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Biomedical subjects

E Pålsson

Publications and source records attributed to E Pålsson.

8 recordsLinked to original sources
PubMed2001

Theories of chromatographic efficiency applied to expanded beds.

Various quantities such as plate height (HETP), number of plates (N), axial dispersion coefficient (Dax) and Bodenstein number (Bo) are used to describe the efficiency of, and dispersion in chromatographic columns. Different quantities highlight different aspects of the performance. Due to the expansion of expanded-bed columns, the information contained in some of these quantities is not the same for expanded beds as for packed beds. In this article the mentioned quantities are described and discussed both theoretically and related to experimental data. It is concluded that they are often used in a confusing way. Quantities modified to be more informative when comparing beds of different expansions are developed (N(EB) = N/expansion2 and HETP(EB) = HETP x bed expansion) and recommendations of which quantity to use in what situation are given.

Chromatography↗
PubMed2000

Pellicular expanded bed matrix suitable for high flow rates.

A new type of expanded bed matrix with a heavy core of stainless steel covered with an agarose layer was prepared. Two bead size fractions, the smaller one (32-75 microm diameter) having a single particle core and the larger (75-180 microm diameter) with an agglomerate of stainless steel particles constituting the core, were chosen for further characterisation. The dispersion behaviour was determined both in packed bed and expanded bed modes by the retention time distribution method (RTD) and compared with the Streamline matrix (Amersham Pharmacia Biotech). The comparison turned out in favour of the new matrix. Flow rates as high as 3000 cm/h were used with the larger fraction, giving stable expanded beds with good mass transfer properties. The matrices were mechanically stable without any tendency to crack or peal, even after prolonged use.

Chromatography, Liquid↗
PubMed2000

Superporous agarose monoliths as mini-reactors in flow injection systems. On-line monitoring of metabolites and intracellular enzymes in microbial cultivation processes.

A new type of agarose material, superporous agarose, was used as a support material in an analytical system designed for monitoring of bioprocesses with respect to metabolites and intracellular enzymes. The superporous agarose was used in the form of miniaturised gel plug columns (15 x 5.0 mM I.D. monolithic gel bed). The gel plugs were designed to have one set of very large pores (about 50 microm in diameter) through which cells, cell debris and other particulate contaminants from the bioreactor could easily pass. The material also had normal diffusion pores (300 A) characteristic of all agarose materials, providing ample surface for covalent attachment of antibodies and enzymes used in the analytical sequence. The superporous agarose gel plug columns were characterised with respect to flow properties and handling of heavy cell loads as well as dispersion of injected samples (a Bodenstein number of about 40 was observed with acetone tracer at a flow rate of 1 ml min(-1)). To evaluate the practical performance of the superporous gel plug columns, two applications were studied: (1) on-line determination of glucose in cultivation broth (gel plug with immobilized glucose oxidase) and (2) immunochemical quantification of intracellular beta-galactosidase in E. coli (gel plug with lysozyme to achieve cell lysis and gel plug with antibodies against beta-galactosidase).

Bioreactors↗
PubMed2000

Locus-specific multifluor FISH analysis allows physical characterization of complex chromosome abnormalities in neoplasia.

Novel techniques in molecular cytogenetics have radically improved the ability to characterize genetic changes in neoplastic cells. In parallel, a rapid development in high-throughput genomics has resulted in detailed physical maps of the human genome. Combining these two fields, we have developed a method for the simultaneous visualization of several physically defined segments along a chromosome. Seven YAC clones and one subtelomeric cosmid clone from chromosome 12 were labeled with unique combinations of four fluors and hybridized to metaphase chromosomes from neoplastic cells. In a uterine leiomyoma and a myxoid liposarcoma with translocations 12;14 and 12;16, the breakpoints in chromosome 12 could be localized to the HMGIC and CHOP regions, respectively. In the other tumors, more complex aberrations were visualized, including two inversions in 12q with a common breakpoint between MDM2 and D12S332 in a pleomorphic adenoma, amplification of MDM2 and CDK4 in ring chromosomes from a malignant fibrous histiocytoma, and amplification of KRAS2 together with other unbalanced rearrangements in two pancreatic adenocarcinomas. Combinatorially labeled single-copy probes may thus simultaneously provide physical localization of breakpoints and an overview of complex structural rearrangements. Genes Chromosomes Cancer 28:347-352, 2000.

Chromosome Aberrations↗
PubMed1999

Faster isolation of recombinant factor VIII SQ, with a superporous agarose matrix.

A superporous agarose matrix was compared with a corresponding homogenous matrix in the isolation of recombinant factor VIII SQ (r-VIII SQ) by immunoaffinity chromatography. As a reference, the commercially available Sepharose FastFlow, used for a similar purification in the industry, was also evaluated. Breakthrough curves are described for flows between 50 and 400 cm/h with pre-purified r-VIII SQ and with cell culture broth. The superporous gel gave the best performance and a 1000-fold purification was obtained in a one-step procedure. The superporous matrix made it possible to increase the throughput about four-fold, presumably due to its better mass transfer properties. The importance of the ligand distribution profile is discussed based upon immunofluorescence microscopy data.

Chromatography, Affinity↗
PubMed1997

Clonal chromosome aberrations are present in vivo in synovia and osteophytes from patients with osteoarthritis.

We have previously reported recurrent clonal chromosomal aberrations in synovia, osteophytes and articular cartilage from patients with osteoarthritis (OA). In particular, gain of chromosomes 5 and 7 was found to be strongly associated with OA. In order to exclude the possibility of in vitro artefacts, we studied three to four parallel, independent cultures from ten samples of synovia and three samples of osteophytes from ten women with primary OA. In all, 40 cultures were cytogenetically analysed, 39 of which had clonal chromosomal aberrations. The most common aberrations were +7 and +5 which were found in 38 and 12 cultures, respectively. There were striking karyotype similarities among the parallel cultures from each case. Out of a total of 83 clones, only 11 were unique for one culture, 7 from synovia and 4 from osteophytes. The genetic homogeneity among different cultures from the same patients excludes the possibility of in vitro artefacts and indicates a widespread distribution of the cytogenetically aberrant clones in vivo.

Aged↗
PubMed1996

Evidence of somatic mutations in osteoarthritis.

We examined, cytogenetically and by in situ hybridization (ISH) techniques, the synovia, osteophytes, and articular cartilage from 32 patients with pronounced osteoarthritis (OA), a prevalent form of arthropathy characterized by progressive reduction of articular cartilage, and synovial samples from 17 control patients. In short-term cultures, clonal chromosome aberrations, in particular the gain of chromosomes 7 (+7) and 5 (+5), were found to be strongly associated with OA. These aberrations were found in almost 90% of the cultures from synovia and osteophytes, whereas only 1/11 synovial samples from joints unequivocally unaffected by OA had cells with +5 or +7. The in vivo nature of trisomy 7 was demonstrated by ISH on uncultured cells, and serial passaging showed that cells with +7 had a proliferative advantage in vitro. Thus, the combined data indicate that cells with somatic mutations appear early and may be influential in the disease process leading to OA.

Adult↗