placement for hepatic venous outflow obstruction in pediatric living donor liver transplantation, including a case series review

Abstract:  HVOO may lead to graft dysfunction in LDLT. Balloon angioplasty is the first treatment for HVOO. However, some cases with recurrent HVOO need multiple interventions and require stent placement. The authors describe a pediatric case with recurrent HVOO requiring multiple stent placements. Her symptoms related to HVOO finally disappeared after the third stenting. A year later, follow-up liver biopsy did not show any dramatic change in perivenular fibrosis. From a review of our pediatric cases with HVOO requiring stent placement, the majority of them lost the grafts, because the timing of stent placement was too late to prevent the progression of fibrosis. In conclusion, stent placement should be considered in select cases of HVOO. Serial liver biopsies evaluating the degree of fibrosis are essential in determining the timing of stent placement.     

Preimplantation genetic diagnosis/screening by comprehensive molecular testing

Although embryo screening by preimplantation genetic diagnosis (PGD) has become the standard technique for the treatment of recurrent pregnancy loss in couples with a balanced gross chromosomal rearrangement, the implantation and pregnancy rates of PGD using conventional fluorescence in situ hybridization (FISH) remain suboptimal. Comprehensive molecular testing, such as array comparative genomic hybridization and next‐generation sequencing, can improve these rates, but amplification bias in the whole genome amplification method remains an obstacle to accurate diagnosis. Recent advances in amplification procedures combined with improvements in the microarray platform and analytical method have overcome the amplification bias, and the data accuracy of the comprehensive PGD method has reached the level of clinical laboratory testing. Currently, comprehensive PGD is also applied to recurrent pregnancy loss due to recurrent fetal aneuploidy or infertility with recurrent implantation failure, known as preimplantation genetic screening. However, there are still numerous problems to be solved, including misdiagnosis due to somatic mosaicism, cell cycle‐related background noise, and difficulty in diagnosis of polyploidy. The technology for comprehensive PGD also requires further improvement.     

Frequent cellular senescence in small bile ducts in primary biliary cirrhosis: a possible role in bile duct loss

The pathogenesis of progressive bile duct loss in primary biliary cirrhosis remains unclear. In this study, the involvement of cellular senescence of biliary epithelial cells was examined in liver tissue samples from patients with primary biliary cirrhosis (n = 33), and compared with control diseased and normal livers (n = 83). In addition, cellular senescence was induced by oxidative stress in cultured mouse biliary epithelial cells. Biliary epithelial cells in small bile ducts in primary biliary cirrhosis, especially those in patients presenting with chronic non-suppurative cholangitis, frequently expressed senescence-associated beta-galactosidase, and senescence-associated p16(INK4) and p21(WAF1/CIP). In contrast, senescence-associated markers were rarely expressed in small bile ducts in control livers. The infiltration of myeloperoxidase-positive inflammatory cells into biliary epithelial cell layers was closely associated with the cellular senescence of biliary epithelial cells in early-stage PBC. Cellular senescence of cultured mouse biliary epithelial cells was induced by treatment with H2O2 via the p38MAPK-dependent pathway and nitric oxide-augmented H2O2-induced cellular senescence. Oxidative stress- and nitric oxide-mediated cellular senescence may be involved in bile duct lesions, which are followed by progressive bile duct loss in primary biliary cirrhosis.     

Exogenous antigens are processed through the endoplasmic reticulum-associated degradation (ERAD) in cross-presentation by dendritic cells

Antigen cross-presentation is critical in infectious and tumor immunity where cytotoxic T lymphocytes are induced by dendritic cells specifically equipped with cellular machineries to present exogenous antigens with major histocompatibility complex (MHC) class I molecules. To examine molecular mechanisms of antigen cross-presentation, we employed as a model system a murine dendritic cell line DC2.4 capable of presenting soluble antigens such as ovalbumin (OVA) with MHC class I. Here, we demonstrate that exogenously added OVA is accumulated in the endoplasmic reticulum (ER) and late endosomes followed by retrograde transport to the cytoplasm through the Sec61 transporter complexes, and that CHIP functions as an E3 ubiquitin-ligase for OVA degradation by proteasomes. This mechanism is essentially the same as that known as the ER-associated degradation (ERAD) in the quality control of secretary and membrane proteins.     

