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Biomedical subjects

A Schuster

Publications and source records attributed to A Schuster.

At least 73 records · Page 4Linked to original sources
PubMed1995

Cytokines in neutrophil-dominated airway inflammation in patients with cystic fibrosis.

Bronchopulmonary disease in patients with cystic fibrosis (CF) is a paradigm of neutrophil-dominated airway inflammation. We hypothesized that proinflammatory cytokines contribute to a localized neutrophil-dominated inflammatory state as present in CF airways. In a cross-sectional study, we analyzed 63 sputum samples from 33 CF patients for concentrations of the cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-8, tumor necrosis factor-alpha (TNF-alpha), and granulocyte-colony stimulating factor (G-CSF) by means of enzyme-linked immunosorbent assay. Furthermore, the activity of neutrophil elastase (NE) in the sputum samples was determined using a specific chromogenic substrate. Compared to sputum samples from 10 healthy controls, there were significantly increased concentrations of IL-1 beta, IL-8 and TNF-alpha in the CF sputum samples. The concentration of IL-8 correlated significantly with NE activity in the CF sputum samples. In CF patients with airways chronically colonized with Pseudomonas aeruginosa, IL-8 concentrations in sputum were significantly enhanced. In glucocorticoid-treated patients, IL-1 alpha and G-CSF sputum concentrations were significantly lower when compared to levels in the other patients. These results show that there are high concentrations of proinflammatory cytokines in CF airways which may contribute to the localized neutrophil-dominated inflammatory state found clinically.

Adolescent↗
PubMed1995

Heavy metal mediated inhibition of rBAT-induced amino acid transport.

rBAT, a protein which is located in the brush border membranes of intestine and renal proximal tubule cells, was recently shown to induce electrogenic countertransport of neutral and dibasic amino acids after its expression in Xenopus oocytes. Here, we studied the effects of heavy metals on rBAT induced amino acid transport in Xenopus oocytes to clarify a possible involvement of rBAT in heavy metal-induced aminoaciduria. The heavy metals Hg2+ and Pb2+ inhibited rBAT-induced amino acid transport with a different profile of action. The Pb2+ mediated inhibition occurred rapidly upon superfusion and was readily reversible upon washout. The maximal inhibition caused by Pb2+ was about 50% of the amino acid-induced currents at an apparent affinity (Km) of about 10 microM. In contrast, the Hg(2+)-mediated inhibition occurred rather slowly, depending on its concentration, and was not reversible during washout with control solution. However, the Hg(2+)-mediated amino acid transport inhibition could be reversed with Hg2+ chelating agents and reducing compounds. Other oxidative agents, such as the membrane permeable 2,2'-Dithio-bis(5-Nitropyridine) (DTNP), but not the membrane impermeable 5,5'-Dithio-bis (2-Nitrobenzoic acid) (DTNB), mimicked the effect of Hg2+, and their effect could similarly be reversed with 2,3-Dihydroxybutane-1,4-dithiol (DTE). In conclusion, Pb2+ and Hg2+ inhibit rBAT-induced amino acid transport in a noncompetitive, allosteric fashion. Blockade of rBAT-induced amino acid transport may be involved in aminoaciduria following mercury or lead intoxication.

Amino Acid Transport Systems, Basic↗
PubMed1995

Alpha 1-proteinase inhibitor abrogates proteolytic and secretagogue activity of cystic fibrosis sputum.

