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W Ebert

Publications and source records attributed to W Ebert.

At least 37 records · Page 2Linked to original sources

Differential secretion of cathepsins B and L from normal and tumor human lung cells stimulated by 12(S)-hydroxy-eicosatetraenoic acid.

Cathepsins B and L play roles in intracellular and extracellular proteolysis in normal and malignant processes. A directed extracellular proteolysis by regulated secretion could facilitate the process of invasion. We have therefore investigated the effect of the physiological signal mediator 12(S)-hydroxy-eicosatetraenoic acid on the release of cathepsins B and L in normal and malignant human lung cells. Quantitative determinations of cathepsin activities were done by flow cytometry and spectrofluorometry using synthetic dipeptidyl substrates coupled to fluorogens. Most interestingly, a difference in the secretion of cathepsins B and L was found: only release of active cathepsin B was detected. The effect was specific for 12(S)-hydroxy-eicosatetraenoic acid, 12(R)-hydroxy-eicosatetraenoic acid, and 5(S)-hydroxy-eicosatetraenoic acid were ineffective. The response was immediate but a substantial amount of nonreleasable activity remained cell bound. Alveolar macrophages, Wi-38 fibroblasts, and tumor cells derived from large cell carcinomas and adenocarcinomas were sensitive to 12(S)-hydroxy-eicosatetraenoic acid, but cells from undifferentiated squamous cell carcinomas were not. Sensitivity did not parallel malignancy but more likely the degree of differentiation of cells. The investigated tumor cell lines showed no detectable endogenous 12-lipoxy-genase activity to synthesize 12(S)-hydroxy-eicosatetraenoic acid from arachidonate; therefore, we assume a paracrine mechanism for 12(S)-hydroxy-eicosatetraenoic acid action. Protein kinase C alpha, a key enzyme involved in 12(S)-hydroxy-eicosatetraenoic acid-elicited responses, was expressed in all sensitive tumor cells, but insignificantly in a sensitive normal cell line and an insensitive tumor cell line. From our experiments we propose two separate intracellular pools of active cathepsin B: an unreleasable, lysosomal fraction and a fraction available for regulated secretion. Different processing and sorting mechanisms may be responsible for the generation of these cathepsin B-fractions in these pools.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

Paramagnetic metalloporphyrins: infarct avid contrast agents for diagnosis of acute myocardial infarction by MRI.

In previous experiments in tumors we demonstrated that metalloporphyrins are particularly avid for nonviable tumor components. This study was performed to find out whether these agents can be used as MRI contrast agents for the visualization of acute myocardial infarction (MI). A total of 44 rats, 6 normal controls and 38 with occlusive MI (2-24 h old), were used. Gadolinium mesoporphyrin (Gd-MP) or manganese tetraphenylporphyrin (Mn-TPP) was intravenously injected at doses of 0.1, 0.05, and 0.01 mmol/kg. Three to 24 h after injection, axial and coronal T1-weighted (TR/TE 300/15 ms) spin-echo MR images were obtained before and after killing the animals and correlated with triphenyl tetrazolium chloride (TTC) histochemical preparations. The Gd-MP content in infarcted and noninfarcted myocardium was measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). MRI without contrast media could not discern the MI. However, 3-24 h after injection of either Gd-MP or Mn-TPP, the infarcted area was positively stained on MR images. This area matched well with the negatively TTC-stained area on the heart slices (r = 0.97). The contrast ratios between the infarcted necrotic myocardium and the noninfarcted regions varied from 150 to 300% depending on the type of agents and doses used. Neither false-positive nor false-negative findings were encountered. The metalloporphyrin concentration was more than 10 times higher in the infarcted than in the noninfarcted heart. Metalloporphyrins appear to be promising MRI contrast agents for detection and quantification of necrosis in MI. These preclinical results may open new perspectives in cardiac imaging.

Animals↗

Do neuron-specific enolase levels discriminate between small-cell lung cancer and mediastinal tumors?

