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D Häussinger

Publications and source records attributed to D Häussinger.

At least 19 recordsLinked to original sources
PubMed1999

The mitogen-activated protein (MAP) kinase p38 and its upstream activator MAP kinase kinase 6 are involved in the activation of signal transducer and activator of transcription by hyperosmolarity.

Environmental stress (e.g. aniso-osmolarity and UV light), hypoxia/reoxygenation, and reactive oxygen species activate intracellular signaling cascades such as the "stress-responsive" mitogen-activated protein kinases and nuclear factor kappaB. We have recently shown that the Janus tyrosine kinase/signal transducer and activator of transcription (Jak/STAT) pathway is ligand-independently activated by hyperosmotic shock. In the present study, we show that besides STAT1 also the tyrosine phosphatase SHP2 became tyrosine-phosphorylated upon hyperosmolarity. SB 202190 and SB 203580 (specific inhibitors of p38) inhibited both STAT activation and tyrosine phosphorylation of SHP2 induced by hyperosmotic stress. Overexpression of wild-type p38 mitogen-activated protein kinase and its upstream activator mitogen-activated protein kinase kinase 6 (MKK6) resulted in an enhanced STAT1 tyrosine phosphorylation upon osmotic shock. Accordingly, overexpression of dominant negative mutants of p38 and MKK6 largely decreased hyperosmotic STAT1 activation and tyrosine phosphorylation of SHP2. Furthermore, we provide evidence that a genistein-sensitive tyrosine kinase different from Jak1 is involved in stress-activation of STAT1 and tyrosine phosphorylation of SHP2. These results strongly suggest that hyperosmotic shock activates STAT1 and SHP2 via p38 and its upstream activator MKK6.

Animals↗
PubMed1999

Dexamethasone- and osmolarity-dependent expression of the multidrug-resistance protein 2 in cultured rat hepatocytes.

Expression of the conjugate export pump multidrug-resistance protein 2 (MRP2) in liver is regulated by endotoxin and anti-tumour agents. This paper reports on the effects of dexamethasone and osmolarity on MRP2 expression. MRP2 expression was studied at the protein, mRNA, immunocytochemical and functional levels in cultured rat hepatocytes. Protein and mRNA expression of MRP2 in rat hepatocytes 24 and 48 h after isolation were largely dependent on the presence of dexamethasone (100 nmol/l) in the culture medium. MRP2 was localized at the pseudocanalicular membrane and increased expression of MRP2 was accompanied by a widening of the pseudocanaliculi. In presence of dexamethasone, hypo-osmolarity (205 mosmol/l) led to a strong induction of MRP2 mRNA and protein, whereas expression was decreased by hyperosmolarity (405 mosmol/l). Also, a decay of MRP2 protein and mRNA following dexamethasone withdrawal was osmosensitive. Expression of dipeptidylpeptidase IV, another canalicular protein, was unaffected by dexamethasone and osmolarity. It is concluded that glucocorticoids are strong inducers of MRP2 in liver. Besides short-term carrier insertion/retrieval, osmoregulation of MRP2 also involves a long-term effect on MRP2 expression.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

Anisoosmotic regulation of the Nopp140 mRNA in H4IIE rat hepatoma cells and primary hepatocytes.

Using the differential display polymerase chain reaction osmosensitive regulation of mRNA levels of the nucleolar phosphoprotein of 140 kDa (Nopp140) was found in H4IIE rat hepatoma cells. These levels were downregulated after hypoosmotic exposure in H4IIE cells and primary rat hepatocytes. Hyperosmotic incubation increased Nopp140 mRNA levels in H4IIE cells but not in hepatocytes. Inhibition of p38MAPK or MAP kinase kinase upstream of Erk-1 and Erk-2 decreased Nopp140 mRNA levels but did not prevent their osmosensitivity. Because Nopp140 is involved in the regulation of transcriptional activity it could play a role in the osmosignalling pathway towards gene expression in H4IIE cells and hepatocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Prior cytomegalovirus infection and the risk of restenosis after percutaneous transluminal coronary balloon angioplasty.