Airway disease in cystic fibrosis (CF) is characterized by neutrophil-dominated chronic inflammation with an excess of uninhibited neutrophil elastase (NE), which is regarded as an important factor in progressive lung destruction. Therefore, inhalation of alpha 1-proteinase inhibitor (alpha 1-PI) seems to be a reasonable therapeutic approach. To estimate its therapeutic potential, we quantitatively investigated the in vitro interactions of exogenous alpha 1-PI with CF sputum samples (n = 28). High NE and alpha 1-PI concentrations were detected in CF sputum (6.03 +/- 0.78 and 2.56 +/- 0.16 mumol/l, respectively). There was significant NE activity (2.6 +/- 0.4 U/l) due to both the surplus of NE and proteolytic degradation of alpha 1-PI. Addition of exogenous alpha 1-PI resulted in a dose-dependent inhibition of NE activity in CF sputum; > 90% inhibition was achieved at 10 micrograms/ml alpha 1-PI. Purified NE as well as CF sputum potently induced secretion from porcine tracheal glands. Corresponding to inhibition of NE activity, CF sputum-induced secretion was also inhibited by exogenous alpha 1-PI; > 90% inhibition was also achieved at 10 micrograms/ml alpha 1-PI. Incubation of exogenous alpha 1-PI with CF sputum for 24 h did not reduce the inhibitory effects. From our in vitro results we conclude that inhalation of alpha 1-PI might effectively inhibit both NE activity and airway gland hypersecretion in CF airways.

Adolescent↗
PubMed1995

Cystic fibrosis sputum induces a secretory response from airway gland serous cells that can be prevented by neutrophil protease inhibitors.

High activities of the neutrophil proteases, elastase and cathepsin G, are found in the sputum of patients with cystic fibrosis (CF). Because both proteases have been shown to be potent secretagogues for airway submucosal glands, and because hypersecretion is a characteristic feature of CF, the objective of the present study was to examine whether there is secretagogue activity in CF sputum, and to determine the contribution of neutrophil proteases to the secretagogue activity. Confluent monolayers of cultured bovine tracheal serous cells were pulse-labelled with Na2(35)SO4, incubated with diluted CF sputum supernatants in the presence or absence of different protease inhibitors, and the subsequent release of the radio-labelled macromolecules was measured. CF sputum potently induced secretion concentration-dependently. Addition of the selective neutrophil elastase inhibitor ICI 200,355 inhibited the secretory response to CF sputum supernatant by 89%. Addition of a cathepsin G-inhibitor resulted in further inhibition of the secretory response. Addition of phosphoramidon, a drug known to inhibit Pseudomonas aeruginosa elastase, had no effect. We conclude that CF sputum potently stimulates airway submucosal gland cell secretion. These studies with protease inhibitors suggest that neutrophil proteases account substantially for the secretagogue activity present in CF sputum.

Adult↗
PubMed1995

Properties of electrogenic Pi transport by a human renal brush border Na+/Pi transporter.

Inorganic phosphate (Pi) induced an inward current (IP) in Xenopus oocytes expressing the human renal Na+/Pi cotransporter NaPi-3. At 100mM Na+, Pi-transport was independent of the holding potential and resulted in an apparent Km of 0.08 mM; lowering the Na+ concentration to 50 mM resulted in an increase of the apparent Km to 0.22 mM at -50 mV and to 0.31 mM at -90 mV. In contrast, the apparent Km for Na+ was not significantly influenced by the holding potential. A decrease of the pH from 7.8 to 6.8 resulted in a decrease of IP at 50 mM Na+, but not at 150 mM Na+. Arsenate induced inward currents through NaPi-3 and decreased the apparent Km in measurements of IP. Phosphonoformic acid itself induced no currents, but inhibited Pi-induced currents with an apparent Ki of 3.6 mM. In summary, NaPi-3 displays characteristic Na+/Pi cotransporter properties with relevant interactions with arsenate (transport substrate) and phosphonoformic acid (inhibitor). Monovalent and divalent Pi both appear to be transported by NaPi-3.

Animals↗
PubMed1995

Presurgical visualization of primary breast carcinoma with PET emission and transmission imaging.

UNLABELLED: The aim of this study was to investigate a technique that visualizes findings from PET images in a context useful for surgery. METHODS: Simultaneously acquired PET emission and transmission scans were used. By applying a multipurpose imaging, registration and rendering tool (MPM), displays of orthogonal and volume-rendered views or any combination thereof were obtained. The PET emission and transmission scans were acquired under routine conditions. The final user-customized display (with a combination of orthogonal cuts and rendered views) was processed in 10 min or less on commercially available hardware. Distinct features of the body shape were clearly visible on the volume-rendered transmission views. Hot spots, e.g., in primary breast cancer, from the emission scans could be easily assessed in their localization relative to the body outline. CONCLUSION: Rendering of the main signatures in a single comprehensive display makes this method potentially valuable for simple presurgical workup and therapeutic management of breast cancer.

