PubMed Health⌕ Search

Biomedical subjects

G Sass

Publications and source records attributed to G Sass.

At least 19 recordsLinked to original sources
PubMed2002

TNF tolerance and cytotoxicity in the liver: the role of interleukin-1beta, inducible nitric oxide-synthase and heme oxygenase-1 in D-galactosamine-sensitized mice.

OBJECTIVE AND DESIGN: Pretreatment with tumor necrosis factor (TNF)-alpha induces tolerance towards itself in experimental liver injury. MATERIAL AND TREATMENT: To study mechanisms of TNF tolerance we used knockout mice for either TNF-receptor-2 (TNFR-2), inducible nitric oxide (NO)-synthase (iNOS) or caspase-1 (ICE) or inhibited heme oxygenase-1 (HO-1) by treatment with zinc-protoporphyrin 9. Liver damage was induced by administration of TNF to mice sensitized with D-galactosamine (GalN). Tolerance was induced by pretreatment with low doses of TNF. METHODS: Severity of liver injury was assessed by determination of plasma transaminases and apoptosis. Time courses of intra-hepatic iNOS, interleukin-1beta (IL-1beta) and HO-1 expression after TNF treatment were measured by reverse transcription polymerase chain reaction (RT-PCR). TNF-receptor-1 (TNFR-1) expression was determined by immunofluorescent staining. RESULTS: TNF-pretreatment did not affect TNFR-1 expression in the liver and resulted in time dependent up-regulation of iNOS, IL-1beta and HO-1. TNF- pretreated TNFR-2, iNOS or ICE knockout mice were as sensitive towards GalN/TNF as the wild type, while mice with impaired HO-1 activity were even more sensitive, but tolerance was inducible in all TNF-pretreated mice. CONCLUSIONS: TNF tolerance towards GalN/TNF treatment is mediated by TNFR-1. IL-1beta, iNOS and HO-1 neither mediated TNF-tolerance nor TNF cytotoxicity.

Animals↗
PubMed2001

Chronic inflammation and protection from acute hepatitis in transgenic mice expressing TNF in endothelial cells.

Endothelial activation is an important feature of many inflammatory diseases and has been implicated as the cause of vascular complications in disorders such as diabetes, atherosclerosis, and transplant rejection. One of the most potent activators of the endothelium is TNF, which can also be expressed by endothelial cells, causing a permanent, autocrine stimulatory signal. To establish a model of continuous endothelial activation and to elucidate the role of endothelial derived TNF in vivo, we generated transgenic mice expressing a noncleavable transmembrane form of TNF under the control of the endothelial-specific tie2 promoter. Adult tie2-transmembrane TNF-transgenic mice developed chronic inflammatory pathology in kidney and liver, characterized by perivascular infiltration of mononuclear cells into these organs. Along with the infiltrate, an up-regulation of the adhesion molecules ICAM-1 and VCAM-1, but not E-selectin, in the endothelium was observed. Despite predisposition to chronic inflammation these mice were protected from immune-mediated liver injury in a model of Con A-induced acute hepatitis. Although the blood levels of soluble TNF and IFN-gamma were increased in transgenic animals after challenge with Con A, no damage of hepatocytes could be detected, as assessed by the lack of increase in plasma transaminase activities and the absence of TUNEL staining in the liver. We conclude that expression of transmembrane TNF in the endothelium causes continuous endothelial activation, leading to both proinflammatory and protective events.

Acute Disease↗
PubMed2001

Dissection of the intracellular pathways in hepatocytes suggests a role for Jun kinase and IFN regulatory factor-1 in Con A-induced liver failure.