BACKGROUND: Restenosis is a common problem after all revascularization procedures in atherosclerotic coronary arteries. Reactivated human cytomegalovirus (CMV) has been detected in tissues of restenotic vascular lesions and was hypothesized to be a contributing pathogenic factor. Recent data suggest an association of restenosis after optimal coronary atherectomy with CMV serostatus, and a possible role of antiviral therapy was discussed. We therefore tested the hypothesis that prior CMV infection might be a risk factor for restenosis after conventional coronary balloon angioplasty (PTCA). METHODS AND RESULTS: We analyzed 92 consecutive patients who had been admitted for control angiography after previous PTCA within a mean interval of 6 months. Anti-CMV antibodies were measured as an indicator of prior CMV infection and latency. The coronary angiograms before PTCA, directly after, and 6 months later were analyzed quantitatively. Sixty-five percent of the patients were CMV-positive. Before PTCA, the degree (mean+/-SD) of stenosis was 69+/-10% in CMV-positive and 68+/-8.3% in CMV-negative subjects. PTCA resulted in a residual stenosis of 39% in both groups. After 6 months, the late losses of luminal diameter in the CMV-positive and -negative groups were 11+/-13% and 12+/-15%, respectively (P=0.658). In an ANCOVA with 25 potential risk factors for restenosis, CMV serostatus was not significantly associated with restenosis development. CONCLUSIONS: Our data indicate that prior CMV infection, in contrast to optimal atherectomy, is not associated with chronic restenosis after conventional coronary balloon angioplasty. The results do not support a possible benefit from antiviral therapy.

Adult↗
PubMed1999

Regulation of CD95 (Apo-1/Fas) ligand and receptor expression in squamous-cell carcinoma by interferon-gamma and cisplatin.

CD95 (Apo-1/Fas) ligand (CD95L) expression has been observed in various malignancies. In human primary cell lines from a squamous cell carcinoma (SCC) of the vulva, the effect of cisplatin (CDDP) and IFNgamma on the expression of CD95L and its 2 receptor isoforms, CD95 transmembrane (CD95tm) and CD95 soluble receptor, was studied at the mRNA and protein levels. Addition of CDDP and IFNgamma increased CD95L mRNA levels in the primary cell line 6-fold and 1.7-fold, respectively. In comparison, CD95tm mRNA levels were diminished by CDDP but increased 8-fold upon IFNgamma challenge. CD95L expressed by SCC cells was functionally relevant since these cells were able to induce CD95-specific apoptosis in autologous lymphocytes from the SCC-bearing patient. Thus, CD95L expression in SCC may contribute to tumor-associated immunosuppression, which may be modulated by CDDP and IFNgamma. In tumor samples of the primary SCC, CD95L expression was enhanced in the area of the border between invasive tumor tissue and surrounding stroma cells. The locally restricted over-expression of CD95L was congruent with the arrangement of apoptotic stroma cells in the direct vicinity of invading tumor tongues, suggesting a role as invasion factor for CD95L.

Antineoplastic Agents↗
PubMed1999

CD95 ligand expression in dedifferentiated breast cancer.

CD95 ligand expression has been observed in various malignancies. Studying the CD95 ligand (CD95L) and receptor (CD95) system in eight non-malignant mammary tissues and 40 breast cancer tissues, mRNA and protein expression was determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescence. mRNA levels of CD95L correlated positively (r=0.90; p< 0.01) and transmembrane CD95 inversely (r=-0.88; p< 0.01) with histopathological grading of the breast tumours: CD95L mRNA levels were low in adenomas, but increased by 20-fold in grade I, 120-fold in grade II, and 310-fold in grade III breast cancer. In contrast, CD95 mRNA levels were low in high-grade carcinomas, but high in benign mammary tissues. Since CD95L acts as an efficient inducer of apoptosis in CD95(+) cells, apoptotic cells were identified on the tissue sections. Tumour-infiltrating lymphocytes and stromal cells in close proximity to CD95L-expressing breast cancer underwent apoptosis. As a functional test, CD95(+) target cells were cultured on breast cancer tissue sections. The target cells underwent apoptosis when cultured on breast cancer sections, but could be rescued when CD95L was specifically blocked by a CD95-Fc fusion molecule. The data suggest an inverse regulation of CD95 ligand and receptor expression during dedifferentiation of breast cancer. Killing of bystander cells by the CD95L-expressing breast tumour could be involved in tissue invasion.

