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Biomedical subjects

C Unger

Publications and source records attributed to C Unger.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cartilage-specific autoimmunity in rheumatoid arthritis: characterization of a triple helical B cell epitope in the integrin-binding-domain of collagen type II.

Cartilage-specific proteins are considered potential autoantigens that could continuously fuel autoimmune responses directed to the joints in rheumatoid arthritis (RA). Using recombinant chimeric collagen type II we have identified one major type II collagen (CII) epitope (denoted U1) recognized by RA sera. The U1 epitope is a triple helical structure formed by 11 amino acids (triple helical position 494-504) and colocalizes with the recently described alpha1beta1/alpha2beta1 integrin binding site. It is a major epitope, found in 14/22 RA sera positive for antibodies to CII. One individual could be followed for a long time and the results showed that IgG antibodies specific for the U1 epitope were maintained along the chronic disease course but suppressed during periods of cyclosporin A and anti-CD4 treatment. We also found that the U1 epitope was recognized in rats susceptible to collagen-induced arthritis. A monoclonal autoantibody (mAb 126.30) was raised from DA rats, which bound the same epitope. The antibodies bound the cartilage in vivo showing that the epitope is exposed to the immune system for immune complex formation in the intact joint.

Animals↗
PubMed2001

Suppressed expression of nicotinic acetylcholine receptors by nanomolar beta-amyloid peptides in PC12 cells.

A line of evidence has shown that a link between the common pathological features of beta-amyloid peptide (Abeta) deposition and cholinergic degeneration observed in Alzheimer's disease (AD) may exist, however, no experimental evidence has shown that exposure to Abeta can decrease expression of nicotinic acetylcholine receptors (nAChRs), which have been shown to play roles in brain cognitive functions. Here, we report that treatment with Abeta1-40 and Abeta25-35 at nanomolar concentrations significantly decreased the [3H]epibatidine and [125I]alpha-bungarotoxin binding sites, the protein and mRNA levels of nAChR alpha3, alpha7 and beta2 subunits in PC12 cells. Abeta1-40 and Abeta25-35 at the concentrations used in the treatment study neither bound to nAChRs nor induced apoptosis, but significantly inhibited the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5,diphenyl tetrazolium bromide) reduction. These data suggest that the decreased biosynthesis of nAChRs induced by Abeta may be attributable partially to perturbances of some intracellular signal transduction pathways. The results presented in this study lead to a hypothesis that Abeta can degenerate nAChRs early in the course of AD before the formation of abundant Abeta fibrils.

Acetylcholine↗
PubMed2001

Excellent response to gemcitabine in a massively pre-treated woman with extensive cutaneous involvement after recurrence of breast cancer.

A 50-year-old woman presented with local relapse of breast cancer 6 years after partial mastectomy. Relapse was accompanied by extended skin induration due to tumor cell embolization of dermal lymphatics. During the following years the patient was exposed to 11 different anti-tumor regimens including 13 cytotoxic drugs (including alkylating agents, antitumor antibiotics, vinca alcaloids, epipodophyllotoxins, and taxanes), 4 anti-hormonal, and 2 immunologic attempts. Paclitaxel achieved a prolonged local improvement for some 7 months, but further various treatments were ineffective. At that time gemcitabine therapy was initiated and tumor infiltration of the skin was visibly diminished only 2 weeks later. After that tumor regressed further for 5 months and remained stable with continued doses of gemcitabine during much of the woman's last year. The patient died of acute myeloid leukemia (AML) 4 years after the local recurrence of breast cancer. Since multiple treatments using a plethora of aggressive cytotoxic drugs may render several classes of chemotherapy agents ineffective due to cross-resistance, it seems advisable to select mild agents that are not subject to multidrug resistance mechanisms and display a unique mode of action as demonstrated in this case by gemcitabine.

Antimetabolites, Antineoplastic↗
PubMed2001

Differences in the intracellular distribution of acid-sensitive doxorubicin-protein conjugates in comparison to free and liposomal formulated doxorubicin as shown by confocal microscopy.

