Endoscopic Submucosal Dissection for Early Esophageal Adenocarcinoma: Low Rates of Metastases in Mucosal Cancers with Poor Differentiation.

BACKGROUND AND AIMS: Endoscopic resection (ER) is accepted as standard treatment for intramucosal esophageal adenocarcinoma (EAC) with well or moderate differentiation. Poor differentiation (PD) is judged as a risk factor for lymph node metastasis (LNM) and surgery is recommended. However, the evidence for this recommendation is weak. Study aim was to analyze the clinical course of patients after ER of EAC with PD. PATIENTS AND METHODS: Patients undergoing endoscopic submucosal dissection for EAC were included from 16 German centers. Inclusion criteria were PD in the resection specimen, R0 resection and endoscopic follow-up. Primary outcome was the metastasis rate during follow-up. Analysis was performed retrospectively in a prospectively collected database. RESULTS: 25 patients with PD as single risk factor (group A) and 15 patients with PD and additional risk factors (submucosal invasion and/or lymphovascular invasion) were included. The metastasis rate was was 1/25 (4.0%; 95%CI 0.4-17.2) in group A and 3/15 (20.0%; 95%CI 6.0-44.4%) in group B, respectively (p=0.293). The rate of EAC-associated deaths was 1/25 (4%; 95%CI 0.4-17.2%) versus 3/15 (20%; 95%CI 6.0-44.4%) in group B (p=0.293) while the overall death rate was 7/25 (28.0%; 95%CI 13.5-47.3%) versus 3/15 (20%; 95%CI 6.0-44.4%) (p=0.715). Median follow-up was 30 months (IQR 15-53). CONCLUSIONS: During long-term follow-up the risk of metastasis is low after ER of mucosal EAC with PD as single risk factor. A conservative approach seems justified in this small patient group. However, the treatment strategy has to be determined on an individualized basis until further prospective data are available.

Free fatty acids shift insulin-induced hepatocyte proliferation towards CD95-dependent apoptosis.

Insulin is known to induce hepatocyte swelling, which triggers via integrins and c-Src kinase an activation of the epidermal growth factor receptor (EGFR) and subsequent cell proliferation (1). Free fatty acids (FFAs) are known to induce lipoapoptosis in liver cells in a c-Jun-NH2-terminal kinase (JNK)-dependent, but death receptor-independent way (2). As non-alcoholic steatohepatitis (NASH) is associated with hyperinsulinemia and increased FFA-blood levels, the interplay between insulin and FFA was studied with regard to hepatocyte proliferation and apoptosis in isolated rat and mouse hepatocytes. Saturated long chain FFAs induced apoptosis and JNK activation in primary rat hepatocytes, but did not activate the CD95 (Fas, APO-1) system, whereas insulin triggered EGFR activation and hepatocyte proliferation. Coadministration of insulin and FFAs, however, abolished hepatocyte proliferation and triggered CD95-dependent apoptosis due to a JNK-dependent association of the activated EGFR with CD95, subsequent CD95 tyrosine phosphorylation and formation of the death-inducing signaling complex (DISC). JNK inhibition restored the proliferative insulin effect in presence of FFAs and prevented EGFR/CD95 association, CD95 tyrosine phosphorylation and DISC formation. Likewise, in presence of FFAs insulin increased apoptosis in hepatocytes from wild type but not from Alb-Cre-FAS(fl/fl) mice, which lack functional CD95. It is concluded that FFAs can shift insulin-induced hepatocyte proliferation toward hepatocyte apoptosis by triggering a JNK signal, which allows activated EGFR to associate with CD95 and to trigger CD95-dependent apoptosis. Such phenomena may contribute to the pathogenesis of NASH.

Tauroursodeoxycholate Protects Rat Hepatocytes from Bile Acid-Induced Apoptosis via ß1-Integrin- and Protein Kinase A-Dependent Mechanisms.