Con A administration results in dose-dependent immune-mediated liver injury. Cytokines are important to determine the outcome of liver failure in this model, and especially TNF-alpha and IFN-gamma directly contribute to hepatocyte damage. The intracellular pathways of these two cytokines, which eventually result in tissue destruction, are not well defined. Here we used anti-IFN-gamma Abs and adenoviral vectors that express molecules inhibiting distinct TNF-alpha-dependent pathways in hepatocytes to better understand the relevance of specific intracellular signaling cascades for Con A-induced liver failure. We show that activation of TNF-alpha- and IFN-gamma-dependent intracellular pathways occurs prior to the influx of immune-activated cells into the liver and that anti-TNF-alpha and anti-IFN-gamma neutralizing Abs cannot block infiltration of these cells. Blocking experiments with Abs and adenoviral vectors showed that NF-kappaB activation and the Fas-associated death domain protein/caspase 8 cascade in hepatocytes during Con A-induced liver failure have no impact on tissue injury. Additionally, STAT1 activation alone after Con A injection in liver cells does not result in liver damage. In contrast, IFN-gamma-dependent expression of IFN regulatory factor-1 and TNF-alpha-dependent activation of c-Jun N-terminal kinase in liver cells correlates with liver cell damage after Con A injection. Therefore, our experiments indicate that 11418690

Adaptor Proteins, Signal Transducing↗
PubMed2001

TNF-alpha-induced expression of adhesion molecules in the liver is under the control of TNFR1--relevance for concanavalin A-induced hepatitis.

TNF-alpha has been clearly identified as central mediator of T cell activation-induced acute hepatic injury in mice, e.g., Con A hepatitis. In this model, liver injury depends on both TNFRs, i.e., the 55-kDa TNFR1 as well as the 75-kDa TNFR2. We show in this report that the hepatic TNFRs are not transcriptionally regulated, but are regulated by receptor shedding. TNF directly mediates hepatocellular death by activation of TNFR1 but also induces the expression of inflammatory proteins, such as cytokines and adhesion molecules. Here we provide evidence that resistance of TNFR1(-/-) and TNFR2(-/-) mice against Con A hepatitis is not due to an impaired production of the central mediators TNF and IFN-gamma. Con A injection results in a massive induction of ICAM-1, VCAM-1, and E-selectin in the liver. Lack of either one of both TNFRs did not change adhesion molecule expression in the livers of Con A-treated mice, presumably reflecting the fact that other endothelial cell-activating cytokines up-regulated adhesion molecule expression. However, treatment of TNFR1(-/-) and TNFR2(-/-) mice with murine rTNF revealed a predominant role for TNFR1 for the induction of hepatic adhesion molecule expression. Pretreatment with blocking Abs against E- and P-selectin or of ICAM(-/-) mice with anti-VCAM-1 Abs failed to prevent Con A hepatitis, although accumulation of the critical cell population, i.e., CD4(+) T cells was significantly inhibited. Hence, up-regulation of adhesion molecules during acute hepatitis unlikely contributes to organ injury but rather represents a defense mechanism.

Animals↗
PubMed2001

Low-molecular-weight hyaluronic acid induces nuclear factor-kappaB-dependent resistance against tumor necrosis factor alpha-mediated liver injury in mice.

Liver resident NK1.1+ T cells are supposed to play a pivotal role in the onset of inflammatory liver injury in experimental mouse models such as concanavalin A (Con A)-induced hepatitis. These cells, expressing the adhesion receptor, CD44, are largely depleted from the liver by a single intravenous injection of low-molecular-weight fragments of hyaluronic acid (LMW-HA). Here, we report that LMW-HA pretreatment protected mice from liver injury in several models of T-cell- and macrophage-dependent, tumor necrosis factor alpha (TNF-alpha)-mediated inflammatory liver injury, i.e., from liver injury induced by either Con A or Pseudomonas exotoxin A (PEA) or PEA/lipopolysaccharide (LPS). Interestingly, apart from inhibition of cellular adhesion, pretreatment of mice with LMW-HA was also capable of preventing hepatocellular apoptosis and activation of caspase-3 induced by direct administration of recombinant murine (rmu) TNF-alpha to D-galactosamine (GalN)-sensitized mice. LMW-HA-induced hepatoprotection could be neutralized by pretreatment with the nuclear factor-kappaB (NF-kappaB) inhibitor, pyrrolidine dithiocarbamate (PDTC), demonstrating the involvement of NF-kappaB in the observed protective mechanism. Indeed, injection of LMW-HA rapidly induced the production of TNF-alpha by Kupffer cells and the translocation of NF-kappaB into hepatocellular nuclei. Both LMW-HA-induced TNF-alpha production and NF-kappaB translocation were blocked by pretreatment with PDTC. Our findings provide evidence for an unknown mechanism of LMW-HA-dependent protection from inflammatory liver disease, i.e., induction of TNF-alpha- and NF-kappaB-dependent cytoprotective proteins within the target parenchymal liver cells.