The capacity of pretherapeutically assessed neuron-specific enolase (NSE) to differentiate between small cell lung cancer (SCLC) and mediastinal tumors was investigated retrospectively in a series of 320 patients. NSE was found to be increased in 95/130 (73.1%) patients with SCLC, in 4/62 (6.5%) patients with Hodgkin's disease, in 10/58 (17.2%) patients with non-Hodgkin's lymphoma, in 5/16 (31.3%) patients with teratoma, and in 6/54 (11.1%) patients with thymoma. The cut-off value, defined as the 95% percentile of a reference population suffering from benign pulmonary disorders (n = 192), was set at 13.8 ng/ml. When this discrimination level was increased to 26.4 ng/ml, which corresponds to a 95% specificity versus the total group with mediastinal tumors, SCLC was recognized with a detection rate of only 49.2%. In conclusion, increased NSE concentrations in a patient with a hilar mass and/or mediastinal widening on X-ray are not always diagnostic of SCLC due to the high rate of elevated NSE values associated with mediastinal tumors. However, in a patient who presents with a hilar mass and a high NSE level, bronchoscopy is always indicated to obtain adequate specimens for histology in order to plan an appropriate therapeutic regimen.

Adolescent↗

Localization of metalloporphyrin-induced "specific" enhancement in experimental liver tumors: comparison of magnetic resonance imaging, microangiographic, and histologic findings.

RATIONALE AND OBJECTIVES: We investigated the tumor specificity of gadolinium mesoporphyrin (Gd-MP) and manganese tetraphenylporphyrin (Mn-TPP) as magnetic resonance (MR) imaging contrast agents. METHODS: Fifteen rats with multiple hepatocellular carcinomas and eight rats with implanted Novikoff hepatomas were given intravenous injections of either Gd-MP or Mn-TPP at 0.05 mmol/kg, which was compared with nonspecific gadopentetate dimeglumine (0.3 mmol/kg). T1-weighted spin-echo images were obtained before and up to 48 hr after injection and compared with corresponding microangiograms and histologic specimens. The relative enhancement of organs and tumors was plotted as a function of time. RESULTS: Initially, both metalloporphyrins behaved as nonspecific agents, similar to gadopentetate dimeglumine, and enhanced the tumor by perfusion and diffusion. However, metalloporphyrins, but not gadopentetate dimeglumine, caused a delayed (> or = 3 hr) enhancement in some compartments of certain lesions. The MR imaging-microangiography-histology matching technique revealed that those compartments were actually nonviable components, including necrosis (n = 10), thrombosis (n = 7), and cystic secretion (n = 3), but not viable tumor tissue. CONCLUSION: Metalloporphyrins did not prove to be tumor specific. However, the observed affinity for nonviable tissue has elicited other potential applications for these agents.

Angiography↗

Assessment of cathepsin L activity by use of the inhibitor CA-074 compared to cathepsin B activity in human lung tumor tissue.

In a series of pairs of lung tumor tissue and non-tumor lung parenchyma from 50 patients, the activity of cathepsin L was measured with Z-Phe-Arg-AMC using the inhibitor CA-074 to delimitate from cathepsin B activity also present in the tissue extracts. Cathepsin B was assessed in the same samples with its specific substrate Z-Arg-Arg-AMC. It was found that in tumor tissue the median activities of cathepsin L and cathepsin B were increased 1.6-fold and 4.9-fold, respectively. The levels of activity of both enzymes did not correlate with TNM stages nor with cell differentiation of bronchial carcinomas. Cathepsin L activity was found to be insignificantly higher in adenocarcinoma compared to squamous cell carcinoma, while cathepsin B activity did not vary across the histologies. The activities of both enzymes were low in pulmonary carcinoids, which are known to be low-grade malignant neoplasms. The amount of cathepsin B activity exceeded by far that of cathepsin L activity as proven by measurement with Z-Phe-Arg-AMC in the presence of the inhibitor Z-Phe-Phe-CHN2:95-98% of cathepsin B activity vs 2-5% of cathepsin L activity were determined. By SDS-PAGE separation and immunoblot analysis, it could be demonstrated that significant amount of cathepsin L is complexed with the cysteine proteinase inhibitor kininogen. This explains the rather low cathepsin L activity values in the tissue extracts.

Adenocarcinoma↗

Quantification of intracellular cathepsin activities in human lung tumor cell lines by flow cytometry.