Breast Neoplasms↗
PubMed1995

Clinical experience transferring kidney transplant patients from Sandimmun to Sandimmun Neoral--results after 3 months.

The new galenic formulation of cyclosporine prepared as microemulsion (Sandimmun Neoral, SN) shows a significantly improved correlation between both trough level (Cmin) and dose. Moreover, since the bioavailability is increased by 20 to 30% on average, it may lead to a drug overexposure in so far malabsorbing patients. In order to assess safety and to establish an appropriate procedure to switch patients safely from conventional Sandimmun to SN, we initialized an open, stratified (transplant age) clinical trial enrolling 302 patients of our outpatient clinic. We used a simple 1:1 conversion of the patient's total daily dose. Trough drug levels, as well as serum creatinine, liver enzymes, uric acid, and blood pressure values were measured at baseline, at days 4, 8, 15, 29, and at month 3 after drug substitution. Within the three month observation period, the cyclosporine dose was reduced by 14.2% (204 +/- 60 mg/day baseline vs. 175 +/- 54 mg/day after conversion, p < 0.05). By day 8, the 1:1 dosage conversion resulted in a modest mean increase in drug trough levels (114 ng/ml baseline vs. 120 ng/ml, p < 0.05). This increase was accompanied by a slight increase in mean serum creatinine concentration, a decrease in calculated creatinine clearance, and an increase in mean uric acid values (p < 0.05). Liver enzymes remained unchanged while systolic and mean arterial blood pressure decreased (p < 0.05). Parallel to dosage reduction, drug trough levels had decreased after 1 month to baseline (112 ng/ml) and remained there for the remainder of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Availability↗
PubMed1994

A 17-kDa Nicotiana tabacum cell-wall peptide acts as an in-vitro inhibitor of the cell-wall isoform of acid invertase.

When cell-wall invertase (CWI) from Nicotiana tabacum L. cell-suspension cultures, either non-transformed or transformed with Agrobacterium tumefaciens, was salt-eluted from intact cells and purified on Sulfopropyl-Sephadex (SPS) by pH-gradient elution, the enzyme lost about 50% of its activity during a 1-h incubation at pH 4.8. However, Western-blot analysis indicated no appreciable enzyme degradation. Re-chromatography of CWI peak fractions on SPS using NaCl-gradient elution showed the presence of a 17-kDa peptide (p17) in fractions with low CWI activity but strong CWI immunosignal (Weil and Rausch 1994, Planta 193, 430-437). When separating CWI from p17 by Concanavalin A (Con A)-Sepharose chromatography, inhibition could be restored by incubating the inhibitor-containing fraction with inhibitor-free CWI. More than 90% of CWI could be inhibited, suggesting that all CWI was susceptible to p17 binding. The presence of divalent metal ions (Ca2+, Mg2+, Zn2+) during pre-incubation of CWI with p17 reduced CWI inhibition substantially. Also, sucrose protected CWI against inhibition by p17 (half-maximum protection at 1.3 mM). Binding of p17 to CWI during a 1-h pre-incubation was pH-dependent, pH 4.5 causing maximum inhibition, whereas at pH 6.5 no inhibition was observed. Gel-permeation chromatography revealed that the native inhibitor acts as a monomer. Immunoprecipitation of CWI co-precipitated p17, confirming direct binding of p17 to CWI. When fractions containing CWI and p17 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent Western blotting a diffuse immunosignal of 86-90 kDa was observed (in addition to the prominent CWI signal at 69 kDa).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Cell type-specific MxA-mediated inhibition of measles virus transcription in human brain cells.