BACKGROUND/AIMS: Ursodeoxycholic acid, which in vivo is rapidly converted into its taurine conjugate, is frequently used for the treatment of cholestatic liver disease. Apart from its choleretic effects, tauroursodeoxycholate (TUDC) can protect hepatocytes from bile acid-induced apoptosis, but the mechanisms underlying its anti-apoptotic effects are poorly understood. METHODS: These mechanisms were investigated in perfused rat liver and isolated rat hepatocytes. RESULTS: It was found that TUDC inhibited the glycochenodeoxycholate (GCDC)-induced activation of the CD95 death receptor at the level of association between CD95 and the epidermal growth factor receptor. This was due to a rapid TUDC-induced ß1-integrin-dependent cyclic AMP (cAMP) signal with induction of the dual specificity mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1), which prevented GCDC-induced phosphorylation of mitogen-activated protein kinase kinase 4 (MKK4) and c-jun-NH2-terminal kinase (JNK) activation. Furthermore, TUDC induced a protein kinase A (PKA)-mediated serine/threonine phosphorylation of the CD95, which was recently identified as an internalization signal for CD95. Furthermore, TUDC inhibited GCDC-induced CD95 targeting to the plasma membrane in a ß1-integrin-and PKA-dependent manner. In line with this, the ß1-integrin siRNA knockdown in sodium taurocholate cotransporting polypeptide (Ntcp)-transfected HepG2 cells abolished the protective effect of TUDC against GCDC-induced apoptosis. CONCLUSION: TUDC exerts its anti-apoptotic effect via a ß1-integrin-mediated formation of cAMP, which prevents CD95 activation by hydrophobic bile acids at the levels of JNK activation and CD95 serine/threonine phosphorylation.

α5 ß1-integrins are sensors for tauroursodeoxycholic acid in hepatocytes.

UNLABELLED: Ursodeoxycholic acid, which in vivo is converted to its taurine conjugate tauroursodeoxycholic acid (TUDC), is a mainstay for the treatment of cholestatic liver disease. Earlier work showed that TUDC exerts its choleretic properties in the perfused rat liver in an α5 ß1 integrin-mediated way. However, the molecular basis of TUDC-sensing in the liver is unknown. We herein show that TUDC (20 µmol/L) induces in perfused rat liver and human HepG2 cells the rapid appearance of the active conformation of the ß1 subunit of α5 ß1 integrins, followed by an activating phosphorylation of extracellular signal-regulated kinases. TUDC-induced kinase activation was no longer observed after ß1 integrin knockdown in isolated rat hepatocytes or in the presence of an integrin-antagonistic hexapeptide in perfused rat liver. TUDC-induced ß1 integrin activation occurred predominantly inside the hepatocyte and required TUDC uptake by way of the Na(+) /taurocholate cotransporting peptide. Molecular dynamics simulations of a 3D model of α5 ß1 integrin with TUDC bound revealed significant conformational changes within the head region that have been linked to integrin activation before. CONCLUSIONS: TUDC can directly activate intrahepatocytic ß1 integrins, which trigger signal transduction pathways toward choleresis. (HEPATOLOGY 2013).

HbG200-mediated preinduction of heme oxygenase-1 improves bile flow and ameliorates pericentral downregulation of Bsep and Mrp2 following experimental liver ischemia and reperfusion.

We studied the downregulation of hepatobiliary transport systems and the effect of pharmacological heme oxygenase-1 (HO-1) preinduction by Hemoglobin-Glutamer 200 (HbG200) in cold ischemia-reperfused rat liver (I/R). Cold I/R reduced bile flow in the reperfusion period from 3.10±0.10 ml/3 h to 0.54±0.20 ml/3 h (p<0.05) and biliary taurocholate excretion from 45.9±13.81 µmol/3 h to 1.87±0.46 µmol/3 h (p<0.05). Mrp2, Bsep and Ntcp peak immunofluorescence in pericentral hepatocytes decreased to 79.0±2.6% (p<0.001), 80.6±8.4% (p<0.05) and 65.8±5.0% (p<0.01), respectively. Pre-induction of HO-1 by HbG200 was largely confined to pericentral hepatocytes. HO-1 induction attenuated the decreased bile flow (0.91±0.16 ml/3 h, p<0.05) and canalicular taurocholate secretion (4.33±1.71 µmol/3 h, p<0.05). Bsep and Mrp2 peak immunofluorescence in pericentral hepatocytes was largely restored. Activation of JNK and Fyn by cold I/R was significantly attenuated by HO-1. Inhibiting HO activity by tin protoporphyrin IX after HbG200 administration reversed the effect on bile flow and canalicular transporter expression. In conclusion, pericentral downregulation of Bsep and Mrp2 following cold I/R is ameliorated by inducing HO-1 and was associated with diminished hepatocellular JNK and Fyn signaling. HO-1 may serve as a therapeutic target to attenuate hepatocellular cholestasis following I/R injury.