PURPOSE: To investigate differences in the cellular uptake and intracellular distribution of protein-bound doxorubicin in comparison to free doxorubicin and a liposomal formulation (CAELYX) METHODS: LXFL 529 lung carcinoma cells were incubated with an acid-sensitive transferrin and albumin conjugate of doxorubicin, a stable albumin doxorubicin conjugate, and free and liposomal doxorubicin for up to 24 h. The uptake of doxorubicin was detected with confocal laser scanning microscopy (CLSM). To investigate the intracellular localization of the anticancer drug, lysosomes, Golgi apparatus, and mitochondria were also stained by various organelle-specific fluorescent markers. In vitro efficacy of the doxorubicin derivatives was examined with the BrdU incorporation assay. RESULTS: The acid-sensitive albumin and transferrin doxorubicin conjugates showed enhanced cytotoxicity in comparison to liposomal doxorubicin, whereas the stable albumin-doxorubicin conjugate showed only marginal activity. Of all compounds tested, doxorubicin showed the highest cytotoxicity. CLSM studies with specific markers for lysosomes, mitochondria, and the Golgi apparatus demonstrated that protein-bound doxorubicin or liberated doxorubicin was accumulated in the mitochondria and Golgi compartments, but not in the lysosomes after 24 h. Free doxorubicin showed a time-dependent intracellular shift from the nucleus to the mitochondria and Golgi apparatus. Fluorescence resulting from incubation with CAELYX was primarily detected in the nucleus. CONCLUSIONS: Our results indicate that other organelles in addition to the cell nucleus are important sites of accumulation and interaction for protein-bound doxorubicin or intracellularly released doxorubicin as well as for free doxorubicin.

Antineoplastic Agents↗
PubMed2001

Double-blind randomised placebo-controlled phase III study of an E. coli extract plus 5-fluorouracil versus 5-fluorouracil in patients with advanced colorectal cancer.

The primary aim of this study was to evaluate the toxicity (mucositis, diarrhea and leucopenia) of a therapy with 5-fluorouracil (CAS 51-21-8; 5-FU) plus an E. coli extract (LC-Extract, Laves coli extract, Colibiogen inject, cell-free soluble fraction from lysed E. coli, Laves strain) in comparison with 5-FU plus placebo. Secondary endpoints included general toxicity, response rate according to WHO, survival time and quality of life. 164 patients with advanced colorectal cancer were enrolled in this randomised, placebo-controlled, double-blind, multicenter phase III study. The treatment consisted of 0.167 ml/kg/d LC-Extract or placebo followed by 500-750 mg/m2/d 5-FU on five consecutive days, repeated every three weeks for up to six treatment cycles. 158 (77 verum, 81 placebo) patients were evaluable for toxicity, 144 (72 verum, 72 placebo) evaluable for response. The therapy with LC-Extract was well tolerated. Adverse events that occurred during the study were mainly judged as 5-FU- or tumor-related. Toxicity from treatment with 600 mg/m2/d 5-FU in both treatment groups was very low. After treatment with 750 mg/m2/d 5-FU patients in the placebo-group experienced a higher CTC toxicity than in the LC-Extract groups. Remission rate and survival time showed a slight trend in favour of LC-Extract. These results suggest a positive benefit-risk ratio of the additional application of LC-Extract to 5-FU in the treatment of advanced colorectal cancer especially for administration of high doses of 5-FU.

Adolescent↗
PubMed2001

Palliative chemotherapy in pretreated patients with advanced cancer: oral trofosfamide is effective in ovarian carcinoma.

Thirty-four patients with advanced cancer of various origins and documented disease progression were treated with continuous daily doses of 50-150 mg of oral trofosfamide (TRO). Of 31 evaluable patients, 5 responded to this treatment (1 complete remission and 4 partial remissions) and 12 patients had stable disease. Four of 9 patients with advanced ovarian cancer resistant to platinum-containing regimens and paclitaxel responded to oral TRO. The median treatment duration was 26 weeks for responders and 6 weeks for nonresponders, with cumulative doses of up to 46.000 mg TRO. Response duration was 11-47 weeks. No significant side effects were observed. Oral TRO given in the outpatient setting seems to be an attractive therapeutic option for heavily pretreated cancer patients, and it has remarkable antitumor effects in patients with ovarian cancer.