Measles virus (MV)-specific transcription in human brain cells is characterized by particularly low abundances of the distal mRNAs encoding the MV envelope proteins. Similar transcriptional restrictions of the closely related vesicular stomatitis virus have been observed in mouse fibroblasts constitutively expressing the interferon-inducible MxA protein (P. Staeheli and J. Pavlovic, J. Virol. 65:4498-4501, 1991). We found that MV infection of human brain cells is accompanied by rapid induction and high-level expression of endogenous MxA proteins. After stable transfection of MxA, human glioblastoma cells (U-87-MxA) released 50- to 100-fold less infectious virus and expression of viral proteins was highly restricted. The overall MV-specific transcription levels were reduced by up to 90%, accompanied by low relative frequencies of the distal MV-specific mRNAs. These restrictions were linked to an inhibition of viral RNA synthesis and not to a decreased stability of the viral RNAs. Our results indicate that expression of MxA is associated with transcriptional attenuation of MV in brain cells, thus probably contributing to the establishment of persistent MV central nervous system infections. In addition, the mechanism of MxA-dependent resistance against MV infection, in contrast to that of vesicular stomatitis virus, is cell type specific, because an inhibition of MV glycoprotein synthesis independent of transcriptional alterations was observed in MxA-transfected human monocytes (J. J. Schnorr, S. Schneider-Schaulies, A. Simon-Jödicke, J. Pavlovic, M. A. Horisberger, and V. ter Meulen, J. Virol. 67: 4760-4768, 1993).

Animals↗
PubMed1993

Does pertussis infection induce manifestation of allergy?

To evaluate whether pertussis induces the development of allergy, a prospective study was performed in 25 children aged 0.8-12.2 years. The patients underwent allergy diagnostics during pertussis infection and at a follow-up visit 8-14 months later. Diagnostic criteria included the medical history of the patients and their families, a modified skin prick test, measurement of serum IgE and radio-allergosorbent test screening for specific sensitizations. At the time of pertussis, serum IgE concentration in the study group was 62 +/- 30 kU/ml. At the follow-up visit, there was a significant increase in serum IgE to 137 +/- 51 kU/ml, which was also significantly higher than IgE in an age-matched control group. Children at a significantly higher risk for developing IgE increase or new allergic sensitizations were those with a family history of allergy or potentially allergic disease in their personal history. Our results indicate that pertussis may induce IgE production in affected children.

Child↗
PubMed1993

[Intravenous immunoglobulins in bronchial asthma: a therapeutic alternative?].

Treatment of severe bronchial asthma usually requires the use of steroids. Given the known side effects of steroid treatment, potential alternative therapeutical strategies are currently evaluated; among others, intravenously administered immunoglobulins (ivIg) may be considered. In one study of 5 children with bronchial asthma and IgG subclass deficiency, an improvement of asthma was demonstrated in 4 out of the 5 patients under ivIg treatment over several months. In another study on ivIg treatment in 8 immunocompetent children with steroid-dependent asthma, there also was an improvement of asthma, leading to a reduction in the required steroid dose; furthermore, there was a diminution in skin prick test reactivity. At present, only speculations can be made about the possible mechanisms of action.

Adolescent↗
PubMed1992

Neutrophil elastase stimulates tracheal submucosal gland secretion that is inhibited by ICI 200,355.

To investigate whether human neutrophil elastase (HNE) stimulates airway submucosal gland secretion, we studied the effect of purified HNE on secretion of 35S-labeled macromolecules from isolated tracheal tissues from ferrets, dogs, and humans. HNE stimulated secretion in a concentration-dependent fashion, the secretory response being most pronounced in ferret tissues with a maximal response of 1,498 +/- 384% above baseline at 10(-5) M. In dog tissues, maximal secretory responses (509 +/- 169%) to HNE were much greater than to bethanechol (80 +/- 26%). Human tissues obtained several hours postmortem still responded to HNE (179 +/- 48% at 10(-5) M) significantly more than to the combination of isoproterenol, phenylephrine, and bethanechol (23 +/- 10%). Morphometric analysis of canine tracheal tissues showed degranulation of submucosal gland cells after HNE. A specific inhibitor of HNE (ICI 200,355) potently inhibited secretory responses in a concentration-dependent fashion. We suggest that HNE in airways of patients may cause hypersecretion and that treatment with ICI 200,355 may provide a strategy for therapeutic intervention.