The Src family kinase Fyn mediates hyperosmolarity-induced Mrp2 and Bsep retrieval from canalicular membrane.

In perfused rat liver, hyperosmolarity induces Mrp2- (Kubitz, R., D'urso, D., Keppler, D., and Häussinger, D. (1997) Gastroenterology 113, 1438-1442) and Bsep retrieval (Schmitt, M., Kubitz, R., Lizun, S., Wettstein, M., and Häussinger, D. (2001) Hepatology 33, 509-518) from the canalicular membrane leading to cholestasis. The aim of this study was to elucidate the underlying signaling events. Hyperosmolarity-induced retrieval of Mrp2 and Bsep from the canalicular membrane in perfused rat liver was accompanied by an activating phosphorylation of the Src kinases Fyn and Yes but not of c-Src. Both hyperosmotic transporter retrieval and Src kinase activation were sensitive to apocynin (300 µmol/liter), N-acetylcysteine (NAC; 10 mmol/liter), and SU6656 (1 µmol/liter). Also PP-2 (250 nmol/liter), which inhibited hyperosmotic Fyn but not Yes activation, prevented hyperosmotic transporter retrieval from the canalicular membrane, suggesting that Fyn but not Yes mediates hyperosmotic Bsep and Mrp2 retrieval. Neither hyperosmotic Fyn activation nor Bsep/Mrp2 retrieval was observed in livers from p47(phox) knock-out mice. Hyperosmotic activation of JNKs was sensitive to apocynin and NAC but insensitive to SU6656 and PP-2, indicating that JNKs are not involved in transporter retrieval, as also evidenced by experiments using the JNK inhibitors L-JNKI-1 and SP6001255, respectively. Hyperosmotic transporter retrieval was accompanied by a NAC and Fyn knockdown-sensitive inhibition of biliary excretion of the glutathione conjugate of 1-chloro-2,4-dinitrobenzene in perfused rat liver and of cholyl-L-lysyl-fluorescein secretion into the pseudocanaliculi formed by hepatocyte couplets. Hyperosmolarity triggered an association between Fyn and cortactin and increased the amount of phosphorylated cortactin underneath the canalicular membrane. It is concluded that the hyperosmotic cholestasis is triggered by a NADPH oxidase-driven reactive oxygen species formation that mediates Fyn-dependent retrieval of the Mrp2 and Bsep from the canalicular membrane, which may involve an increased cortactin phosphorylation.

CD95 death receptor and epidermal growth factor receptor (EGFR) in liver cell apoptosis and regeneration.

Recent evidence suggests that signaling pathways towards cell proliferation and cell death are much more interconnected than previously thought. Whereas not only death receptors such as CD95 (Fas, APO-1) can couple to both, cell death and proliferation, also growth factor receptors such as the epidermal growth factor receptor (EGFR) are involved in these opposing kinds of cell fate. EGFR is briefly discussed as a growth factor receptor involved in liver cell proliferation during liver regeneration. Then the role of EGFR in activating CD95 death receptor in liver parenchymal cells (PC) and hepatic stellate cells (HSC), which represent a liver stem/progenitor cell compartment, is described summarizing different ways of CD95- and EGFR-dependent signaling in the liver. Here, depending on the hepatic cell type (PC vs. HSC) and the respective signaling context (sustained vs. transient JNK activation) CD95-/EGFR-mediated signaling ends up in either liver cell apoptosis or cell proliferation.

Insulin induces swelling-dependent activation of the epidermal growth factor receptor in rat liver.

