Obeticholic acid protects against hepatocyte death and liver fibrosis in a murine model of nonalcoholic steatohepatitis.

Accumulating evidence has suggested that farnesoid X receptor (FXR) agonists, such as obeticholic acid (OCA) are therapeutically useful for non-alcoholic steatohepatitis (NASH). However, it is still unclear how FXR agonists protect against NASH and which cell type is the main target of FXR agonists. In this study, we examined the effects of OCA on the development of NASH using melanocortin 4 receptor-deficient (MC4R-KO) mice that progressively developed hepatic steatosis and NASH on Western diet (WD). Treatment with OCA effectively prevented chronic inflammation and liver fibrosis in WD-fed MC4R-KO mice with only marginal effect on body weight and hepatic steatosis. Hepatic crown-like structure (hCLS) is a unique histological structure characteristic of NASH, which triggers hepatocyte death-induced interstitial fibrosis. Intriguingly, treatment with OCA markedly reduced hCLS formation even after MC4R-KO mice developed NASH, thereby inhibiting the progression of liver fibrosis. As its mechanism of action, OCA suppressed metabolic stress-induced p53 activation and cell death in hepatocytes. Our findings in this study highlight the role of FXR in hepatocytes in the pathogenesis of NASH. Collectively, this study demonstrates the anti-fibrotic effect of OCA in a murine model of NASH with obesity and insulin resistance, which suggests the clinical implication for human NASH.

CD11c+ resident macrophages drive hepatocyte death-triggered liver fibrosis in a murine model of nonalcoholic steatohepatitis.

Although recent evidence has pointed to the role of organ- and pathogenesis-specific macrophage subsets, it is still unclear which subsets are critically involved in the pathogenesis of nonalcoholic steatohepatitis (NASH). Using melanocortin-4 receptor-deficient (MC4R-KO) mice fed Western diet (WD), which exhibit liver phenotypes similar to those of human NASH, we found a histological structure, termed hepatic crown-like structure (hCLS), in which CD11c+ macrophages surround dead/dying hepatocytes, a prominent feature of NASH. Here, we demonstrate that hCLS-constituting macrophages could be a novel macrophage subset that drives hepatocyte death-triggered liver fibrosis. In an "inducible NASH model," hepatocyte death induces hCLS formation and liver fibrosis sequentially in the short term. In combination with the long-term WD feeding model, we also showed that resident macrophages are a major cellular source of CD11c+ macrophages constituting hCLS, which exhibited gene expression profiles distinct from CD11c- macrophages scattered in the liver. Moreover, depletion of CD11c+ macrophages abolished hCLS formation and fibrogenesis in NASH. Our clinical data suggest the role of CD11c+ macrophages in the disease progression from simple steatosis to NASH. This study sheds light on the role of resident macrophages, in addition to recruited macrophages, in the pathogenesis of NASH.

Suppression of adenylyl cyclase-mediated cAMP production by plasma membrane associated cytoskeletal protein 4.1G.

It has been shown lately that activity of G protein-coupled receptors (GPCRs) is regulated by an array of proteins binding to carboxy (C)-terminus of GPCRs. Proteins of 4.1 family are subsets of subcortical cytoskeletal proteins and are known to stabilize cellular structures and proteins at the plasma membrane. One of the 4.1 family proteins, 4.1G has been shown to interact with the C-terminus of GPCRs and regulate intracellular distribution of the receptors, including parathyroid hormone (PTH)/PTH-related protein receptor (PTHR). PTHR is coupled to trimeric G proteins G(s) and G(q), which activate the adenylyl cyclase/cyclic AMP (cAMP) pathway and phospholipase C pathway, respectively. During the course of investigation of the role of 4.1G on adenylyl cyclase/cAMP signaling pathway, we found that 4.1G suppressed forskolin-induced cAMP production in cells. The cAMP accumulation induced by forskolin was decreased in HEK293 cells overexpressing 4.1G or increased in 4.1G-knockdown cells. Furthermore, PTH -(1-34)-stimulated cAMP production was also suppressed in the presence of exogenously expressed 4.1G despite its activity to increase the distribution of PTHR to the cell surface. In cells overexpressing FERM domain-deleted 4.1G, a mutant form of the protein deficient in plasma membrane distribution, neither forskolin-induced nor PTH -(1-34)-stimulated cAMP production was not altered. The suppression of the forskolin-induced cAMP production was observed even in membrane preparations of 4.1G-overexpressing cells. In 4.1G-knockdown HEK293 cells, plasma membrane distribution of adenylyl cyclase 6, one of the major subtypes of the enzyme in the cells, showed a slight decrease, in spite of the increased production of cAMP in those cells when stimulated by forskolin. Also, cytochalasin D treatment did not cause any influence on forskolin-induced cAMP production in HEK293 cells. These data indicate that plasma membrane-associated 4.1G regulates GPCR-mediated G(s) signaling by suppressing adenylyl cyclase-mediated cAMP production.