ADP Ribose Transferases↗
PubMed2001

Inducible nitric oxide synthase is critical for immune-mediated liver injury in mice.

Concanavalin A (Con A) causes severe TNF-alpha-mediated and IFN-gamma-mediated liver injury in mice. In addition to their other functions, TNF-alpha and IFN-gamma both induce the inducible nitric oxide (NO) synthase (iNOS). Using different models of liver injury, NO was found to either mediate or prevent liver damage. To further elucidate the relevance of NO for liver damage we investigated the role of iNOS-derived NO in the Con A model. We report that iNOS mRNA was induced in livers of Con A-treated mice within 2 hours, with iNOS protein becoming detectable in hepatocytes as well as in Kupffer cells within 4 hours. iNOS-/- mice were protected from liver damage after Con A treatment, as well as in another TNF-alpha-mediated model that is inducible by LPS in D-galactosamine-sensitized (GalN-sensitized) mice. iNOS-deficient mice were not protected after direct administration of recombinant TNF-alpha to GalN-treated mice. Accordingly, pretreatment of wild-type mice with a potent and specific inhibitor of iNOS significantly reduced transaminase release after Con A or GalN/LPS, but not after GalN/TNF-alpha treatment. Furthermore, the amount of plasma TNF-alpha and of intrahepatic TNF-alpha mRNA and protein was significantly reduced in iNOS-/- mice. Our results demonstrate that iNOS-derived NO regulates proinflammatory genes in vivo, thereby contributing to inflammatory liver injury in mice by stimulation of TNF-alpha production.

Animals↗
PubMed2000

Functional and structural defects in HIV type 1 nef genes derived from pediatric long-term survivors.

DNA sequences and three distinct in vitro functions of Nef were evaluated in a group of seven perinatally infected children. nef gene sequences obtained before and after virus culture showed that one of the five non-/slow progressors harbored a virus with large deletions. nef genes from the remaining four children were full length but contained discrete changes at a higher frequency than the rapid progressors. In functional studies, 40 of 44 Nef proteins derived from the whole study group were capable of binding the cellular serine kinase p62, indicating that this function is well conserved among naturally occurring viruses. In contrast, representative Nef proteins derived from the long-term non-/slow progressors were found to be defective or far less capable of enhancing viral replication and/or viral infectivity in herpesvirus saimiri-transformed human T cells and peripheral blood mononuclear cells. On reversion of highly prevalent point mutations in the defective proteins, viral replication could be restored to wild-type levels. Our results suggest that nef genes derived from pediatric long-term nonprogressors have gross deletions in isolated cases but a higher prevalence of discrete changes that may impair Nef function in primary T cell assays, but not all functions reported for Nef.

Adolescent↗
PubMed1998

Phase I trial of weekly scheduling and pharmacokinetics of titanocene dichloride in patients with advanced cancer.

PURPOSE: To determine the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLTs) of a weekly schedule of titanocene dichloride (TD) and to define the pharmacokinetics of titanium in plasma and urine. PATIENTS AND METHODS: Twenty patients with a median age of 58 years received 83 courses of TD. TD was given as 1-hour infusion at escalating doses from 70 to 185 mg/m2/wk. Pharmacokinetic analysis was performed in eight patients for total plasma titanium (TPTi) and in three patients for ultrafiltrable titanium (UFTi). RESULTS: At the fifth dose level (185 mg/m2/wk), a variety of DLTs were seen in five patients: fatigue in three, bilirubinemia in one, and hypokalemia in two. A further six patients were treated at 140 mg/m2; only one had dose-limiting creatinine elevation and this dose was therefore defined as the MTD. No myelosuppression or alopecia were observed. One patient with adenocarcinoma of unknown primary had a minor response. Pharmacokinetic analysis showed that TPTi maximum concentration (Cmax) values were linear with dose and elimination of TPTi was triphasic with a long terminal half-life (t1/2; median, 165 hours; range, 89 to 592). Between 7% and 24.3% of the total of administered titanium was eliminated in urine over the first 24 hours. In contrast, UFTi elimination was described by a one-compartment model with a t1/2 of 0.41 hours; peak levels of UFTi were 5.2% +/- 2.5% those of TPTi. CONCLUSION: The MTD of TD given on a weekly schedule is 140 mg/m2, with cumulative, but reversible creatinine and bilirubin elevation being the DLTs.