The aim of the study was to analyze whether the proliferative effects of insulin in rat liver involve cross-signaling toward the epidermal growth factor receptor (EGFR) and whether this is mediated by insulin-induced hepatocyte swelling. Studies were performed in the perfused rat liver and in primary rat hepatocytes. Insulin (35 nmol/liter) induced phosphorylation of the EGFR at position Tyr(845) and Tyr(1173), but not at Tyr(1045), suggesting that EGF is not involved in insulin-induced EGFR activation. Insulin-induced EGFR phosphorylation and subsequent ERK1/2 phosphorylation were sensitive to bumetanide, indicating an involvement of insulin-induced hepatocyte swelling. In line with this, hypoosmotic (225 mosmol/liter) hepatocyte swelling also induced EGFR and ERK1/2 activation. Insulin- and hypoosmolarity-induced EGFR activation were sensitive to inhibition by an integrin-antagonistic RGD peptide, an integrin beta1 subtype-blocking antibody, and the c-Src inhibitor PP-2, indicating the involvement of the recently described integrin-dependent osmosensing/signaling pathway (Schliess, F., Reissmann, R., Reinehr, R., vom Dahl, S., and Häussinger, D. (2004) J. Biol. Chem. 279, 21294-21301). As shown by immunoprecipitation studies, insulin and hypoosmolarity induced a rapid, RGD peptide-, integrin beta1-blocking antibody and PP-2-sensitive association of c-Src with the EGFR. As for control, insulin-induced insulin receptor substrate-1 phosphorylation remained unaffected by the RGD peptide, PP-2, or inhibition of the EGFR tyrosine kinase activity by AG1478. Both insulin and hypoosmolarity induced a significant increase in BrdU uptake in primary rat hepatocytes, which was sensitive to RGD peptide-, integrin beta1-blocking antibody, PP-2, AG1478, and PD098059. It is concluded that insulin- or hypoosmolarity-induced hepatocyte swelling triggers an integrin- and c-Src kinase-dependent EGFR activation, which may explain the proliferative effects of insulin.

Activation of integrins by urea in perfused rat liver.

High concentrations of urea were shown to induce a paradoxical regulatory volume decrease response with K(+) channel opening and subsequent hepatocyte shrinkage (Hallbrucker, C., vom Dahl, S., Ritter, M., Lang, F., and Häussinger, D. (1994) Pflügers Arch. 428, 552-560), although the hepatocyte plasma membrane is thought to be freely permeable to urea. The underlying mechanisms remained unclear. As shown in the present study, urea (100 mmol/liter) induced within 1 min an activation of ß(1) integrins followed by an activation of focal adhesion kinase, c-Src, p38(MAPK), extracellular signal-regulated kinases, and c-Jun N-terminal kinase. Because α(5)ß(1) integrin is known to act as a volume/osmosensor in hepatocytes, which becomes activated in response to hepatocyte swelling, the findings suggest that urea at high concentrations induces a nonosmotic activating perturbation of this osmosensor, thereby triggering a volume regulatory K(+) efflux. In line with this, similar to hypo-osmotic hepatocyte swelling, urea induced an inhibition of hepatic proteolysis, which was sensitive to p38(MAPK) inhibition. Molecular dynamics simulations of a three-dimensional model of the ectodomain of α(5)ß(1) integrin in water, urea, or thiourea solutions revealed significant conformational changes of α(5)ß(1) integrin in urea and thiourea solutions, in contrast to the simulation of α(5)ß(1) in water. These changes lead to an unbending of the integrin structure around the genu, which may suggest activation, whereas the structures of single domains remained essentially unchanged. It is concluded that urea at high concentrations affects hepatic metabolism through direct activation of the α(5)ß(1) integrin system.

Osmotic regulation of bile acid transport, apoptosis and proliferation in rat liver.

Changes in mammalian cell volume as induced by either anisoosmolarity, hormones, nutrients or oxidative stress critically contribute to the regulation of metabolism, membrane transport, gene expression and the susceptibility to cellular stress. Osmosensing, i.e. the registration of cell volume changes, triggers signal transduction pathways towards effector pathways (osmosignaling) which link alterations of cell volume to changes in cell function. This review summarizes our own work on the understanding of how osmosensing and osmosignaling integrate into the overall context of bile acid transport, growth factor signaling and the execution of apoptotic programs.

BCL-2 family inhibitors enhance histone deacetylase inhibitor and sorafenib lethality via autophagy and overcome blockade of the extrinsic pathway to facilitate killing.

