| 61. |
- Thorslund, Sara, et al.
(författare)
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Functionality and stability of heparin immobilized onto poly(dimethylsiloxane)
- 2005
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 45:2, s. 76-81
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Tidskriftsartikel (refereegranskat)abstract
- Poly(dimethylsiloxane) (PDMS) has become an attractive material when working in the field of microfluidics, mainly because of the rapid prototyping process it involves. The increased surface volume ratio in microchannels makes the interaction between sample and material surface highly important, evident when handling complex biological samples such as plasma or blood. This study demonstrates a new grade of non-covalent heparin surface that adds efficient anticoagulant property to the PDMS material. The surface modification is a simple and fast one-step process performed at neutral pH, optimal when working with closed microsystems. The heparin formed a uniform and functional coating on hydrophobic PDMS with comparatively high level of antithrombin-binding capacity. In addition, long-term studies revelaed that the immobilized heparin was more or less stable in the microchannels over a time of three weeks. Recalcified plasma in contact with native PDMS showed complete coagulation after 1 h, while no fibrin formation was detected in plasma incubated on heparin-coated PDMS within the same time. In conclusion, we see the heparin coating developed and evaluated in this study as a tool that greatly facilitates the use of PDMS in microfluidics dealing with plasma or blood samples.
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| 62. |
- Trulson, Agneta, et al.
(författare)
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The functional heterogeneity of eosinophil cationic protein is determined by a gene polymorphism and post-translational modifications
- 2007
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 0954-7894 .- 1365-2222. ; 37:2, s. 208-218
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Tidskriftsartikel (refereegranskat)abstract
- Background The eosinophil is a cytotoxic cell and takes part in parasite killing and tissue-destructive processes by secretion of proteins such as eosinophil cationic protein (ECP). A polymorphism was demonstrated in the ECP gene, giving rise to a substitution of arginine at position 97 with threonine. This polymorphism is related to disease development. Objective To investigate the functional and molecular heterogeneity of native ECP and the functional consequences of the replacement of arginine with a threonine. Methods ECP was purified from healthy blood donors by gel filtration, ion-exchange chromatography and reversed-phase chromatography. Recombinant ECPs i.e. rECP 97arg and rECP 97thr were produced by the pFASTBAC baculovirus expression system. The cytotoxic activity was determined against an erythroleukaemia or a small cell lung cancer cell line. Results Native ECP was purified to apparent homogeneity and showed a considerable molecular heterogeneity and a corresponding functional heterogeneity with respect to cytotoxic activity. After reduction, the native cytotoxic ECP showed three bands on sodium dodecylsulphate polyacrylamide gel electrophoresis: one major band at 18-20 kDa and two minor bands at about 10 and 5 kDa, respectively. The 5 kDa contained two masses differing with 56.2 Da, which corresponds to the difference in molecular masses of arginine and threonine. rECP 97arg was cytotoxic in contrast to rECP97thr. Deglycosylation with N-glycosidase F did not affect the cytotoxic activity of native ECP to any measurable extent nor the activity of rECP 97arg, whereas rECP 97thr achieved cytotoxic activity. The RNase activities of the recombinant and native ECPs were similar. Conclusion We conclude that ECP is present in several molecular forms with varying biological activities. Some of this functional heterogeneity is based on the genetic polymorphism of the ECP gene and some on post-translational modifications. In subjects carrying the ECP 97thr variant, the cytotoxic activity may be disguised by N-linked glycosylation of the active site.
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| 63. |
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| 64. |
- Vik, Anders, et al.
(författare)
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Antimicrobial and cytotoxic activity of agelasine and agelasimine analogs
- 2007
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Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 15:12, s. 4016-4037
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Tidskriftsartikel (refereegranskat)abstract
- Agelasine and agelasimine derivatives with substantially less complicated terpenoid side chains compared to the naturally occurring compounds have been synthesized and their ability to inhibit growth of microorganisms and cancer cells has been studied. Compounds with excellent activity against cancer cell lines (MIC ca. 1 μM for the most potent compounds), including a drug resistant renal cell line, have been identified. Most compounds studied also exhibited broad spectrum antimicrobial activity including activity against Mycobacterium tuberculosis.