Adult↗
PubMed1998

Phase I clinical and pharmacokinetic study of titanocene dichloride in adults with advanced solid tumors.

This Phase I dose-escalation clinical trial of a lyophilized formulation of titanocene dichloride (MKT4) was conducted to determine the maximum tolerated dose, the dose-limiting toxicity (DLT), and pharmacokinetics of titanium (Ti) after a single i.v. infusion of MKT4. Forty patients with refractory solid malignancies were treated with a total of 78 courses. Using a modified Fibonacci scheme, 15 mg/m2 initial doses of titanocene dichloride were increased in cohorts of three patients up to level 11 (560 mg/m2) if DLT was not observed. The maximum tolerated dose was 315 mg/m2, and nephrotoxicity was DLT. Two minor responses (bladder carcinoma and non-small cell lung cancer) were observed. The pharmacokinetics of plasma Ti were assessed in 14 treatment courses by atomic absorption spectroscopy. The ratio for the area under the curve(0-infinity) in plasma and whole blood was 1.2. The following pharmacokinetic parameters were determined for plasma, as calculated in a two-compartment model: biological half-life t1/2beta in plasma was 22.8+/-11.2 h (xh +/- pseudo-SD), peak plasma concentration cmax approximately 30 microg/ml at a dose of 420 mg/m2, distribution volume Vss= 5.34+/-2.1 L (xa +/- SD), and a total clearance CItotal = 2.58+/-1.23 ml/min (xa +/- SD). There was a linear correlation between the area under the curve(0-infinity) of Ti in plasma and the titanocene dichloride dose administered with a correlation coefficient r2 of 0.8856. Plasma protein binding of Ti was in the 70-80% range. Between 3% and 16% of the total amount of Ti administered were renally excreted during the first 36 h. The recommended dose for Phase II evaluation is 240 mg/m2 given every 3 weeks with i.v. hydration to reduce renal toxicity.

Adult↗
PubMed1997

The N-terminus of Nef from HIV-1/SIV associates with a protein complex containing Lck and a serine kinase.

The Nef protein of human and primate lentiviruses is a key factor in HIV/SIV pathogenesis. Here we report that Nef associates with two different kinases, forming a multiprotein complex at the far N-terminus of the viral protein. One of the kinases was identified as Lck, whereas the second protein was found to be a serine kinase that phosphorylated Nef and Lck in vitro and could be discriminated from the serine kinase identified previously. The Nef-associated kinase complex (NAKC) was demonstrated in COS cells, in HIV-infected cells, and in vitro using recombinant Lck and Nef proteins. Deletion of a short amphipathic alpha-helix in the N-terminus, which was found to be conserved in all Nef proteins, inhibited association of the NAKC and significantly reduced virion infectivity.

Amino Acid Sequence↗
PubMed1996

Antitumor activity of treosulfan in human lung carcinomas.