Adult↗
PubMed2001

Identification of conformation-dependent epitopes and V gene selection in the B cell response to type II collagen in the DA rat.

Collagen-induced arthritis (CIA) is a widely used model for rheumatoid arthritis. Induction of CIA in rats using rat type II collagen (CII) results in a chronic arthritis in which anti-CII antibodies are believed to play a pathogenic role. In this study, we analyzed the epitope selection and V gene usage in the anti-CII response in the DA rat. A panel of CII-reactive B cell hybridomas was established from the draining lymph nodes 11 days after immunization. All of the CII-specific antibodies bound cartilage in vivo, showing that these are true autoantibodies. These antibodies were all IgG and specific for several distinct triple helical epitopes on CII. Interestingly, the major epitope, recognized by four different antibodies, was identical with the major B cell epitope in the mouse CII located at position 359--369 (denoted as C1(III)). The Q52 and PC7183 V(H) gene families encoded 12 out of 14 sequenced heavy chains. There was a relatively more heterogeneous usage of V(L) genes as the antibodies were encoded by four different V(kappa) families (V(kappa)1, V(kappa)2, V(kappa)12/13 and V(kappa)RF). As in the mouse, some of the V genes used showed germline characteristics. We conclude that the immune response in the rat shares epitope specificity and a constrained V gene repertoire with the mouse. However, the V genes used for recognition of the closely related collagen structures differed considerably between mouse and rat, indicating an influence of the species-specific variation in the V gene repertoire.

Amino Acid Sequence↗
PubMed2001

Activity of pemetrexed (ALIMTA, multitargeted antifolate, LY231514) in metastatic breast cancer patients previously treated with an anthracycline and a taxane: an interim analysis.

As many breast cancer patients receive adjuvant chemotherapy using anthracyclines or anthracenediones and taxanes, more therapeutic options are needed for subsequent lines of therapy. Pemetrexed (ALIMTA, multitargeted antifolate, LY231514) is a novel antifolate that inhibits several enzymes in the de novo pathways of pyrimidine and purine biosynthesis. This paper reports on a subset analysis of a phase II clinical trial of pemetrexed in heavily pretreated metastatic breast cancer (MBC) patients. Patients were required to have received prior first-line anthracycline therapy for metastatic disease. Prior adjuvant chemotherapy and prior taxanes were allowed. A substantial subset of the study population (31 of 72 patients, 43%) had also received a taxane in the metastatic setting. All patients were treated with pemetrexed, 600 mg/m2 by intravenous infusion, once every 21 days. In the study subset, 23 of 31 (74%) patients were anthracyclines failures (progression > 30 days following treatment), and eight (26%) patients were anthracyclines refractory (progression during or < or = 30 days of treatment). The median age was 55 years (range, 30-75 years) and the median World Health Organization performance status was 0. Metastases were present in the liver (61%), lung (29%), bone (6%), and soft tissue (19%). The overall response rate for this subset was 26%, with one complete response, seven partial responses, and 13 (42%) patients with stable disease. The median duration of response was 5.4 months and median survival was 12.8 months. Pemetrexed was well tolerated by patients in the study. This post hoc analysis suggests promising activity in MBC patients previously treated with both anthracyclines and taxanes. An ongoing trial is prospectively evaluating activity in this same population.

Adult↗
PubMed2000

Effect of nucleoside analogues and oligonucleotides on hydrolysis of liposomal phospholipids.

