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C Weber

Publications and source records attributed to C Weber.

At least 91 records · Page 5Linked to original sources
PubMed2000

A non-peptide functional antagonist of the CCR1 chemokine receptor is effective in rat heart transplant rejection.

Chemokines like RANTES appear to play a role in organ transplant rejection. Because RANTES is a potent agonist for the chemokine receptor CCR1, we examined whether the CCR1 receptor antagonist BX471 is efficacious in a rat heterotopic heart transplant rejection model. Treatment of animals with BX471 and a subtherapeutic dose of cyclosporin (2.5 mg/kg), which is by itself ineffective in prolonging transplant rejection, is much more efficacious in prolonging transplantation rejection than animals treated with either cyclosporin or BX471 alone. We have examined the mechanism of action of the CCR1 antagonist in in vitro flow assays over microvascular endothelium and have discovered that the antagonist blocks the firm adhesion of monocytes triggered by RANTES on inflamed endothelium. Together, these data demonstrate a significant role for CCR1 in allograft rejection.

Animals↗
PubMed2000

New attempt to determine the n-n scattering length with the 2H(n, np)n reaction

The n-n final-state interaction (FSI) was investigated via the 2H(n, np)n reaction at 25 MeV, using a geometry which enables the simultaneous observation of n-p quasifree (QFS) scattering. The data were analyzed with Monte Carlo simulations based on rigorous Faddeev calculations with realistic nucleon-nucleon potentials. The value of a(nn) deduced from the absolute yield in the FSI peak is -16.27+/-0. 40 fm while the relative data, normalized in the QFS region, give -16.06+/-0.35 fm. Thus our results differ from the "recommended" value of a(nn) = -18.5+/-0.3 fm by more than 5 standard deviations.

Journal Article↗
PubMed2000

Hemodynamic effects of Bosentan, an endothelin receptor antagonist, in patients with pulmonary hypertension.

BACKGROUND: Few treatments are available for isolated pulmonary hypertension (PHT), which has a high morbidity and mortality. This trial was designed to assess the hemodynamic effects of bosentan, an endothelin receptor antagonist, in patients with PHT, in which local overproduction of endothelin-1 (ET-1) is thought to play a pathogenic role. METHODS AND RESULTS: An open-label, dose-ranging study was performed in 7 female patients with primary PHT (n=5) or isolated PHT associated with limited scleroderma (n=2). Infusions of 50, 150, and 300 mg were administered at 2-hour intervals, and the hemodynamic responses were measured. Bosentan caused a dose-dependent fall in total pulmonary resistance (-20.0+/-11.0%, P=0.01) and mean pulmonary artery pressure (-10.6+/-11.0%, P>0.05). However, there was also a fall in the systemic vascular resistance (-26.2+/-12.8%, P<0.005) and mean arterial pressure (-19.8+/-14.4%, P<0.001). There was a slight increase in cardiac index (15+/-12%, P>0.05) and a dose-dependent rise in ET-1 but no significant change in other hemodynamic variables, gas exchange, or other vasoactive mediators. CONCLUSIONS: Intravenous bosentan is a potent but nonselective pulmonary vasodilator at the doses tested, even in patients resistant to inhaled nitric oxide. Transient increases in plasma ET-1 were observed, consistent with a blockade of endothelial ET(B) receptors. Systemic hypotension and other significant events during the study indicate that its intravenous use in patients with severe PHT may be limited. Implications for future trial design and studies of chronic oral treatment are discussed.

Adult↗
PubMed2000

Desolvation process and surface characteristics of HSA-nanoparticles.

The objective of the present study was to characterise and optimise the desolvation process of human serum albumin (HSA) for the preparation of nanoparticles. Following the desolvation of the protein, the resulting nanoparticles were stabilised by the addition of varying amounts of glutaraldehyde. The particle size and the number of available amino groups on the surface of the nanoparticles were determined. The results indicated that the particle size depended mainly on the amount of desolvating agent added, but not on the amount of cross-linker. Increasing volumes of glutaraldehyde reduced the number of amino groups on the surface of HSA nanoparticles.

Chemistry, Pharmaceutical↗
PubMed2000

The effect of acute immobilization stress on the abundance of corticotropin-releasing factor receptor in lymphoid organs.