Adult↗
PubMed1999

Color doppler sonography avoids misinterpretation of the "parallel channel sign" in the sonographic diagnosis of cholestasis.

PURPOSE: The intrahepatic "parallel channel sign" on gray-scale sonograms is generally interpreted as representing dilated bile ducts, but it may also be caused by enlargement of intrahepatic arteries. This study was performed to evaluate the incidence of misinterpretation of the parallel channel sign without color Doppler sonography and the characteristics of patients in whom misinterpretation of the parallel channel sign is likely to occur. METHODS: A total of 1,100 patients were examined by sonography. All patients with a parallel channel sign on gray-scale sonograms underwent color Doppler sonography. In addition, laboratory values related to cholestasis were measured. RESULTS: The parallel channel sign was observed in 57 patients (5.2%). In 35 (61%) of these patients, color Doppler sonography revealed blood flow in both lumina, indicating that the parallel channel sign was not caused by enlarged bile ducts. Eighty-six percent of this group had nonbiliary liver disease; the enlarged hepatic artery branches were associated with liver cirrhosis in 63% of this group. Color Doppler sonography confirmed that the other 22 patients (39%) had an enlarged intrahepatic bile duct. CONCLUSIONS: Use of color Doppler sonography can help avoid misinterpretation of the parallel channel sign, especially in patients with nonbiliary liver disease.

Cholestasis↗
PubMed1999

Organic osmolyte transport in quiescent and activated rat hepatic stellate cells (Ito cells).

Activation of hepatic stellate cells (HSCs) results in multiple alterations of cell function, but nothing is known about organic osmolytes in these cells. Organic osmolyte transport and transporter messenger RNA (mRNA) expression was studied in quiescent rat HSCs and after their transformation into alpha1-smooth muscle actin-positive myofibroblastlike cells. Quiescent stellate cells expressed in an osmosensitive manner the mRNA levels of the transporters for taurine (TAUT) and myoinositol (SMIT), whereas that for betaine was not detectable. However, these cells showed osmosensitive uptake not only of taurine and myoinositol but also of betaine. Osmosensitive betaine uptake was mediated by amino acid transport system A. After transformation into myofibroblasts, taurine and myoinositol uptake increased 5.5-fold and 4.5-fold, respectively, together with the respective transporter mRNA levels. Betaine uptake increased twofold because of osmosensitive induction of BGT1 expression. In both quiescent and activated HSCs, hypoosmotic cell swelling induced a rapid and 4, 4'-diisothiocyanatostilbene-2,2'-disulphonic acid-sensitive osmolyte efflux. In quiescent HSCs, hyperosmotic exposure increased the messenger RNA (mRNA) level of cyclooxygenase-2, which was counteracted by taurine but not by betaine or myoinositol. The study identifies taurine, myoinositol, and betaine as osmolytes in HSCs. Transformation of HSCs is accompanied by enhanced osmolyte transport activity and induction of the BGT1 transporter, which may be another activation marker of HSCs.

Actins↗
PubMed1999

Release of osmolytes from perfused rat liver on perivascular nerve stimulation: alpha-adrenergic control of osmolyte efflux from parenchymal and nonparenchymal liver cells.

The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied in the intact perfused rat liver and isolated liver parenchymal cells (PC) and nonparenchymal cells. In the perfused liver, electrical stimulation of perivascular nerves (20 Hz/2 ms/20 V) led to a phentolamine-sensitive increase of cell hydration by 6.5% +/- 1.2% (n = 3) and a transient phentolamine-sensitive stimulation of taurine and inositol, but not betaine, release. These nerve effects were mimicked by phenylephrine, but not prostaglandin F2alpha, and were not affected by sodium nitroprusside (SNP) or ibuprofen. Nerve stimulation-induced taurine, but not inositol, release was inhibited by 4, 4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS) (50 micromol/L). Single-cell fluorescence studies with isolated liver PC, Kupffer cells (KC), sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) revealed that phenylephrine induced an increase in cytosolic free Ca2+ only in PC and HSC, but not in KC and SEC, whereas extracellular uridine triphosphate (UTP) produced Ca2+ transients/oscillations in all liver cell types studied. Phenylephrine had no effect on osmolyte release from isolated KC and SEC, but increased taurine (but not inositol) release from PC and inositol (but not taurine) efflux from HSC. The data suggest that: 1) liver cell hydration and-consecutively-osmolyte content are modulated by hepatic nerves via an alpha-adrenergic mechanism, which does not involve eicosanoids or hemodynamic changes; 2) that PC and HSC are the primary targets for nerve-dependent alpha-adrenergic activation, whereas 3) KC and SEC probably do not express alpha-adrenoceptors coupled to Ca2+ mobilization or osmolyte efflux.