We examined whether the multikinase inhibitor sorafenib and histone deacetylase inhibitors (HDACI) interact to kill pancreatic carcinoma cells and determined the impact of inhibiting BCL-2 family function on sorafenib and HDACI lethality. The lethality of sorafenib was enhanced in pancreatic tumor cells in a synergistic fashion by pharmacologically achievable concentrations of the HDACIs vorinostat or sodium valproate. Overexpression of cellular FLICE-like inhibitory protein (c-FLIP-s) or knockdown of CD95 suppressed the lethality of the sorafenib/HDACI combination (sorafenib + HDACI). In immunohistochemical analyses or using expression of fluorescence-tagged proteins, treatment with sorafenib and vorinostat together (sorafenib + vorinostat) promoted colocalization of CD95 with caspase 8 and CD95 association with the endoplasmic reticulum markers calnexin, ATG5, and Grp78/BiP. In cells lacking CD95 expression or in cells expressing c-FLIP-s, the lethality of sorafenib + HDACI exposure was abolished and was restored when cells were coexposed to BCL-2 family inhibitors [ethyl [2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)]-4H-chromene-3-carboxylate (HA14-1), obatoclax (GX15-070)]. Knockdown of BCL-2, BCL-XL, and MCL-1 recapitulated the effects of GX15-070 treatment. Knockdown of BAX and BAK modestly reduced sorafenib + HDACI lethality but abolished the effects of GX15-070 treatment. Sorafenib + HDACI exposure generated a CD95- and Beclin1-dependent protective form of autophagy, whereas GX15-070 treatment generated a Beclin1-dependent toxic form of autophagy. The potentiation of sorafenib + HDACI killing by GX15-070 was suppressed by knockdown of Beclin1 or of BAX + BAK. Our data demonstrate that pancreatic tumor cells are susceptible to sorafenib + HDACI lethality and that in tumor cells unable to signal death from CD95, use of a BCL-2 family antagonist facilitates sorafenib + HDACI killing via autophagy and the intrinsic pathway.

CD95 ligand is a proliferative and antiapoptotic signal in quiescent hepatic stellate cells.

BACKGROUND & AIMS: Despite expression of CD95 (Fas) receptor, hepatic stellate cells (HSCs) are fairly resistant toward CD95 ligand (CD95L)-induced cell death. The underlying mechanisms and the function of the CD95 system in quiescent HSCs, however, are unknown. METHODS: The effects of CD95L on quiescent, 1- to 2-day cultured rat HSCs were studied with regard to CD95 activation, signal transduction, proliferation, and apoptosis. RESULTS: In quiescent HSCs, CD95L led to a rapid phosphorylation of the epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (Erk), and c-Src, but not of c-Jun-N-terminal kinase and p47(phox), an activating subunit of reduced nicotinamide adenine dinucleotide phosphate oxidase. CD95L-induced EGFR and Erk phosphorylation were abolished after proteinase inhibition by GM6001 and in the presence of neutralizing epidermal growth factor antibodies, suggestive of a ligand-dependent EGFR phosphorylation in response to CD95L. In quiescent HSCs, CD95L did not induce apoptotic cell death but stimulated HSC proliferation and triggered a rapid inactivating CD95 tyrosine nitration that was not detected in activated HSCs (10-14 days of culture). EGFR phosphorylation, HSC proliferation, and CD95 tyrosine nitration were also triggered by tumor necrosis factor alpha and tumor necrosis factor-related apoptosis-inducing ligand. CONCLUSIONS: In quiescent HSCs, CD95L and other death receptor ligands are mitogens through a ligand-dependent EGFR phosphorylation. Simultaneously, an antiapoptotic signaling is triggered by CD95L-induced CD95 tyrosine nitration. This unusual response to death receptor ligands may help quiescent HSCs to participate in liver regeneration following liver injury.

Epidermal growth factor receptor signaling in liver cell proliferation and apoptosis.

Recent evidence suggests that epidermal growth factor receptor (EGFR)-dependent signaling contributes to liver cell proliferation, as well as to apoptotic liver cell death, and represents an important regulator of hepatic regeneration. This article summarizes recent findings on the molecular mechanisms involved in EGFR-mediated cell proliferation and apoptosis. The emphasis is on the interplay between EGFR and CD95 (Fas, APO-1) death receptor-signaling, which is determined by the signaling context and liver cell type investigated.

Selenoprotein P expression is controlled through interaction of the coactivator PGC-1alpha with FoxO1a and hepatocyte nuclear factor 4alpha transcription factors.