We have previously found a dramatic increase of corticotropin-releasing factor receptor (CRF-R1) production in splenic neutrophils of male C57BL/6N mice after application of an immunological stimulus. We demonstrate here that immobilization, a predominantly psychological stress, exhibited a similar effect. Shortly after 90 min of immobilization, the number of splenic CRF-RI+ cells was transiently increased by nearly 8-fold, while it was reduced in thymus and unchanged in lymph nodes. The CRF-R1+ cells were detected by an affinity-purified polyclonal antibody directed against the N-terminus of CRF-R1, and identified as neutrophils, eosinophils or their immature precursors on the basis of their nuclear shapes, Wright-Giemsa staining and colocalization of CRF-R1 with the ER-MP58 antigen.

Animals↗
PubMed2000

Desolvation process and surface characterisation of protein nanoparticles.

The objective of the present study was to characterise and optimise the desolvation process of human serum albumin (HSA) for the preparation of nanoparticles and to characterise the resulting colloidal system. Following the desolvation of the protein, the resulting nanoparticles were stabilised by the addition of varying amounts of glutaraldehyde or by heat denaturation. The particle size, zeta potential, and the number of available amino groups on the surface of the nanoparticles were determined. The amino groups were quantified by a spectrophotometric method using 2,4, 6-trinitrobenzenesulfonic acid (TNBS). The results indicated that the particle size depended mainly on the amount of desolvating agent added, but not on the amount of cross-linker or the kind of cross-linking procedure. Increasing amounts of glutaraldehyde reduced the number of amino groups on the surface of HSA nanoparticles and also decreased the zeta potential of the carrier system. The temperature and heat denaturation time only had an influence on the stability of the nanoparticles but not on the amount of amino groups or the particle size. It was shown that heat denatured HSA nanoparticles possessed the greatest number of amino groups on their surface. Additional experiments for the characterisation of gelatin A and B nanoparticles were performed.

Colloids↗
PubMed2000

Differential chemokine receptor expression and function in human monocyte subpopulations.

The subset of human blood monocytes expressing low levels of CD14 and high levels of CD16 (CD14+CD16+) exhibits features resembling mature tissue macrophages and can be expanded in inflammatory conditions. We analyzed expression of CC chemokine receptors (CCR) in CD14+CD16+ versus CD14++ monocytes, which may be crucial for specific trafficking. Multicolor flow cytometric analysis of whole peripheral blood revealed that, as opposed to CD14++ monocytes, the CD14+CD16+ subset lacked surface expression of monocyte chemotactic protein-1 (MCP-1) receptor CCR2, however, it showed significantly higher surface expression of the macrophage inflammatory protein 1alpha (MIP-1alpha)/RANTES receptor CCR5. This was paralleled by differences in mRNA expression in the subsets, as shown by reverse transcriptase-polymerase chain reaction using sorted cells. In comparison to CD14++ monocytes, CD14+CD16+ cells expressed lower CCR2 but higher CCR5 transcript levels, whereas CCR1 levels were equivalent. Flow cytometric analysis of isolated human monocytes recovered after transendothelial chemotaxis assays revealed that the percentage of CD14+CD16+ cells was dramatically reduced in the fraction migrating toward MCP-1 compared with the fraction that did not migrate or the input, showing that polarized CCR2 expression was accompanied by a differential chemotactic responsiveness. Moreover, CD11b surface expression was preferentially up-regulated by MCP-1 in CD14++ cells but by MIP-1alpha in CD14+CD16+ monocytes, confirming the functional relevance of distinct CCR expression. The characteristics of CD14+CD16+ cells may reflect preactivation by cytokines and determine their predilective localization during specific inflammatory conditions or susceptibility to infection.

Antigens, CD↗
PubMed2000

Lipopolysaccharide-induced nasal cytokine response: a dose-response evaluation.