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| 65. |
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| 66. |
- Westerlund, Joakim, et al.
(författare)
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A note on the pooling of individual panic unit root tests
- 2009
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Ingår i: Econometric Theory. - 0266-4666 .- 1469-4360. ; 25:6, s. 1851-1868
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Tidskriftsartikel (refereegranskat)abstract
- One of the most cited studies in recent years within the field of nonstationary panel data analysis is that of Bai and Ng (2004), in which the authors propose PANIC, a new framework for analyzing the nonstationarity of panels with idiosyncratic and common components. The problem is that the asymptotic validity of PANIC as a platform for constructing pooled panel unit root tests based on averaging is not fully proven. This paper provides the required results, whose usefulness is verified through simulations.
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| 67. |
- Wiberg, Kristina, et al.
(författare)
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In vitro activity of bortezomib in cultures of patient tumour cells-potential utility in haematological malignancies
- 2009
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Ingår i: Medical Oncology. - : Springer Science and Business Media LLC. - 1357-0560 .- 1559-131X. ; 26:2, s. 193-201
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Tidskriftsartikel (refereegranskat)abstract
- Bortezomib represents a new class of anti-cancer drugs, the proteasome inhibitors. We evaluated the in vitro activity of bortezomib with regard to tumour-type specificity and possible mechanisms of drug resistance in 115 samples of tumour cells from patients and in a cell-line panel, using the short-term fluorometric microculture cytotoxicity assay. Bortezomib generally showed dose-response curves with a steep slope. In patient cells, bortezomib was more active in haematological than in solid tumour samples. Myeloma and chronic myeloid leukaemia were the most sensitive tumour types although with great variability in drug response between the individual samples. Colorectal and kidney cancer samples were the least sensitive. In the cell-line panel, only small differences in response were seen between the different cell lines, and the proteasome inhibitors, lactacystin and MG 262, showed an activity pattern similar to that of bortezomib. The cell-line data suggest that resistance to bortezomib was not mediated by MRP-, PgP, GSH-; tubulin and topo II-associated MDR. Combination experiments indicated synergy between bortezomib and arsenic trioxide or irinotecan. The data support the current use of bortezomib but also points to its potential utility in other tumour types and in combination with cytotoxic drugs.
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| 68. |
- Wickström, Malin, et al.
(författare)
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Pharmacological profiling of disulfiram using human tumor cell lines and human tumor cells from patients
- 2007
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Ingår i: Biochemical Pharmacology. - : Elsevier BV. - 0006-2952 .- 1356-1839. ; 73:1, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- The thiocarbamate drug disulfiram has been used for decades in the treatment of alcohol abuse. Disulfiram induces apoptosis in a number of tumor cell lines and was recently by us proposed to act as a 26S proteasome inhibitor. In this work we characterized disulfiram in vitro with regard to tumor-type specificity, possible mechanisms of action and drug resistance and cell death in human tumor cell lines and in 78 samples of tumor cells from patients using the fluorometric microculture cytotoxicity assay and the automated fluorescence-imaging microscope ArrayScan®. Disulfiram induced cytotoxicity in a biphasic pattern in both cell lines and patient tumor cells. Disulfiram induced apoptosis as measured by cell membrane permeability, nuclear fragmentation/condensation and caspase-3/7 activation using high content screening assays. For many of the cell lines tested disulfiram was active in sub-micromolar concentrations. When comparing the log IC50 patterns with other cytotoxic agents, disulfiram showed low correlation (R < 0.5) with all drugs except lactacystin (R = 0.69), a known proteasome inhibitor, indicating that the two substances may share mechanistic pathways. Disulfiram was more active in hematological than in solid tumor samples, but substantial activity was observed in carcinomas of the ovary and the breast and in non-small cell lung cancer. Disulfiram also displayed higher cytotoxic effect in cells from chronic lymphocytic leukemia than in normal lymphocytes (p < 0.05), which may indicate some tumor selectivity. These results together with large clinical experience and relatively mild side effects encourage clinical studies of disulfiram as an anti-cancer agent.