The hydrolysis of the bilayer forming phospholipids resulting first of all in lysophospholipids and fatty acids is one limiting factor determining the shelf-life of liposomes. In several studies the influence of pH, buffer, lipid composition and other parameters on the hydrolysis of phospholipids have been demonstrated, but the influence of drugs has not yet been investigated systematically. In this study the influence of nucleoside analogues, especially 2', 2'-difluoro 2'-deoxycytidine (gemcitabine, dFdC) on the degradation of phospholipids was elucidated in more detail. It could be demonstrated that the interaction of dFdC with phospholipid bilayers promotes the hydrolysis of phospholipids in a concentration-dependent manner. Obviously two parts of the molecule, the amino group bound to the pyrimidine moiety and the 2', 2'-difluoro-2'-deoxyribose, seem to be responsible for the forced phospholipid hydrolysis. The dFdC-induced hydrolysis of phospholipids was influenced by pH, buffer, lipid composition and different anions. Optimization of the above parameters resulted in prolonged shelf-life of dFdC liposome dispersions, which is an important prerequisite for clinical practice.

Anions↗
PubMed2000

Effects of PTK787/ZK 222584, a specific inhibitor of vascular endothelial growth factor receptor tyrosine kinases, on primary tumor, metastasis, vessel density, and blood flow in a murine renal cell carcinoma model.

Antiangiogenic therapy is a promising new strategy to inhibit tumor growth and formation of metastases. Vascular endothelial growth factor (VEGF) and its receptors, VEGF-receptor 1 (VEGF-R1; FLT-1) and VEGF-R2 (KDR), have been shown to play a major role in tumor angiogenesis. PTK787/ZK 222584, a specific inhibitor of both VEGF-receptor tyrosine kinases, was investigated for its antitumoral and antiangiogenic activity in a murine renal cell carcinoma model. After intrarenal application of the renal carcinoma cells, mice develop a primary tumor and metastases to the lung and to the abdominal lymph nodes. Daily oral therapy with PTK787/ZK 222584 at a dose of 50 mg/kg resulted in a significant decrease of 61 and 67% in primary tumors after 14 and 21 days, respectively. The occurrence of lung metastases was significantly inhibited at both time points (98% reduction and 78% reduction, respectively). After 14 days, no lymph node metastases developed in the PTK787/ZK 222584-treated group, whereas after 21 days of treatment, the lymph node metastases were reduced by 87%. Vessel density in tumor tissues, detected by immunohistochemistry with an anti-CD31 antibody, was significantly decreased by PTK787/ZK 222584. Using color Doppler imaging ultrasound, significant changes in blood flow in the tumor feeding renal artery were found under treatment with PTK787/ZK 222584. Blood flow changes correlated with changes in vessel density but not with tumor volume. The compound was well tolerated in all in vivo experiments and had no significant effects on body weight or general well-being of the animals. This was in contrast to the animals treated with the antiangiogenic agent TNP-470. s.c. therapy with 30 mg/kg TNP-470 every other day had to be discontinued after 13 days because of animal weight loss (>20%) and ataxia. These results demonstrate that PTK787/ZK 222584 is a potent inhibitor of tumor growth, metastases formation, and tumor vascularization in murine renal cell carcinoma. Furthermore, we have been able to demonstrate that color Doppler imaging ultrasound can be used to measure blood flow to a tumor and that flow correlates with vessel density. Thus, this may be a valuable noninvasive method for monitoring the effects of antiangiogenic agents such as PTK787/ZK 222584 on tumor vasculature.

Angiogenesis Inhibitors↗
PubMed2000

Targeting of endothelial KDR receptors with 3G2 immunoliposomes in vitro.