Hypoxia-induced renal epithelial cell death through caspase-dependent pathway: role of Bcl-2, Bcl-xL and Bax in tubular injury

Although injury of epithelial cells has been reported to be responsible for renal disease such as acute renal failure, its molecular mechanisms are largely unknown. As hypoxia has been postulated as the initial trigger of epithelial injury, we studied the molecular mechanisms of apoptosis induced by hypoxia in human renal epithelial cells. Severe hypoxia caused epithelial cell death, accompanied by a significant increase in LDH release (p<0.01). In addition, hypoxic treatment of epithelial cells resulted in a significant increase in apoptotic cells as assessed by cell morphology (p<0.01). The apoptotic change in epithelial cells under hypoxic condition was also confirmed by a significant increase in caspase-3-like activity and release of cytochrome c (p<0.01). The decrease in epithelial cell number was completely abolished by addition of a wide-spectrum caspase inhibitor, Z-VAD, rather than Z-DEVD, a specific caspase-3 inhibitor (p<0.01). Thus, we further studied the molecular mechanisms of apoptosis induced by hypoxia. Anti-apoptotic factors, Bcl-2 and Bcl-xL, were significantly decreased in epithelial cells under a hypoxic condition as assessed by Western blotting (p<0.01). In contrast, hypoxia did not alter their location. Of particular importance, translocation of a proapoptotic factor, Bax, from the cytoplasm to the mitochondrial membrane was observed in response to hypoxia, whereas total Bax protein was not changed by hypoxia. Overall, this study demonstrated that hypoxia caused epithelial cell death induced by caspase-3-like activity-dependent apoptosis. The pro-apoptotic mechanisms of hypoxia in epithelial cells largely depend on a significant decrease in Bcl-2 and Bcl-xL. In addition, the present results demonstrate that translocation of Bax from the cytosol to the mitochondrial membrane occurred under hypoxia, thereby leading to pathological tissue destruction.     

Identification of ligand recognition sites in heat-stable enterotoxin receptor, membrane-associated guanylyl cyclase C by site-directed mutational analysis.

Guanylyl cyclase C (STaR), a receptor protein for heat-stable enterotoxin (STa) elaborated by Escherichia coli, is associated with and spans the plasma membrane of mammalian intestinal cells. The extracellular domain functions in the binding of STa and the association of each domain to an oligomeric form. Two amino acid residues, Arg-136 and Asp-347, were identified as the residues binding to STa in the extracellular domain of pig STaR by site-directed mutagenesis and analysis of expression on 293T cells. Replacement of these residues by other amino acid residues resulted in the loss of binding of pig STaR to STa, and as a result, STa-induced guanylyl cyclase activity was eliminated. Furthermore, mutation in a region (from Asp-347 to Val-401) which is close to the transmembrane domain caused a significant reduction in both STa-binding activity and guanylyl cyclase catalytic activity. These results suggest that the region adjacent to the transmembrane domain plays an important role in facilitating a favorable conformation of STaR for STa binding.     

Overexpression of the myc target gene Mina53 in advanced renal cell carcinoma

The myc target gene Mina53 was reported to be overexpressed in esophageal cancer with a poor prognosis. The purpose of the present study was to examined Mina53 expression and its relationship to clinicopathological parameters in human renal cell carcinoma (RCC). Mina53 and Ki-67 expression was examined on immunohistochemistry for 64 surgically resected RCC and non-cancerous tissue. In addition, the relationship between Mina53 expression and clinicopathological prognostic factors of RCC such as age, stage, microvenous invasion (MVI), histological subtype, Ki-67 labeling index (LI), and prognosis, was examined. Mina53 was expressed in the nuclei of tumor cells and tubular nuclei of normal renal tissue. The expression level of Mina53 was significantly higher in patients with poor prognostic factors (stage IV, MVI-positive, and sarcomatoid RCC, and high Ki-67 LI). The prognosis of high Mina53-expressing tumors was significantly poorer than that of non-Mina53-high tumors (P < 0.0001). In conclusion, Mina53 is overexpressed in RCC tissue from patients with poor prognostic factors, suggesting that Mina53 overexpression is one of the factors for poor prognosis in RCC.     

Comparative immune responses of patients with chronic pulmonary diseases during the 2-year period after pneumococcal vaccination

Antibody responses to a 23-valent pneumococcal vaccine for Streptococcus pneumoniae serotypes 6B, 14, 19F, and 23F in 84 patients with chronic pulmonary diseases over a 2-year period after vaccination were examined by using a third-generation enzyme-linked immunosorbent assay. Of these patients, 28 (31%) were low responders who had developed increases of at least twofold in the levels of serotype-specific immunoglobulin G (IgG) in sera for none of the four serotypes at 1 month after vaccination. Although no specific clinical features of low responders were evident, their prevaccination levels of IgG for all serotypes were higher than those of responders. In responders, the levels of IgG specific for serotypes 14 and 23F in sera were greatly increased 1 month after vaccination and those specific for serotypes 6B and 19F were moderately increased. In contrast, no significant increases in the levels of IgG specific for serotypes 6B, 19F, and 23F in the low responders during the same period were found, but the levels of IgG specific for serotype 14 did increase. Although a rapid decline in the levels of IgG for all serotypes in responders between 1 month and 6 months after vaccination was found, the levels of IgG specific for serotypes 14 and 23F in sera remained higher than the prevaccination levels for at least 2 years after vaccination. These data suggest the need for the revaccination of responders but not low responders among patients with chronic pulmonary diseases. Revaccination as early as 3 years postvaccination is recommended for responders to increase the reduced levels of IgG in sera, especially those specific for the weak vaccine antigens.