[A case of small cell carcinoma of the esophagus with remarkable response to chemotherapy with CPT-11 and CDDP].

A 63-year-old man visited our hospital with complaints of the chest pain and loss of appetite. A computed tomography of chest showed wall thickening in the lower portion of the esophagus and carinal and para-aorta lymph node swelling. Upper gastrointestinal endoscopy revealed an irregular ulcerated lesion in the middle portion of the esophagus, which was pathologically diagnosed as small cell carcinoma. A computed tomography of the abdomen showed multiple liver metastases and para-aortic, cardiac, and common hepatic arterial lymph node swelling. One course of combined chemotherapy with CPT-11 and CDDP, then 3 courses of chemotherapy with CPT-11 showed clinical complete remission.

Serum reactivity against bacterial pyruvate dehydrogenase: increasing the specificity of anti-mitochondrial antibodies for the diagnosis of primary biliary cirrhosis.

Antimitochondrial antibodies (AMA) are the serum hallmark of primary biliary cirrhosis (PBC). However, AMA-positivity can be found in non-PBC sera when lower dilutions are used, thus raising issues about the specificity and sensitivity of the test. AMA reacts primarily with the lipoylated domains of pyruvate dehydrogenase-E2 (PDC-E2) which is highly conserved across species, including bacteria. We studied 77 serum samples, including 24 from patients with anti-PDC-E2-positive PBC and 53 controls (16 with autoimmune hepatitis (AIH), 10 with primary sclerosing cholangitis (PSC), and 27 healthy individuals) for their reactivities at serial dilutions (1:10, 1:20 and 1:40) against Escherichia coli DH5 alpha lysate overexpressing human PDC-E2 using immunoblotting (IB). A murine anti-human PDC-E2 monoclonal antibody (mAB) was used as control. We further studied positive sera using adsorption with a synthetic E. coli peptide sharing similarity with human PDC-E2. Finally, we verified whether a unique buffer for E. coli preparation could reduce non-specific serum reactivity. Results demonstrated that 100% of anti-PDC-E2-positive PBC and up to 38% of control sera at 1:10 dilution recognized E. coli PDC-E2 at IB while dilution tests indicated that the overall potency of PBC reactivity was 100-fold higher compared to controls. In fact, a subgroup (20-38%) of non-PBC sera were positive at low titers but lost the reactivity when absorbed with the synthetic E. coli peptide. Finally, our unique buffer reduced the reactivity of non-PBC sera as measured by ELISA. In conclusion, we demonstrated that weak cross-reactivity with E. coli PDC-E2 occurs in non-PBC sera at lower dilutions and that such reactivity is not due to AMA-positivity. The use of a specific buffer might avoid the risk of false positive AMA determinations when E. coli-expressed recombinant antigens are used.

One-step preparation of chitosan-coated cationic liposomes by an improved supercritical reverse-phase evaporation method.