Immunoliposomes (IL) containing anti-angiogenic drugs directed selectively to the easily accessible kinase insert domain containing receptor (KDR) vascular endothelial growth factor (VEGF), which is predominantly expressed on tumour vessels are a promising tool to inhibit tumour angiogenesis. To explore this strategy, we have prepared fluorescent-labelled IL presenting antibodies against the KDR receptor (3G2) on their surface. 3G2-IL were composed of egg phosphatidylcholine and cholesterol (6:4), containing 2 mol% of the new thiol reactive linker lipid O-(3-cholesteryloxycarbonyl)propionyl-O'-m-maleimido-benzoyl tetraethylene glycol. Specific binding of 3G2-IL to immobilised recombinant KDR was used to show the maintenance of sufficient immunoreactivity of 3G2 antibodies upon the coupling procedure. 3G2-IL bound to Chinese hamster ovarian (CHO) cells stably transfected to overexpress KDR to a five times higher amount as compared to mock-transfected CHO cells. Subsequently, specific binding of 3G2-IL to KDR could also be demonstrated on KDR expressing cells, human umbilical vein endothelial cells and human microvascular endothelial cells, whereas only low binding of 3G2-IL to NIH-3T3 mouse fibroblast cells, which do not express KDR, was found. The binding of 3G2-IL to KDR receptors could not be blocked by VEGF, suggesting that the binding site for VEGF is not identical with the epitope recognised by 3G2. We could demonstrate that 3G2-IL is able to bind in vitro even in the presence of high levels of VEGF.

3T3 Cells↗
PubMed2000

In vitro and in vivo efficacy of acid-sensitive transferrin and albumin doxorubicin conjugates in a human xenograft panel and in the MDA-MB-435 mamma carcinoma model.

Acid-sensitive transferrin and albumin conjugates with doxorubicin have recently been developed with the aim of circumventing the systemic toxicity and improving the therapeutic efficacy of this anticancer agent. The in vitro activity of two acid-sensitive transferrin and albumin doxorubicin conjugates and free doxorubicin was evaluated in twelve human tumour xenografts using a clonogenic assay. The inhibitory effects and the activity profile of the conjugates was, in general, comparable to that of doxorubicin (mean IC(70) -value for doxorubicin approximately 0.1 microM and 0.1 - 0.4 microM for the conjugates). Subsequently, the efficacy of an acid-sensitive transferrin and albumin doxorubicin conjugate, which both incorporated a phenylacetyl hydrazone bond as a predetermined breaking point, was evaluated in the xenograft mamma carcinoma model MDA-MB-435 in comparison to free doxorubicin (dose, i.v.: 2 x 4, 8 and 12 mg/kg). The conjugates showed significantly reduced toxicity (reduced lethality and body weight loss) with a concomitantly stable or slightly improved antitumour activity compared to free doxorubicin. At the dose of 12 mg/kg mortality was unacceptably high in the doxorubicin treated group ( approximately 80%); in contrast, no mortality was observed with the conjugate treated animals with body weight loss < 10 %. In a further experiment, therapy with the acid-sensitive doxorubicin albumin conjugate at 3 x 12 mg/kg in the MDA-MB-435 model resulted in a significantly improved antitumour activity over free doxorubicin at its optimal dose of 2 x 8 mg/kg. In conclusion, acid-sensitive transferrin and albumin doxorubicin conjugates can be administered at higher doses than free doxorubicin in nude mice models with a concomitant improvement in antitumour activity. Interestingly, there is no pronounced difference between identically constructed transferrin and albumin doxorubicin conjugates with regard to in vitro or in vivo efficacy.

Animals↗
PubMed1999

Synthesis and PLA2-inhibitory properties of 2(R)-acetamido-alkylphosphomethanols with a variable aggregate anchor.

Acylamino inhibitors of 14 kDa-PLA2 were synthesized which differ in the moiety that is not bound into the enzyme's active site but immersed in the lipid aggregate when a ternary inhibitory complex is formed. Our results indicate that this part of the inhibitors does not significantly influence inhibitory properties as long the amphiphilic character is retained. So, inhibitory and biophysical properties should be variable independently.

Acetamides↗
PubMed1999

Vascular endothelial growth factor in the sera and effusions of patients with malignant and nonmalignant disease.