Adrenergic alpha-Agonists↗
PubMed1999

Involvement of soluble CD95 in Churg-Strauss syndrome.

Deficiency of CD95 (Apo-1/Fas)-mediated apoptosis has recently been found in some autoimmune lymphoproliferative disorders due to inherited mutations of the CD95 gene. In this study, impairment of CD95 ligand-mediated killing of lymphocytes and eosinophils in Churg-Strauss Syndrome (CSS), which was a result of variation of CD95 receptor isoform expression, is demonstrated. Compared to those from healthy individuals, peripheral blood lymphocytes from eight CSS patients exhibit a switch from the membrane-bound CD95 receptor expression to its soluble splice variant, which protects from CD95L-mediated apoptosis. In five out of seven CSS patients recurrent oligoclonal T cell expansions were found, all using a Vbeta-gene from the Vbeta21 family associated with similar CDR3 motifs, indicating the predominance of T cell clones of a similar specificity in the CSS patients. In two of them, the effect of immunosuppressive therapy was studied. In both cases aberrant overexpression of the soluble CD95 receptor isoform and deviations from normal TCR Vbeta-gene usage normalized in parallel with the clinical improvement. Furthermore, soluble CD95 was identified as a survival factor for eosinophils rescuing eosinophils from apoptosis in the absence of growth factors in vitro. Given the role of eosinophils as effector cells in CSS, these findings suggest that soluble CD95 may be mechanistically involved in the disease.

Adult↗
PubMed1999

Involvement of p38MAPK in the regulation of proteolysis by liver cell hydration.

BACKGROUND & AIMS: Liver cell hydration is a major determinant of proteolysis control; however, the underlying mechanisms are unknown. METHODS: The role of mitogen-activated protein kinases for proteolysis control was studied in perfused rat liver. RESULTS: Hyposmolarity led to a rapid activation of Erk-2 and p38(MAPK), but not of c-Jun-N-terminal kinase 1. Likewise, isosmotic cell swelling induced by insulin, ethanol, or glutamine/glycine activated p38(MAPK). Inhibition of hyposmotic Erk activation by pertussis or cholera toxin, erbstatin, or genistein had no effect on the swelling-induced inhibition of proteolysis. Likewise, wortmannin, rapamycin, and okadaic acid were ineffective, but proteolysis recovery from hyposmotic inhibition was okadaic acid sensitive. SB203580, an inhibitor of p38(MAPK), abolished both the antiproteolytic effect of hyposmotic cell swelling and the hyposmolarity-induced inhibition of autophagic vacuole formation. Also, the antiproteolytic effect of isotonic cell swelling induced by ethanol, glutamine/glycine, or insulin was abolished by SB203580, but not the swelling potency of these agents. SB203580 had no effect on the cell hydration-independent control of proteolysis exerted by NH4Cl, asparagine, or phenylalanine. CONCLUSIONS: The data suggest an important role of p38(MAPK) in the regulation of autophagic proteolysis by cell volume in liver.

Animals↗
PubMed1999

Regulation of the multidrug resistance protein 2 in the rat liver by lipopolysaccharide and dexamethasone.