The cysteine proteases cathepsin B and cathepsin L are very likely involved in invasive processes of normal and malignant cells, they become relevant for a number of diseases and are possibly prognostic markers for the outcome of human lung cancer. Therefore, we have determined activities of these related enzymes in cells and in cell extracts of human lung carcinoma cell lines of different cathepsin composition by flow cytometry and by spectrophotometry, respectively. To this end we applied the synthetic dipeptidyl substrates benzoxycarbonyl-arginyl-arginine- and benzoxycarbonyl-phenyl-arginine- coupled to 4-methoxy-beta-naphthylamide, aminomethyl-coumarine or rhodamine R110. The apparent enzymatic activities were differentially defined by protease inhibitors, particularly E-64 and CA-074. Independent of the dipeptidyl-composition more than 99 per cent of the apparent activity was due to cathepsin B when 4-methoxy-beta-naphthylamide or aminomethylcoumarine were the leaving groups. The 4-methoxy-beta-naphthylamide precipitate used for detection of cell associated activities revealed a wide spectrum of excitation to fluorescence thwarting the application of other possible fluorescent tags. Therefore, its application is restricted to uniparametric fluorescence investigations. Both dipeptidylgroups coupled to rhodamine R110 were promiscuous: only 25 to 30% of the apparent activity were due to cathepsin B; the predominant activity came from cathepsin L, irrespective whether intracellular or activities of cellular extracts were analyzed. However, rhodamine R110-coupled substrates open the way for multiparametric fluorescent analysis of cathepsins B and L containing cells if appropriate inhibitors for specification of the enzymatic activities are additionally applied. In very contrast to 4-methoxy-beta-naphthylamide, which causes irreparable damage to the cells, the rhodamine substrates permit studies with living cells and live cell sorting.

2-Naphthylamine↗

CYFRA 21-1--clinical applications and analytical requirements.

CYFRA 21-1 has proved to be a useful marker for non-small-cell lung cancer (NSCLC), which is the major form of lung cancer. Its most effective application is in monitoring. CYFRA 21-1 provides diagnostic information about the success of primary surgery, the response to chemotherapy and the detection of relapse. It is also an independent prognostic factor. The diagnostic potential may not be fully used because decision-making is currently based on group reference ranges. It seems useful to carry out systematic studies to investigate if the application can be improved and extended by using individual reference ranges for decision-making. In contrast to most of the other tumour markers the comparability of the commercial CYFRA 21-1- assays currently available on the market is good. The high degree of comparability should be maintained by international standardization. The analytical performance of the currently available commercial CYFRA 21-1 tests meets requirements derived from its current clinical applications. However, there are no data available about the analytical performance under field conditions. CYFRA 21-1, an established tumour marker for lung cancer, should be included in external quality assurance schemes.

Biomarkers, Tumor↗

Elastinolytic activity of alveolar macrophages in smoking-associated pulmonary emphysema.

Current concepts of pathomechanisms leading to acquired emphysema suggest that alveolar macrophages (AM) activated by cigarette smoking may cause an elastase/antielastase imbalance localized to the microenvironment formed by phagocytes and lung tissue. A functional cell assay was used to evaluate the cell-associated elastinolytic activity of AM. AM were obtained by bronchoalveolar lavage from patients with emphysema and from patients with non obstructive chronic pulmonary diseases (non-COPD) and cultured under serum-free conditions in direct contact with 3H-labeled elastin particles. Elastinolytic activity was calculated from the released radioactivity in culture supernatants and expressed as micrograms of 3H-elastin degraded x 10(-5) AM x 72 h-1. AM of patients with emphysema had significantly higher elastinolytic activity compared to that of non-COPD patients (median: 10.8 versus 4.1 micrograms; P < 0.01). Further differentiation of patients revealed the lowest median activity in sarcoidosis (2.3 micrograms). In respect to smoking habits there was a major difference between smokers with emphysema degraded more than twice the amount of elastin than smokers in the non-COPD group (median:11 versus 3.9 micrograms, P = 0.01). From these data we conclude that AM-derived elsatinolytic proteases may be involved in the destruction of lung elastin, which is thought to be the key event occurring in the pathogenesis of pulmonary emphysema.

Adult↗

Cathepsin B activity in human lung tumor cell lines: ultrastructural localization, pH sensitivity, and inhibitor status at the cellular level.