Information on the dose-response relationship is a prerequisite to defining the non-response threshold of exposure. We investigated whether nasal lipopolysaccharide (LPS) challenges induce an inflammatory response in a dose-dependent way. In three settings nasal lavage was performed before, and 20 min, 1, 6, 23, and 29 h after instillation of 0 microg, 10 microg, and 40 microg LPS for 10 s, in seven healthy subjects. Lavage fluids were analysed for concentrations of interleukin-6 (IL-6), IL-8, tumour necrosis factor-alpha (TNF-alpha), histamine, and albumin. Symptoms were recorded by questionnaire and spirometric lung function was assessed after each lavage. The instillation of 40 microg LPS caused a small increase in nasal symptoms. TNF-alpha was below the detection limit (0.5 pg/ml) in most subjects and, like IL-8 and albumin, showed no relation to the LPS challenge. IL-6 increased over twofold with 10 microg LPS and over 13-fold with 40 microg LPS, with a peak at 6 h after LPS provocation, and the repeated design ANOVA was significant for dose and for time. Six hours after the 40 microg LPS challenge the histamine level significantly increased compared to the saline treatment. We conclude that short-lasting instillation of LPS causes a dose-dependent IL-6 release in the upper airways and minor nasal symptoms.

Administration, Inhalation↗
PubMed2000

Modulation of vascular cell activation, function, and apoptosis: role of antioxidants and nuclear factor-kappa B.

The activity of NF-kappa B is critically involved in the inflammatory activation of endothelial cells and their adhesiveness and also appears to regulate apoptosis in SMC by coordinating antiapoptotic programs. The activity of NF-kappa B has been revealed within human atheromas or following angioplasty but not in undiseased arteries. Hence, the inhibition of NF-kappa B mobilization by antioxidative or anti-inflammatory agents or by adenoviral I kappa B alpha overexpression, as reviewed herein, may act in concert to suppress endothelial activation and to induce SMC apoptosis. This synergistic concept may be a vasoprotective approach to prevent atherogenesis and restenosis by attenuating inflammatory reactions and SMC proliferation in nascent and progressing atherosclerotic lesions, as well as in developing neointima formations following angioplasty.

Animals↗
PubMed2000

Improved detection and differentiation of poleroviruses infecting beet or rape by multiplex RT-PCR.

Three distinct species of virus inducing yellowing of beet, Beet mild yellowing virus (BMYV), Brassica yellows virus (BrYV, synonym BWYV) and Beet chlorosis virus (BChV) have been characterised from the genus Polerovirus. Until recently, no available tools were available to allow accurate and reliable distinction of the three species. Based on previous nucleotide sequence alignments and phylogenetic studies, we show that the use of molecular methods enabled the discrimination of these three beet Polerovirus species, but with differences in efficiency and specificity. Primers CP+ and CP- encompassing ORF-3, which encodes the coat protein, allowed the amplification by RT-PCR of a fragment of 563 bp for all isolates. Molecular methods such as SSCP or RFLP were able to discriminate these fragments by utilizing the differences in sequence. However, SSCP is a highly sensitive technique and was not suitable for the distinction of the Polerovirus species, because all isolates tested displayed a unique pattern. Analysis of the ORF3 RT-PCR products, digested with SmaI, RsaI and AccI restriction enzymes revealed four distinct patterns specific for the three species. However, point mutations can alter the RFLP patterns, making the interpretation of the results difficult. Primers were designed to amplify specifically sequences corresponding to ORF-0 of the three viral species. By using the three new sets of ORF-0 specific primers and CP+/CP- primers in a single multiplex RT-PCR, the detection and discrimination of the three beet Polerovirus species was possible in infected plants. The multiplex RT-PCR method provides a reliable and highly sensitive method to detect and identify viral species and will be of great interest for epidemiological studies of beet poleroviruses.

Brassica↗
PubMed2000

Preparation of avidin-labeled protein nanoparticles as carriers for biotinylated peptide nucleic acid.

The possibility of preparing protein nanoparticles followed by covalent linkage of avidin was investigated. Free sulfhydryl groups were introduced onto the surface of protein nanoparticles either by aldehyde quenching with cysteine or reaction of free amino groups with 2-iminothiolane. The number of primary amino groups and sulfhydryl groups on the surface of the resulting particles was quantified with site-specific reagents. Avidin was attached to the surface of the thiolated nanoparticles via a bifunctional spacer which reacted in a first step with amino groups of avidin and in a second step with the sulfhydryl groups introduced onto the surface of the nanoparticles. Biotinylated peptide nucleic acid (PNA) as a model compound for biotinylated drugs was effectively coupled to the nanoparticles by complex formation with the covalently attached avidin. Since the formation of the interaction between biotin and avidin is very rapid and stable a highly effective drug carrier system for biotinylated compounds such as PNAs was achieved.