BACKGROUND & AIMS: Endotoxin lipopolysaccharide (LPS) induces cholestasis and down-regulates the multidrug resistance protein 2 (MRP2). This study intends to characterize the short-term effects of LPS on MRP2. METHODS: The effects of LPS and dexamethasone on excretion of bromosulphalein (BSP), MRP2 messenger RNA (mRNA) levels, and subcellular MRP2 localization were studied by means of liver perfusion, Northern blots, and confocal microscopy. RESULTS: LPS treatment for 3-12 hours decreased biliary BSP excretion (10 micromol/L) by 40%. Hyposmolarity stimulated BSP excretion to control levels 3 hours after LPS injection, but was ineffective after 12 hours or in saline-treated controls. LPS led to a strong decrease of MRP2 mRNA after 12 hours, but not during the first 6 hours. LPS induced the appearance of MRP2 in intracellular vesicles in the immediate vicinity of the canaliculi within 3 hours, and these vesicles were remote from the canaliculi after 6 and 12 hours. The MRP2-containing vesicles did not stain for dipeptidylpeptidase IV (DPPIV). Dexamethasone counteracted the LPS effects on MRP2 mRNA levels, subcellular distribution, and BSP excretion. CONCLUSIONS: LPS induces cholestasis due to an early retrieval of MRP2 from the canalicular membrane, whereas down-regulation of MRP2 mRNA is a later event. LPS-induced MRP2 retrieval from the canalicular membrane is not associated with the retrieval of DPPIV, suggestive for selectivity of the process.

Animals↗
PubMed1999

Involvement of CD95 (Apo-1/Fas) ligand expressed by rat Kupffer cells in hepatic immunoregulation.

BACKGROUND & AIMS: CD95 (Apo-1/Fas) ligand suppresses inflammatory responses in immune-privileged organs. In this study, modulation of the hepatic CD95 receptor/ligand system by interferon gamma and cyclosporin A was investigated. METHODS: CD95 receptor and ligand expression were measured at the messenger RNA level by using quantitative reverse-transcription polymerase chain reaction and immunocytochemistry in primary cultures of rat Kupffer cells, hepatocytes, and T lymphocytes. Soluble CD95 in culture supernatants was detected by enzyme-linked immunosorbent assay and apoptosis by the TUNEL method. RESULTS: Interferon gamma treatment led to an increase in CD95 ligand messenger RNA levels in Kupffer cells followed by an overexpression of the soluble CD95 receptor. Supernatants derived from 24-hour but not from 48-hour interferon gamma-treated Kupffer cells killed lymphocytes by a CD95-dependent mechanism. Cyclosporin A inhibited CD95 ligand expression in Kupffer cells and lymphocyte killing. In liver parenchymal cells, interferon gamma increased messenger RNA levels of the transmembrane CD95 isoform and sensitivity of these cells toward CD95-mediated apoptosis. CONCLUSIONS: The expression pattern of CD95 receptor and ligand in response to interferon gamma points to a coordinated interplay between Kupffer cells, hepatocytes, and T lymphocytes in which Kupffer cells may regulate programmed cell death of T lymphocytes and hepatocytes.

Animals↗
PubMed1999

Hepatosplenomegalic lipidosis: what unless Gaucher? Adult cholesteryl ester storage disease (CESD) with anemia, mesenteric lipodystrophy, increased plasma chitotriosidase activity and a homozygous lysosomal acid lipase -1 exon 8 splice junction mutation.

A 36-year-old woman was admitted for hepatosplenomegaly and anemia. Bone marrow cytology showed "sea-blue histiocytes", vacuolated macrophages and plasma cells. As primary liver disease, malignancy or hematologic disorders were excluded, and plasma chitotriosidase activity was increased 27-fold over control, the presence of a lysosomal storage disease was suspected. Biochemical analysis of skin fibroblasts revealed normal glucocerebrosidase and sphingomyelinase activity, but lipid analysis showed a more than 15-fold accumulation of cholesterol esters within the cells. The activity of lysosomal acid lipase (LAL) in fibroblast homogenates was decreased to 12% of control subjects. Mutational analysis of the patient's blood showed the homozygous G-->A mutation at position -1 of the exon 8 splice donor site (E8SJM-allele) known for adult cholesteryl ester storage disease (CESD); the polymorphic background was that of the complex haplotype -6Thr, 2Gly, 894 G-->A. Based on clinical, laboratory, cytological and and biochemical findings, CESD can clearly be separated from other more frequent inherited lysosomal storage diseases, e.g. atypical forms of Gaucher disease.