Treosulfan (L-threitol 1,4-bismethanesulfonate, Ovastat) is an alkylating agent and a structural analogue of busulfan. It has been established in the clinical chemotherapy of human ovarian carcinomas for several years and has additionally been shown to be effective against xenografted human breast carcinomas. No other human carcinoma is yet known to be sensitive to treosulfan. The present study confirms the pronounced and significant antitumor activity of treosulfan against heterotransplanted human lung carcinomas of both the small-cell and the non-small-cell type. Treosulfan reduced the growth of all four small-cell lung carcinomas that were investigated in a significant manner. It was even more active than equitoxic doses of the clinically approved cytostatics ifosfamide, cisplatin, and etoposide toward three of them and induced long-lasting growth reductions (60-98% of control tumor size) corresponding to partial and nearly complete remissions. In the case of the nine non-small-cell lung carcinomas investigated, treosulfan effected significant growth inhibition of more than 50%, again in all of them, and was more active than the comparative compounds ifosfamide, mitomycin C, and cisplatin at least in one of four epidermoid lung carcinomas, one large-cell carcinoma, and one of three lung adenocarcinomas. These results are remarkable and unexpected, and the present study should be followed rapidly by phase II clinical trials of treosulfan against human lung carcinomas of both the small-cell and the non-small-cell type.

Animals↗
PubMed1995

In vitro activity of titanocenedichloride versus cisplatin in four ovarian carcinoma cell lines evaluated by a microtiter plate ATP bioluminescence assay.

Titanocenedichloride (MKT 4) is a novel anticancer drug with a broad spectrum of activity in mammalian tumors. We investigated the anticancer efficacy of MKT 4 versus cisplatin and its chemomodulation by buthionine sulfoximine (BSO) in four different human ovarian carcinoma (OvCA) cell lines derived from both primary (A2780. OTN 14) and recurrent tumors (SKOV-3 and OV-MZ-1b) using an in vitro microplate ATP bioluminescence assay (ATP-TCA). Sensitivity against cisplatin was higher in A2780 and OTN 14 compared with MKT 4, whereas the opposite was found in SKOV-3 and OV-MZ-1b cells. In A2780, SKOV-3 and OV-MZ-1b, the cytotoxicity of both agents could be effectively improved by BSO with supraadditive effects observed for MKT 4 in all three cell lines. In OTN 14, however, BSO treatment failed to increase the cytotoxicity of both cisplatin and MKT 4. These results suggest antineoplastic activity of MKT 4 in cisplatin-sensitive and mainly in cisplatin-resistant OvCA cells which can be significantly modulated by BSO-mediated glutathione depletion. Since antineoplastic activity of both cisplatin and MKT-4 observed in OTN 14 could not be reversed by BSO, other mechanisms of drug resistance different from the glutathione redox cycle are likely to be important for both metal compounds.

Adenocarcinoma↗
PubMed1993

Titanocendichloride activity in cisplatin and doxorubicin-resistant human ovarian carcinoma cell lines.

The activity of a new organometallic compound, titanocendichloride, was evaluated in doxorubicin- and cisplatin-resistant human ovarian carcinoma cell lines in vitro. Titanocendichloride showed no cross resistance to doxorubicin in two multidrug resistant sublines of A2780. Furthermore, the cell line A2780 CP3, which is about 20-fold resistant to cisplatin was only 2.5-fold resistant to titanocendichloride, indicating a lack of cross resistance between the two metal compounds. These results were confirmed in vivo where titanocendichloride showed a much stronger inhibitory effect in cisplatin-resistant human ovarian carcinoma xenografts than cisplatin.

Animals↗
PubMed1992

Antitumor activity of treosulfan against human breast carcinomas.

Treosulfan (L-threitol-1,4-bismethanesulfonate, Ovastat) is a bifunctional alkylating agent that shows a formal structural similarity to busulfan and is applied clinically to patients suffering from ovarian cancer. The present study demonstrated the pronounced antitumor activity of this drug against three of five human breast carcinomas xenografted to athymic mice. It was shown that treosulfan is capable of inducing irreversible and complete remission of the heterotransplanted human breast carcinomas MDA-MB-436 and MX-1 within 14 days after drug application and of effecting growth inhibition by more than 90% in the MDA-MB-435S xenograft. In all three carcinomas, treosulfan caused more pronounced growth reduction than did equitoxic doses of the alkylator cyclophosphamide. Adriamycin, an intercalating cytostatic agent that is an important component of clinical nonhormonal chemotherapy of breast carcinomas, induced only partial remission of these three xenografts and inhibited the tumor growth by 80%-90% (MDA-MB-436, MX-1) and by 70%-80% (MDA-MB-435S), respectively. In the M 3 xenograft, treosulfan just led to a retardation and stagnation of tumor growth; it was again more effective than Adriamycin but was clearly less active than cyclophosphamide. The FM 2 breast carcinoma, finally, was the only xenograft whose growth was not influenced by treosulfan at doses up to that which was lethal to 50% of the treated mice (LD50 value). These results confirm that treosulfan is effective against human breast carcinomas. Because of this activity as well as the known low toxicity and good clinical compatibility of treosulfan, it should be considered for introduction into nonendocrine chemotherapeutic regimens against human breast carcinomas and investigation in clinical trials.