BACKGROUND: Clinical data clearly indicate a correlation between tumor neovascularization, aggressiveness of tumor growth, and metastatic spread. One of the key factors capable of stimulating tumor angiogenesis is vascular endothelial growth factor (VEGF). Using an immunoassay for VEGF, we assessed the levels of soluble VEGF in the sera and effusions of patients with malignant and nonmalignant disease as well as in the sera of healthy controls. METHODS: Using a sandwich enzyme-linked immunoadsorbent assay, the concentration of VEGF was measured in serum specimens (n=445) and effusions (n=56) collected from a total of 212 patients with various types of cancer, 88 patients with nonmalignant disease, and 145 healthy individuals. RESULTS: Low and rather stable levels of VEGF were detected in the serum of healthy individuals (median, 294 pg/mL; range, 30-1752 pg/mL; 95th percentile, 883 pg/mL). Compared with healthy individuals, serum levels in patients with acute infections were elevated (P=0.03), whereas patients with chronic cirrhosis had lower serum VEGF levels. Among patients with various types of neoplasia, VEGF serum levels in patients with ovarian or gastrointestinal carcinoma were significantly higher than in healthy individuals. Moreover, VEGF concentrations in sera from patients with metastatic disease were higher than in sera from patients with localized tumors. Maximum serum concentrations of VEGF (median, 1022 pg/mL; range, 349-7821 pg/mL) were found in patients with metastatic ovarian carcinoma. Median VEGF levels (and ranges) in malignant effusions were up to 10-fold higher than in matched serum samples: 5528 pg/mL (468-49269 pg/mL) in ovarian carcinoma, 885 pg/mL (77-14,337 pg/mL) in breast carcinoma, and 813 pg/mL (372-18,331 pg/mL) in gastrointestinal carcinoma. In contrast, ascitic fluid from patients with cirrhosis contained only 303 pg/mL (median, range 116-676 pg/mL) of VEGF, corresponding to the low serum levels in this patient group. CONCLUSIONS: Depending on the tumor type, elevated levels of VEGF are detectable in the serum of only 0-20% of patients with localized cancer but in 11-65% of patients with metastatic cancer. Of cytology-proven malignant ascites or peritoneal exudates from various malignancies, 46-96% show VEGF levels above the upper limit (95th percentile, 676 pg/mL) of nonmalignant ascites. Maximum VEGF concentrations in malignant effusions indicate abundant local release of VEGF within the pleural or peritoneal cavity. These results suggest that VEGF might play an important role in tumor progression and the formation of malignant effusions. Further studies are warranted to determine the clinical value of soluble VEGF as a tumor marker, a prognostic factor, and a surrogate indicator of tumor angiogenesis.

Adult↗
PubMed1999

Clinical activity and benefit of irinotecan (CPT-11) in patients with colorectal cancer truly resistant to 5-fluorouracil (5-FU).

The aim of this prospective study was to assess the efficacy, clinical benefit and safety of CPT-11 (irinotecan) in patients with stringently-defined 5-fluorouracil-resistant metastatic colorectal cancer (CRC). 107 patients with documented progression of metastatic CRC during 5-FU were treated with CPT-11 350 mg/m2 once every 3 weeks in a multicentre phase II study. Tumour response and toxicity were assessed using WHO criteria. Changes in performance status (PS), weight and pain were also measured. The WHO response rate was 13/95 (13.7%, 95% CI 7.5% to 22.3%) eligible patients with a median duration of response of 8.5 months (37 weeks, range: 18-53+). There was also a high rate of disease stabilisation (44.2%) with a median duration of 4.8 months. The probability of being free of progression at 4 months was 50%. Median survival from first administration of CPT-11 was 10.4 months or 45 weeks (range: 3-66+ weeks). There was weight stabilisation or gain in 81% (73/90) of patients, a favourable outcome in PS in 91% (82/90) (improvement of WHO PS 2 or stabilisation of PS 0-1), and pain relief in 54% (26/48). There were no toxic deaths. Neutropenia was short-lasting and non-cumulative. Diarrhoea grade > or = 3 occurred in 7% of cycles and 28/107 (26%) of patients. CPT-11 350 mg/m2 once every 3 weeks has an encouraging degree of activity in progressive metastatic CRC truly resistant to 5-FU with a relatively high rate of tumour growth control translated into clinical benefit. The toxicity profile of CPT-11 is becoming better understood and has been considerably improved.

Adult↗