Adult↗
PubMed1999

Extraesophageal autonomic dysfunction in patients with achalasia.

A disagreement exists as to whether extraintestinal parasympathetic autonomic function is altered in patients with esophageal achalasia. Therefore, we assessed autonomic dysfunction in esophageal achalasia and considered the most relevant parameters of parasympathetic autonomic function in these patients. In a prospective study, heart rate variation and pupillary function were investigated in 15 patients with achalasia of the esophagus and in 15 controls by application of a battery of standardized autonomic function tests. Significant differences between patients and controls were detected for various parameters of heart rate variation and pupillometry. When compared to values obtained from large groups of healthy subjects, none of the controls but 11 patients had at least one abnormal parameter of parasympathetic autonomic function. It is suggested that in esophageal achalasia parasympathetic dysfunction that extends beyond the gastrointestinal tract can be frequently detected. This finding supports the view of a generalized alteration of the autonomic nervous system in achalasia.

Adult↗
PubMed1999

Supraphysiologic concentrations of cerulein induce apoptosis in the rat pancreatic acinar cell line AR4-2J.

Little is known as yet about the role of apoptosis in pancreatic damage. This study evaluated the effects of supraphysiologic concentrations of the cholecystokinin (CCK) analog, cerulein, which causes cell damage in vitro and acute pancreatitis in vivo, on cell proliferation and DNA fragmentation in the rat pancreatic acinar cell line AR4-2J. Cerulein inhibited the cell proliferation of AR4-2J time- and dose-dependently to approximately 60% of the control level at 10(-6) M after 72 h. DNA fragmentation, as assessed by both electrophoresis and enzyme-linked immunosorbent assay (ELISA), occurred at cerulein concentrations > or = 10(-8) M. The maximal DNA fragmentation as measured by ELISA was reached after 24 h. Cerulein at concentrations > or = 10(-9) M induced wild-type p53. Glutathione (1 mM) diminished the effects of cerulein on both cell proliferation and DNA fragmentation, whereas spermine (100 microM), which partially attenuated DNA fragmentation, did not have an effect on cell proliferation. The CCK-A-receptor antagonist loxiglumide completely abolished the effect of cerulein on DNA fragmentation. The serine-protease inhibitor FUT-175 (10 microM), the cysteine-protease inhibitor NCO-700 (5 mM), and ethylene glycol tetraacetic acid (EGTA; 500 microM) all had no effects on the changes in cell proliferation and DNA fragmentation induced by cerulein. The data suggest that supraphysiologic concentrations of cerulein rapidly induce apoptosis in AR4-2J cells and only later inhibit cell proliferation. These effects are mediated by CCK-A receptors. Cerulein-induced apoptosis may involve the induction of wild-type p53 or glutathione depletion or both.

Animals↗
PubMed1999

Effects of hyper- and hypoosmolality on whole body protein and glucose kinetics in humans.

To investigate the effect of acute changes of extracellular osmolality on whole body protein and glucose metabolism, we studied 10 male subjects during three conditions: hyperosmolality was induced by fluid restriction and intravenous infusion of hypertonic NaCl [2-5%; (wt/vol)] during 17 h; hypoosmolality was produced by intravenous administration of desmopressin, liberal water drinking, and infusion of hypotonic saline (0.4%); and the isoosmolality study consisted of ad libitum oral water intake by the subjects. Leucine flux ([1-13C]leucine infusion technique), a parameter of whole body protein breakdown, decreased during the hypoosmolality study (P < 0. 02 vs. isoosmolality). The leucine oxidation rate decreased during the hypoosmolality study (P < 0.005 vs. isoosmolality). Metabolic clearance rate of glucose during hyperinsulinemic-euglycemic clamping increased less during the hypoosmolality study than during the isoosmolality study (P < 0.04). Plasma insulin decreased, and plasma nonesterified fatty acids, glycerol, and ketone body concentrations and lipid oxidation increased during the hypoosmolality study. It is concluded that acute alterations of plasma osmolality influence whole body protein, glucose, and lipid metabolism; hypoosmolality results in protein sparing associated with increased lipolysis and lipid oxidation and impaired insulin sensitivity.

Adult↗