Animals↗
PubMed1986

[The simultaneous occurrence of chronic lymphatic leukemia with malignant tumors and the lymphatic reaction caused by malignant growths].

In 352 patients affected with chronic lymphatic leukemia (CLL) the authors simultaneously detected a solid second tumour 22 times (= 6.22%) (6 cancers of the prostrate, 5 cancers of the skin, 4 cancers of the uterus, 2 cancers of the stomach, 2 cancers of the lung, one case of rectal and mamma cancer each and one case of eye sarcoma). In one third of the cases the two malignomas were simultaneously detected, thus it was excluded that the second tumour was induced by the antimitotic treatment of the primary disease. In seven cases the solid tumour was identified after diagnosing CLL, without any cytostatic therapy having been made here before. In addition, a report is given on a patient showing symptoms of gastric cancer not radically removed and a lymphocytic reaction. Initially, the case was explained as gastric adenocancer with simultaneous CLL because even 5 years after surgical treatment there were 16-20 X 10(6)/l of leukocytes with 64% of lymphocytes in the peripheral blood and 85% of lympho-reticular cells in the bone marrow. Two years later, however, the blood picture was normal and remained to be unchanged further on. Thus, it seems that the healing of the gastric cancer has caused the lymphocytic reaction to have ceased. In addition, it should be noted that in 1974 the patient suffered from an epithelium after a scratch-mark on the nose tip, which was irradiated, however, without eliciting any lymphocytic reaction. The patient is still alive (June 1985).

Aged↗
PubMed1977

[Hepatogenic polyglobulinemias and polycythemias].

The authors distinguish three kinds of hepatogenous polyglobulia: Polycythaemia caused by Budd-Chiari syndrome, polycythaemia caused by a Mosse syndrome (cirrhosis without liver venous thrombosis) and polyglobulia caused by liver tumours. In all three cases the same mechanism is likely to induce polycythaemia or polyglobulia respectively. In addition to the three cases of the Mosse syndrome published in 1966, the present paper deals with three cases of Budd-Chiari syndrome. Twice the Budd-Chiari syndrome was followed by a polycythaemia, once a Budd-Chiari syndrome was developed in the course of a polycythaemia vera.

Adult↗
PubMed1975

[Association of chronic myelosis and cancer].

During the period between 1948-1963 a total of 3,200 tumor patients were treated in the First and Second Medical Clinics of Tg.-Mures. In these tumor patients as well as the skin cancer patients who were treated with radiotherapy the authors found in 1.5% of the patients a leukocytosis of more than 20,000. In the last ten years (1964-1974), however, in the Second Medical Clinic only, 5% of 516 tumor patients showed a leukocytosis exceeding 20,000. In the first group of patients (3,200 cases) 0.03% showed more than 50,000 leukocytes, in the other group of 516 patients 0.2% showed more than 50,000 leukocytes. These values point towards a leukemoid reaction. A shift to the left to the myelocytes or beyond in the blood picture was found in the Second Medical Clinic in 10% of patients with carcinoma during the year of 1974. In 6% of the cases erythroblasts in the peripheral blood were seen, too. This deviation occurred often independent of the total number of leukocytes and was of a temporary nature. During the same time (1949-1974) 128 patients with chronic myeloid leukemia were treated in both departments as in-patients. 6 cases (i.e., 4.6%) had a chronic myelosis simultaneous with carcinoma, in one case together with an osteosarcoma. The diagnosis was confirmed in all cases by autopsy.

Autopsy↗