Avidin↗
PubMed2000

Purging in BCR-ABL-positive acute lymphoblastic leukemia using immunomagnetic beads: comparison of residual leukemia and purging efficiency in bone marrow vs peripheral blood stem cells by semiquantitative polymerase chain reaction.

Twenty autologous bone marrow (BM) and 25 peripheral blood stem cell (PBSC) grafts were collected from a total of 40 consecutive patients with BCR-ABL+ acute lymphoblastic leukemia (ALL) in first (n = 37) or second (n = 3) complete morphological remission and subsequently purged with a cocktail of anti-CD19, -CD10, AB4 MoAbs and immunomagnetic beads (IMB). Residual BCR-ABL-positive cells before purging were detected in 19 of 20 BM grafts at a median of 4 (range 0-6) logs and in 17 of 25 evaluable PBSC grafts at a median of 1 (range 0-3) log above the limit of detection assessed by a semiquantitative limiting log10-dilution RT-PCR (P < 0.0001). IMB purging depleted a median of 2.5 (range 1-4) log of residual BCR-ABL+ cells from BM and a median of 1 (range 0-2) log from PBSC grafts, achieving RT-PCR negativity in 1/20 BM and 12/25 PBSC grafts after purging. Cell recoveries were 62% and 86% (P < 0.0001) of MNC and 74% and 97% (P = 0.065) of CD34+ cells after BM and PBSC purging, respectively. BM purging was superior using the triple MoAb cocktail which depleted 2.64 +/- 0.4 log (n = 14) compared to 1.6 +/- 0.4 log (n = 5) using the MoAb cocktail not including AB4 (P = 0. 02). We conclude that unpurged BM grafts contain 2-3 log more residual BCR-ABL+ cells than unpurged PBSC grafts and that purging efficacy is superior in BM compared to PBSC grafts, but median titers in purged BM grafts still exceed those in purged PBSC grafts. Bone Marrow Transplantation (2000) 25, 97-104.

Adolescent↗
PubMed2000

Quality assurance in RT-PCR-based BCR/ABL diagnostics--results of an interlaboratory test and a standardization approach.

Here we describe the results of an interlaboratory test for RT-PCR-based BCR/ABL analysis. The test was organized in two parts. The number of participating laboratories in the first and second part was 27 and 20, respectively. In the first part samples containing various concentrations of plasmids with the ela2, b2a2 or b3a2 BCR/ABL transcripts were analyzed by PCR. In the second part of the test, cell samples containing various concentrations of BCR/ABL-positive cells were analyzed by RT-PCR. Overall PCR sensitivity was sufficient in approximately 90% of the tests, but a significant number of false positive results were obtained. There were significant differences in sensitivity in the cell-based analysis between the various participants. The results are discussed, and proposals are made regarding the choice of primers, controls, conditions for RNA extraction and reverse transcription.

Base Sequence↗
PubMed2000

Renal hemodynamics and pharmacokinetics of bosentan with and without cyclosporine A.

UNLABELLED: Renal hemodynamics and pharmacokinetics of bosentan with and without cyclosporine A. BACKGROUND: Endothelins may play an important role in cyclosporine A (CsA)-induced renal vasoconstriction. Therefore, the effects of a mixed endothelin A and B receptor antagonist, bosentan (BO), on CsA were studied. METHODS: BO was given either alone or combined with CsA to healthy subjects in a double-blind, placebo-controlled, cross-over study. Standardized renal hemodynamics took place after a single dose of BO or placebo and after seven days of regular intake of CsA + BO or CsA + placebo. CsA was administered as a dose-adjusted regimen to achieve predetermined target trough levels. A pharmacokinetic study of CsA and BO was performed. RESULTS: A single dose of BO did not affect renal hemodynamics. After seven days of coadministration with CsA, BO significantly attenuated both the overall CsA-induced fall of renal plasma flow (RPF; placebo, 594 +/- 85; CsA + placebo, 490 +/- 93; CsA + BO, 570 +/- 106* mL/min, *P < 0.01) and the maximal RPF fall (P < 0.01) observed five hours after CsA intake. The CsA-induced rise of blood pressure and the decrease of glomerular filtration rate (GFR) were not influenced by comedication with BO. After seven days of CsA + BO, the area under the curve (AUC) of BO was nearly doubled compared with the AUC after a single dose of BO (P < 0.05). To reach the CsA target trough levels after seven days, the average CsA dose was increased by 35% when given with BO, as compared with placebo (P = 0.01). CsA exposure (trough levels, AUC) was not statistically different after CsA + placebo and after CsA + BO. CONCLUSIONS: Assuming CsA nephrotoxicity is mainly due to vasoconstriction, BO has the potential to attenuate the CsA renal toxicity by markedly blunting the renal hypoperfusion effect of CsA. A complex drug interaction between BO and CsA was observed.