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| 69. |
- Wickström, Malin, 1978-
(författare)
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Preclinical Studies of the Melphalan Prodrug J1 for Cancer Therapy
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- J1 (L-melphalanyl-L-p-fluorophenylalanyl ethyl ester) is a dipeptide derivative of the alkylating agent melphalan with increased cytotoxicity. In this thesis the preclinical pharmacology of J1 has been characterized.Our results show that J1 rapidly enters the cells, where melphalan is released by hydrolysis. The maximum concentration (Cmax) of melphalan was detected 15 min after exposure to J1 in human cancer cell lines. In comparison, melphalan exposure resulted in a 10-fold lower Cmax that was shifted to later time points. J1 induced more DNA damage and apoptosis than melphalan. The cytotoxic activity and release of melphalan from J1 were inhibited by preincubating cells with the aminopeptidase inhibitor bestatin. In accordance with these results, we showed that J1 is a substrate for aminopeptidase N (APN), which may result in increased tumor selectivity.J1 effectively inhibited cell growth in a set of neuroblastoma cell lines. Athymic mice carrying neuroblastoma xenografts were treated either with equimolar doses of melphalan or J1. J1 inhibited the tumor growth more effectively than melphalan and the untreated control, and was associated with higher caspase-3 activation, fewer proliferating tumor cells and decreased mean vascular density.J1 and melphalan showed similar activity profiles when tested in 176 primary tumor cell cultures from patients, but J1 exhibited 50- to 100-fold higher potency. The difference was greater in some diagnoses (e.g. breast cancer, NHL and AML), and was exceptionally large in some breast cancer samples with aggressive phenotypes. A combination screening of J1 and standard chemotherapeutics yielded mostly additive interactions, except for etoposide which induced synergy in all tested cell lines.In conclusion, the melphalan prodrug J1 is effectively transported into the cells, where aminopeptidases (for example APN) catalyze the formation of melphalan. J1 shows promising preclinical potential in the diagnoses neuroblastoma and breast cancer.
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| 70. |
- Wickström, Malin, et al.
(författare)
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The novel alkylating prodrug J1: diagnosis directed activity profile ex vivo and combination analyses in vitro
- 2008
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Ingår i: Investigational new drugs. - : Springer Science and Business Media LLC. - 0167-6997 .- 1573-0646. ; 26:3, s. 195-204
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The dipeptide J1 acts as a prodrug of melphalan with a significant increased potency in vitro resulting from activation by cellular aminopeptidases. The current study was performed to evaluate the ex vivo profile of J1 using 176 primary tumor cell cultures from patients. In addition, the activity of J1 in combination with eight standard drugs, representing different mechanistic classes, was studied in nine different human tumor cell lines of different histopathological origin. Methods: Ex vivo evaluation of tumor type selectivity, was performed using the established fluorometric microculture cytotoxicity assay (FMCA). Combinations between J1 and eight standard chemotherapeutic drugs were analyzed using the median-effect method. Results: The prodrug J1 expressed approximately 50- to 100-fold higher potency but similar activity profile as that of its metabolite, melphalan. The difference was greater in some diagnoses (e.g. breast cancer, NHL and AML), and exceptionally high in some breast cancer samples with aggressive phenotypes. Combination analysis of J1 and standard chemotherapeutics yielded several potentially additive and synergistic interactions, most striking for etoposide with significant synergism in all studied cell lines. Conclusions: In conclusion, the ex vivo profile suggests that further evaluation of J1 as the alkylating agent in for example aggressive breast cancer might be of particular interest, preferentially in combination with DNA-topoisomerase II inhibitors like etoposide.
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