Animals↗
PubMed1992

Role of neutrophil elastase in allergen-induced lysozyme secretion in the dog trachea.

To test our hypothesis that neutrophil elastase plays a role in airway hypersecretion associated with the allergic late-phase response, using an isolated tracheal segment system in vivo and measuring lysozyme activity in the perfusate of the lumen as a marker of submucosal gland secretion over 8 h, we studied the response of five allergic dogs to ragweed. The dogs were exposed on separate occasions to specific allergen, to allergen vehicle, and to allergen in the presence of a selective neutrophil elastase inhibitor, ICI 200,355. Allergen exposure caused a marked increase in lysozyme secretion that was significantly increased at 4, 6, and 8 h compared with controls and ICI 200,355-treated dogs. Neutrophil elastase appeared in the perfusate after allergen exposure and was positively correlated with lysozyme secretion at 8 h. These findings suggest that neutrophil elastase plays an important role as a secretagogue in the allergic late-phase response.

Allergens↗
PubMed1992

Mucus hypersecretion in bronchiectasis. The role of neutrophil proteases.

To investigate the role of neutrophil proteases in the pathogenesis of mucus hypersecretion in bronchiectasis, we collected sputum samples from seven patients with bronchiectasis and measured their secretagogue activity by examining secretion of radiolabeled macromolecules by bovine airway submucosal gland cells incubated with sputum supernatants. There was marked secretagogue activity in bronchiectasis sputum, reaching a maximum of 1,963 +/- 292% (mean +/- SEM) above baseline at 1:15 dilution. Addition of ICI 200,355 (10(-5) M), a selective human neutrophil elastase inhibitor, decreased the secretory response markedly (72.53 +/- 5.89% reduction). The combination of aprotinin, an inhibitor of cathepsin G, and ICI 200,355 caused significantly more reduction in the secretory response than ICI 200,355 alone (89.12 +/- 3.8 versus 72.53 +/- 5.89% reduction, p < 0.05). We conclude that bronchiectasis sputum causes a large secretory response from tracheal submucosal glands due mostly to neutrophil proteases.

Adult↗
PubMed1991

Cytostatic synergism between bromodeoxyuridine, bleomycin, cisplatin and chlorambucil demonstrated by a sensitive cell kinetic assay.

Bromodeoxyuridine/Hoechst flow cytometry was used to analyse the interference of common cytostatic agents with cell activation and cell cycle progression of human B-cell lines. Bleomycin impaired both cell activation and G2 transit, the latter effect being oxygen dependent. The DNA alkylating agents cyclophosphamide, chlorambucil and mitomycin C caused G2 arrest, whereas cisplatin arrested cells in both the S and G2 phase of the cell cycle. Vinblastin interfered with mitosis, but in addition arrested cells in all phases of the cell cycle. The growth inhibitory action of bleomycin, cisplatin and chlorambucil was dependent upon the bromodeoxyuridine (BrdU) concentration in the culture medium. No interaction was found between BrdU and cyclophosphamide, mitomycin C and vinblastin. The cell cycle kinetic mechanism of the interaction between BrdU and bleomycin, cisplatin and chlorambucil was a potentiation of the G2 arrest. In conclusion, BrdU may be useful in clinical chemotherapy as a chemosensitizer for selected cytostatic agents.

Bleomycin↗
PubMed1991

Control of proven pulmonary and suspected CNS aspergillus infection with itraconazole in a patient with chronic granulomatous disease.

An 11-year-old boy with chronic granulomatous disease caused by cytochrome b deficiency developed right upper lung lobe aspergillosis. Intracerebral lesions developed on maximum doses of flucytosine and amphotericin B. Treatment with 16 mg/kg oral itraconazole was followed by a dramatic clinical improvement and almost complete disappearance of the intracerebral lesions. Plasma itraconazole levels were between 40 and 3440 ng/ml depending on concomitant medication. Toxicity was restricted to transient elevation of alkaline phosphatase and gamma glutamyl transferase. We conclude that further trials with itraconazole are justified in high risk patients in whom conventional therapy has failed.

Antifungal Agents↗