We investigated the appearance and activity of the cysteine proteinase cathepsin B and its physiological inhibitors, stefins A and B, at the cellular level in human tumor cell lines HS-24, derived from a primary lung tumor (squamous cell), and SB-3, derived from a metastasis (lung adenocarcinoma). In addition to cathepsin B, these tumor cells also expressed the immunologically and functionally related cathepsin L, but not cathepsin H. Stefin A was found in HS-24 but not in SB-3 cells; stefin B was found in both cell types. Using a specific fluorogenic cytochemical assay, the intracellular activity of the enzyme was localized and quantified. Thus, the cellular cathepsin B kinetics for the synthetic substrates Z-Arg-Arg-4M beta NA and Z-Val-Lys-Lys-Arg-4M beta NA, its pH dependence and inhibition by E64, stefins A and B, and cystatin C could be determined. From these measurements it appeared that the enzyme exhibited different cleavage rates for these substrates in the different cell types, showed considerable cleavage activity at neutral pH, which was stable under these conditions for extended time periods, and was highly sensitive to the inhibitors E64 and cystatin C but was considerably less sensitive to stefins, particularly stefin A. By conventional light microscopy, confocal laser scanning microscopy, and electron microscopy the enzymatic activity was localized in lysosomes, as expected, but also in the endoplasmic reticulum, nuclear membrane, and plasma membrane. The endoplasmic reticulum is a site at which only pre-mature enzyme forms exist, which are usually not active. The appearance of enzymatic activity at the plasma membrane confirms earlier biochemical and immunofluorescence microscopic investigations. The different sites of localization within the cells make it likely that different forms of the enzyme are expressed simultaneously, which follow alternate ways of processing and sorting. Taken together, the results support an involvement of the enzyme under extracellular conditions in degradative processes.

Amino Acid Sequence↗

Cytokeratin 19 fragment CYFRA 21-1 compared with carcinoembryonic antigen, squamous cell carcinoma antigen and neuron-specific enolase in lung cancer. Results of an international multicentre study.

The diagnostic value of the water-soluble cytokeratin 19 fragment CYFRA 21-1 in lung cancer was assessed in comparison with carcinoembryonic antigen, squamous cell carcinoma antigen, and neuron-specific enolase. The cut-off value, defined as 95% specificity versus a group of 526 patients suffering from benign chest diseases, was set at 3.3 micrograms/l for cytokeratin 19 fragment CYFRA 21-1 (carcinoembryonic antigen: 7.8 micrograms/l, squamous cell carcinoma antigen: 1.9 micrograms/l, neuron-specific enolase: 13.7 micrograms/l). Elevated pretreatment cytokeratin 19 fragment CYFRA 21-1 concentrations were recorded: in 112 of 244 (46%) patients with all histological types of lung cancer (carcinoembryonic antigen: 32%, squamous cell carcinoma antigen: 25%, neuron-specific enolase: 28%), in 89 of 177 (50%) patients with non-small cell lung cancer (carcinoembryonic antigen: 33%, squamous cell carcinoma antigen: 24%, neuron-specific enolase: 12%), in 47 of 81 (58%) patients with squamous cell carcinoma (carcinoembryonic antigen: 23%, squamous cell carcinoma antigen: 32%, neuron-specific enolase: 14%), in 27 of 63 (42%) patients with adenocarcinoma (carcinoembryonic antigen: 44%, squamous cell carcinoma antigen: 14%, neuron-specific enolase: 9%), in 15 of 33 (45%) patients with other non-small cell lung cancer (carcinoembryonic antigen: 36%, squamous cell carcinoma antigen: 24%, neuron-specific enolase: 14%), and in 20 of 55 (36%) patients with small cell lung cancer (carcinoembryonic antigen: 32%, neuron-specific enolase: 77%). Three of 12 patients with undefined histological type showed cytokeratin 19 fragment CYFRA 21-1 elevations. The best performance in terms of sensitivity and diagnostic accuracy was attained with the cytokeratin 19 fragment CYFRA 21-1 test in squamous cell carcinoma. In small cell lung cancer neuron-specific enolase was confirmed to be superior to the other markers. Cytokeratin 19 fragment CYFRA 21-1 concentrations increased with the extent of the malignant disease in non-small cell lung cancer. The positivity rate of cytokeratin 19 fragment CYFRA 21-1 in tumour stage TNM I was only 23% (carcinoembryonic antigen: 23%, squamous cell carcinoma antigen: 14%), i.e. the markers under study cannot be used for the diagnosis of early stage disease. Cytokeratin 19 fragment CYFRA 21-1 differentiated significantly between squamous cell carcinoma and the other histological types (p < 0.01). In addition, cytokeratin 19 fragment CYFRA 21-1 distinguished significantly the operable group TNM I-IIIa from inoperable TNM IIIb-IV (p < 0.05), but not TNM IIIa from IIIb. Out of 177 patients with non-small cell lung cancer, 90 individuals were monitored after surgery.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗

[Diagnosis, therapy and prognosis of atypical mycobacterial infections--results of a retrospective study].

The most important mycobacteria causing disease in humans are Mycobacterium tuberculosis and Mycobacterium leprae. These germs contrast the so-called atypical mycobacteria. The importance of the atypical mycobacteria was recognized in the fifties. Even if the quantity of atypical mycobacterial disease has increased during the last decades in Germany, it is still a rare disease today, but it is seen in patients with acquired immunodeficiency syndrome more often nowadays. In the period from 1st January 1986 til 31st December 1992 31 HIV-negative patients with a diagnosis of atypical mycobacterial disease have been seen in the department for lung diseases in the Thoraxklinik Heidelberg-Rohrbach. During the same period an atypical mycobacterial disease was diagnosed in 12 out of 413 HIV-positive patients (2.9%) of the AIDS-ambulance of the skin hospital of the University of Heidelberg. Most of the HIV-negative patients showed additional diseases which reduce the immunological resistance. In HIV-positive patients an atypical mycobacteriosis heralds a severe immunodeficiency. Because it is a rare disease and an exact diagnosis is difficult to establish there is a lack of controlled clinical trials and therefore detailed therapeutical guidelines do not exist. A therapeutical approach is also complicated by a lack of effective drugs. With disseminated disease in AIDS-patients, which is mostly caused by Mycobacterium avium-intracellulare, the therapy should be stopped, if there are any severe side-effects. The present results of therapy are still disappointing. In the future the management of atypical mycobacterial disease will be more important, because there is an increasing number of patients with acquired immunodeficiency.

AIDS-Related Opportunistic Infections↗

Levels of parathyroid hormone-related protein in hypercalcemia of malignancy: comparison of midregional radioimmunoassay and two-site immunoradiometric assay.

Overproduction of parathyroid hormone-related protein (PTHrP) is a major cause of hypercalcemia of malignancy in patients with solid tumors. We measured plasma levels of the protein by a radioimmunoassay (RIA) against PTHrP(53-84) and by an immunoradiometric assay (IRMA) against PTHrP (1-86). Of 16 affected patients 7 had elevated PTHrP levels in both assays and 4 had elevated levels in the RIA only. Median levels were about tenfold higher in these patients when measured by RIA (median of 34 versus 2.2 pmol/l). Measurements from both assays were, however, highly correlated with each other in this patient group (P < 0.01). PTHrP was not elevated in 10 normocalcemic patients with lung carcinoma. During long-term follow-up of a patient with a mesothelioma of the pleura, PTHrP levels measured with both assays decreased during chemotherapy in parallel with a normalization of serum calcium. In another hypercalcemic patient suffering from renal carcinoma, PTHrP measured by IRMA decreased by 40% within 12 h after nephrectomy, whereas PTHrP measured by RIA did not show a significant decline. Direct comparison of the assay results thus pointed to the existence of heterogeneity of circulating forms of PTHrP in plasma. In conclusion, both immunoassays detected elevated levels of PTHrP in a fraction of patients with hypercalcemia of malignancy and thus may be a tumor marker during treatment of malignancies.

Adult↗

Pharmaceutical properties, biodistribution, and imaging characteristics of manganese-mesoporphyrin. A potential hepatobiliary contrast agent for magnetic resonance imaging.