Adult↗
PubMed2000

Novel online infusate-assisted dialysis system performs microbiologically safely.

Administration of adequate amounts of commercial infusion fluids renders modern convective dialysis modalities, such as hemodiafiltration, labor-intensive and costly. Preparation of infusate by cold sterilization of dialysis fluid, which is abundantly available, and its immediate (online) use, in contrast, enables a large volume fluid exchange in a cost-effective manner. Recent developments aimed at more hygienic and user-friendly online systems with increased operational flexibility. As a result the novel ONLINEplus system does not only provide online prepared infusate for convective dialysis therapy, but also for priming and rinsing of the extracorporeal blood circuit, for intradialytic bolus administration, and for re-infusion of patients' blood as well. Production of infusate from potentially impure dialysis fluid containing endotoxins and other pyrogens raises severe concerns of affecting the patients' well-being. To assess its safety, the online system was challenged with microbially contaminated dialysis fluid. Despite high levels of microbial counts (7.5 x 104 +/- 105 CFU/ml), endotoxin concentration (14.1 +/- 7.7 IU/ml and 9.265 +/- 3.000 IU/ml, as measured turbidimetrically and chromogenically, respectively) and cytokine-inducing activity (20,827 +/- 3,082 pg IL-1Ra/Mio WBC), we failed to detect contaminants in the final infusate during a 5 week laboratory testing period. In addition, infusate samples complied consistently with the European Pharmacopeia test for sterility. The present online system is comprehensive, operates user-friendly, and provides microbiologically safe infusate in large quantities. In this way, both patients and dialysis staff will benefit from improved dialysis therapy and reduced treatment-related labor burden, respectively. Moreover, convective dialysis modalities will become less expensive.

Analysis of Variance↗
PubMed2000

Cytokine induction in patients undergoing regular online hemodiafiltration treatment.

End-stage renal disease (ESRD) patients are known to suffer from chronic inflammation as the result of an ongoing subacute cytokine induction, which may contribute considerably to dialysis-related, long-term morbidity and mortality. Preparation of infusate from cytokine-inducing dialysis fluid and its administration in large quantities as well as the use of high-flux membranes bear the risk of aggravating the chronic inflammatory response among online hemodiafiltration (online HDF) patients. In order to assess the inflammatory risk associated with online HDF, we compared the cytokine induction profile of ESRD patients receiving either online HDF or low-flux hemodialysis (low-flux HD). Specifically, we measured spontaneous and lipopolysaccharide (LPS)-stimulated tumor necrosis factor alpha (TNFalpha) and interleukin-1 receptor antagonist (IL-1Ra) release during ex vivo incubation of whole blood. Ultrapure dialysis fluid and polysulfone membranes were used for both treatment modalities. LPS-stimulated release of TNFalpha and IL-1Ra was elevated for both online HDF and low-flux HD patients compared to healthy individuals (TNFalpha: 2,336 +/- 346 and 2,192 +/- 398 versus 1,218 +/- 224 pg/106 white blood cells [WBC]; IL-1Ra: 2,410 +/- 284 and 2,326 +/- 186 versus 1,678 +/- 219 pg/106 WBC). Likewise, spontaneous production of TNFalpha, but not IL-1Ra, was higher in online HDF and low-flux HD patients than in normal controls (37 +/- 32 and 22 +/- 19 versus 0.8 +/- 0.3 pg TNFalpha/106 WBC). There was no difference in spontaneous and LPS-stimulated cytokine release between both dialysis groups. In addition, intradialytic cytokine induction was not significant for either treatment modality as spontaneous and LPS-stimulated cytokine release were not increased postdialysis. These findings indicate that online HDF does not contribute to chronic leukocyte activation and, consequently, does not place ESRD patients at greater risk with respect to inflammatory morbidity and mortality.

Adult↗