High-pressure carbon dioxide in contact with water dissolves to form carbonic acid, causing a decrease in pH. By use of these characteristics of a CO2/H2O biphasic system, chitosan-coated cationic liposomes of l-alpha-dipalmitoylphosphatidylcholine were successfully prepared by an improved supercritical reverse-phase evaporation (ISCRPE) method. Liposome-chitosan complexes carrying a positive charge were prepared in a single-step procedure without the use of acid or organic solvent, including ethanol. The maximum trapping efficiency of liposomes prepared by the ISCRPE method was 17%, with or without the addition of chitosan, compared to only 2% for liposomes prepared by the Bangham method. Furthermore, the liposomal dispersion was stable at room temperature in a sealed tube for over 30 days.

Preparation of liposomes using an improved supercritical reverse phase evaporation method.

Liposomes of various phospholipids were prepared using an improved supercritical reverse phase evaporation (ISCRPE) method that utilizes supercritical carbon dioxide (scCO(2)) as an alternative to organic solvents. Using this method, in the absence of any organic solvent including ethanol, the maximum trapping efficiency of glucose reached 36% for 20 mM l-alpha-dioleoylphosphatidylcholine (DOPC), compared to less than 10% using the Bangham method. Liposomes prepared by the ISCRPE method were highly stable for one month at room temperature. Freeze fractured TEM observations, osmotic shrinkage measurements, and DSC measurements revealed that the liposomes prepared by the ISCRPE method are unilamellar vesicles with loosely packed phospholipids. Comparison of nitrogen with scCO(2) revealed that the presence of CO(2) is necessary for the formation of liposomes.

Long-term results of percutaneous balloon dilation for ureterointestinal anastomotic strictures.

BACKGROUND: We determined the long-term result of our percutaneous antegrade balloon dilation technique performed for adult patients with ureterointestinal anastomotic stricture between 1992 and 1997. METHODS: Balloon dilation was performed on 13 ureterointestinal anastomotic structures in 10 patients. After a nephrostomy was performed, a guide wire was introduced into the intestinal loop through the stenotic portion under direct observation using a ureterorenoscope. Dilation was performed using the Olbert balloon dilator (30-Fr) inserted along a guide wire into the stenotic portion. A 20-Fr or 22-Fr multihole catheter was left for approximately 6 weeks. No major complications were encountered during or after these procedures. After removal of the indwelling catheters, the progress of each patient was followed fo rat least 14 months. RESULTS: Additional dilation was necessary in three of 10 patients for the recurrent stricture. The balloon dilation was ineffective in two patients with a long stenosis of the ureter or a previous history of radiation therapy for uterine cancer. Eight of 10 patients showed satisfactory outcomes during the mean follow-up period of 47.1 months. CONCLUSIONS: Based on these results, we believe that the balloon dilation could be the first line of treatment for strictures of uro-digestive anastomosis, except for some patients with a long stenosis or a previous history of intrapelvic radiation.

Activities of beta-lactams, fluoroquinolones, amikacin and fosfomycin alone and in combination against Pseudomonas aeruginosa isolated from complicated urinary tract infections.

Using the checkerboard titration method as well as the time-kill curve technique, we investigated the activities of beta-lactams, fluoroquinolones, amikacin, and fosfomycin alone and in combination against Pseudomonas aeruginosa isolated from patients with complicated urinary tract infections. In the checkerboard titration studies, none of 21 combinations demonstrated antagonism against 26 strains tested, and the mean fractional inhibitory concentration (FIC) indices for these combinations ranged between 0.4694 and 0.9828. Corresponding to the respective FIC indices, the bactericidal activity determined in combinations of meropenem with ciprofloxacin or amikacin and ceftazidime with ciprofloxacin at sub-minimum inhibitory concentrations (MICs) produced a great reduction in bacterial counts (>/=2 log10 CFU/ml) within 6 h of administration against most of the strains, including strains resistant to one or both drugs, and these synergistic effects were confirmed morphologically by scanning electron microscopy. In time-lag combinations, the first administration of ciprofloxacin or amikacin supplemented by meropenem with 1-h lag diminished bactericidal activity, in comparison with the simultaneous administration of the drugs. These results suggest that simultaneous combinations of beta-lactams with fluoroquinolones or amikacin may be useful alternatives for the treatment of serious infections due to P. aeruginosa.