UNLABELLED: Selenoprotein P (SeP), the major selenoprotein in plasma, is produced mainly by the liver, although SeP expression is detected in many organs. Recently, we reported stimulation of SeP promoter activity by the forkhead box transcription factor FoxO1a in hepatoma cells and its attenuation by insulin. Here, we demonstrate that this translates into fine-tuning of SeP production and secretion by insulin. Overexpression of peroxisomal proliferator activated receptor-gamma coactivator 1alpha (PGC-1alpha) enhanced the stimulatory effect of FoxO1a on SeP promoter activity. We identified a novel functional binding site for hepatocyte nuclear factor (HNF)-4alpha, termed hepatocyte nuclear factor binding element 1, in the human SeP promoter directly upstream of the FoxO-responsive element daf16-binding element 2 (DBE2). Point mutations in hepatocyte nuclear factor binding element 1 alone or together with DBE2 decreased basal activity and responsiveness of the SeP promoter to PGC-1alpha. Moreover, the PGC-1alpha-inducing glucocorticoid dexamethasone strongly enhanced SeP messenger RNA levels and protein secretion in cultured rat hepatocytes, whereas insulin suppressed the stimulation of both PGC-1alpha and SeP caused by dexamethasone treatment. In a brain-derived neuroblastoma cell line with low basal SeP expression, SeP transcription was stimulated by PGC-1alpha together with FoxO1a, and overexpression of HNF-4alpha potentiated this effect. CONCLUSION: High-level expression of SeP in liver is ensured by concerted action of the coactivator PGC-1alpha and the transcription factors FoxO1a and HNF-4alpha. Hence, the production of SeP is regulated similarly to that of the gluconeogenic enzyme glucose-6-phosphatase. As hepatic SeP production is crucial for selenium distribution throughout the body, the present study establishes PGC-1alpha as a key regulator of selenium homeostasis.

CD95 ligation and intracellular membrane flow.

Whereas ligation of the CD95 death receptor in the plasma membrane of so-called type I cells leads to a direct caspase 8-dependent activation of downstream effector caspases, mitochondrial amplification of caspase 8-derived signals is required in so-called type II cells in order to execute apoptotic cell death. In type I cells CD95L (CD95 ligand) binding to CD95 results in a ceramide-dependent formation of the DISC (death-inducing signalling complex) and caspase 8-dependent CD95 clustering in the plasma membrane, followed by an internalization of these multimeric-receptor-DISC complexes. In contrast, in the hepatocyte, a type II cell, the bulk of CD95 is stored intracellularly under resting conditions and only a few 'sentinel' CD95 receptors are present in the plasma membrane. However, their activation by CD95L is sufficient to trigger a caspase 8-dependent endosomal acidification and a ceramide-dependent trafficking of intracellularly stored CD95 to the plasma membrane, thereby amplifying CD95 activation. Thus, in both type I and type II cells, ceramide and CD95 receptor endo- and exo-cytosis are involved in CD95-mediated apoptosis, but apparently in different ways. This, however, is not the only effect of CD95 ligation on intracellular membrane flow in type II cells, and evidence has been presented that soon after CD95 ligation Golgi elements intermix caspase-dependently with mitochondria. In this issue of the Biochemical Journal, Matarrese et al. report another aspect on endocytosis in response to CD95 ligation in type II cells, namely a caspase-independent endocytosis with vesicle translocation to the mitochondrial compartment, suggestive of an interplay between both organelles in the sense of an 'organelle scrambling'. Thus early effects of CD95 activation on intracellular membrane flow may be much more complex than previously thought, but much has still to be learned about signalling mechanisms and the role they play in apoptosis.

[Granulated Proctosigmoiditis by Antibiotic-associated Infection with Pseudomonas Aeruginosa]. / Granulierende Proktosigmoiditis durch Antibiotika-assoziierte Pseudomonaden-Infektion.

HISTORY AND ADMISSION FINDINGS: We report on the case of an elderly patient with persisting diarrhea. Few weeks previous of admission the patient had received antibiotic therapy because of respiratory infection. On admission he seemed exsiccated and feeble. EXAMINATIONS: Macroscopic findings in colonoscopy showed proctosigmoiditis and membranous exsudations. Stool culture provided the evidence for an antibiotic-associated infection with pseudomonas aeruginosa. TREATMENT AND COURSE: The recommended oral therapy with ciprofloxacin proved to be effective. CONCLUSION: Complications with elderly patients are multimorbidity and diarrhea-induced prerenal failure. Frail patients can react strongly to antibiotic therapy with enteritis and dysbacteriosis.