OBJECTIVES: Manganese (III) mesoporphyrin (Mn-mesoporphyrin) was investigated for its pharmaceutical properties and magnetic resonance imaging characteristics as a potential hepatobiliary contrast agent. METHODS: Solubility, partition coefficient, plasma binding, proton relaxation enhancement, biodistribution, biliary excretion, liver extraction ratio, and liver enhancement were measured in various in-vitro and in-vivo systems. RESULTS: Mn-mesoporphyrin was soluble and stable at moderate alkaline pH in phosphate buffer. The octanol/water coefficient was 25.98, and the compound was highly protein bound. R1 for water and plasma were 1.94 and 2.35 L/mmol sec, respectively. R1 in liver was calculated to be 15.72 L/mmol sec. Biodistribution studies in rats and mice confirmed hepatotrophic properties and biliary excretion was 65% over 24 hours. First pass liver uptake was 15%. Magnetic resonance imaging studies showed persistent liver enhancement at 0.05 mmol/kg. CONCLUSION: Mn-mesoporphyrin is a lipophilic compound that shows potential as a hepatobiliary magnetic resonance contrast agent.

Animals↗

The demonstration of human tumors on nude mice using gadolinium-labelled monoclonal antibodies for magnetic resonance imaging.

RATIONAL AND OBJECTIVES: The authors describe the magnetic resonance imaging (MRI) of a tumor in a nude mouse tumor model by means of an antibody-polylysine (Gd-DTPA) conjugate. METHODS: The monoclonal antibody, (MAB) RA96, was coupled to a polymeric gadolinium complex after periodate oxidation. This polymer, which consists of a polylysine backbone and complexing DTPA subunits, complexes an average of 65 gadolinium ions. RESULTS: The immunoreactivity of the conjugates was reduced by an average of only 30% compared with the unbound MAB RA96. Biodistribution studies in nude mice with subcutaneously implanted human colon carcinomas (WiDr [specific] and HT29 [control]) revealed a tissue concentration in the specific tumor of 8.72% of the dose applied per gram despite the high molecular weight of the conjugates. CONCLUSIONS: This tissue concentration is sufficient to achieve tumor-specific signal enhancement in the WiDr tumor on MRI. The problem of the high doses of protein required for MRI and possible solutions are discussed.

Animals↗

Cathepsin B and cysteine proteinase inhibitors in bronchoalveolar lavage fluid of lung cancer patients.

The enzymatic activity and the concentration of cathepsin B (CB), determined by ELISA, and total inhibitory activity of cysteine proteinase inhibitors (CPIs) were measured in bronchoalveolar lavage fluid (BALF) of lung tumor patients (n = 49). Significantly higher CB activity and concentration was found in BALF from metastasis (n = 15), when compared to squamous cell carcinoma (SCC; n = 15) and small cell lung carcinoma (SCLC; n = 7). Patients with adenocarcinoma (n = 12) also secreted considerably more CB, about 14- and 3.3-fold, compared to SCC and SCLC patients, respectively. However, only tumor patients without inflammation were considered because the comparison of patients with lung tumors (n = 49) and with other non-neoplastic lung diseases (n = 18) showed no differences due to high CB in BALF of patients with inflammatory conditions, present in some patients from both groups. Immunolabeling of tumor BALF proteins revealed CB immunoreactivity at molecular sizes that corresponded to the size of its precursor and mature forms, as well as to complexes with kininogen(s) and low molecular weight CPIs. Stefins A and B, but not cystatins C and S appeared in the complexes with CB.

Adenocarcinoma↗

Establishment of an enzyme-linked immuno-sorbent assay for urinary trypsin inhibitor by using a monoclonal antibody.

Monoclonal antibodies against inter-alpha-trypsin-inhibitor (ITI) were produced. One clone showing specificity for urinary trypsin inhibitor (UTI), a proteolytic fragment of ITI, which is excreted into urine, was selected for the establishment of an enzyme-linked immuno-sorbent assay (ELISA). The ELISA for the quantification of UTI was shown to work reproducibly in the range between 0.5 and 10 ng UTI/ml urine. Urines of several patients suffering from different lung diseases were screened for UTI using the established ELISA. Highest UTI levels were found in the urine of patients with lung empyema. A more moderate increase was observed in patients suffering from lung tuberculosis and from secondary and primary lung tumors.

Alpha-Globulins↗