Osmosensing and signaling in the regulation of mammalian cell function.

Volume changes of mammalian cells as induced by either anisoosmolarity or under isoosmotic conditions by hormones, substrates and oxidative stress critically contribute to the regulation of metabolism, gene expression and the susceptibility to stress. Osmosensing (i.e. the registration of cell volume) triggers signal transduction pathways towards effector sites (osmosignaling), which link alterations of cell volume to a functional outcome. This minireview summarizes recent progress in the understanding of how osmosensing and osmosignaling integrate into the overall context of growth factor signaling and the execution of apoptotic programs.

Hyperosmotic activation of the CD95 system.

Cell shrinkage, nuclear condensation, DNA fragmentation, and apoptotic body formation are hallmarks of programmed apoptotic cell death. Herein, apoptotic volume decrease (AVD) is an early and ubiquitous event. Conversely, in hepatocytes, hyperosmotic cell shrinkage leads to an activation of the CD95 death receptor system, which involves CD95 tyrosine phosphorylation, CD95 oligomerization, and subsequent trafficking of the CD95 to the plasma membrane, and sensitizes hepatocytes toward CD95 ligand (CD95L)-induced apoptosis. Early signaling events leading to CD95 activation by hyperosmolarity have been identified. In hepatocytes, hyperosmotic exposure induces an almost instantaneous acidification of an acidic sphingomyelinase (ASM) containing endosomal compartment, which is followed by an increase in the intracellular ceramide concentration. Inhibition of anion channels or the vacuolar-type H(+)-ATPase abolishes not only endosomal acidification and subsequent ceramide generation, but also the otherwise observed hyperosmotically induced generation of reactive oxygen species (ROS) by NADPH oxidase isoforms. Hyperosmolarity-induced ROS formation then leads to a Src-family kinase Yes-mediated activation of the epidermal growth factor receptor (EGFR) and to an activation of the c-Jun-N-terminal kinase (JNK). JNK then provides a signal for CD95/EGFR association and subsequent CD95 tyrosine phosphorylation, which is mediated by the EGFR tyrosine kinase activity. CD95 tyrosine phosphorylation then allows for CD95 receptor oligomerization, translocation of the CD95/EGFR protein complex to the plasma membrane, and formation of the death inducing signaling complex (DISC). Mild hyperosmotic exposure, that is, 405 mosmol/liter, does not lead to a reduction of cell viability, even if DISC formation and subsequent caspase 8 and 3 activation occur, but sensitizes hepatocytes to CD95L-induced apoptosis. However, activation of the CD95 system by a more severe hyperosmotic challenge (>505 mosmol/liter) is followed by execution of the apoptotic cell death. Other covalent modifications of CD95, such as CD95 tyrosine nitration or CD95 serine/threonine phosphorylation, were shown to inhibit the CD95 activation process.

Chronic liver disease is triggered by taurine transporter knockout in the mouse.

Taurine is an abundant organic osmolyte with antioxidant and immunomodulatory properties. Its role in the pathogenesis of chronic liver disease is unknown. The liver phenotype was studied in taurine transporter knockout (taut-/-) mice. Hepatic taurine levels were ~21, 15 and 6 mumol/g liver wet weight in adult wild-type, heterozygous (taut+/-) and homozygous (taut-/-) mice, respectively. Immunoelectronmicroscopy revealed an almost complete depletion of taurine in Kupffer and sinusoidal endothelial cells, but not in parenchymal cells of (taut-/-) mice. Compared with wild-type mice, (taut-/-) and (taut+/-) mice developed moderate unspecific hepatitis and liver fibrosis with increased frequency of neoplastic lesions beyond 1 year of age. Liver disease in (taut-/-) mice was characterized by hepatocyte apoptosis, activation of the CD95 system, elevated plasma TNF-alpha levels, hepatic stellate cell and oval cell proliferation, and severe mitochondrial abnormalities in liver parenchymal cells. Mitochondrial dysfunction was suggested by a significantly lower respiratory control ratio in isolated mitochondria from (taut-/-) mice. Taut knockout had no effect on taurine-conjugated bile acids in bile; however, the relative amount of cholate-conjugates acid was decreased at the expense of 7-keto-cholate-conjugates. In conclusion, taurine deficiency due to defective taurine transport triggers chronic liver disease, which may involve mitochondrial dysfunction.