Biomedical subjects

A Urbanska

Publications and source records attributed to A Urbanska.

5 recordsLinked to original sources

PubMed2005

Investigation of a new microcapsule membrane combining alginate, chitosan, polyethylene glycol and poly-L-lysine for cell transplantation applications.

Microencapsulation of living cells may serve as an alternative therapy for patients requiring organ transplants. One of the limiting factors in the progress of such therapy is attaining a biocompatible and mechanically stable polymer. The current study investigates the potential of a novel membrane combining alginate, chitosan, polyethylene glycol (PEG) and poly-L-lysine (PLL) with the objective of proposing a membrane suitable for cell entrapment that may overcome some of the shortcomings of the widely studied alginate-poly-L-lysine-alginate (APA) capsules. The novel microcapsule was formulated using a 1.5% alginate solution coated with 0.05% chitosan, 0.1% PEG and 0.05% poly-L-lysine with a final layer of 0.1% alginate. Microcapsules having a diameter of 450 +/- 30 microm were prepared. Upon citrate treatment, the membrane remained intact and retained its spherical structure. The membrane was able to support liver cell proliferation and the encapsulated cells were capable of secreting proteins. The study demonstrated that the new membrane can be used for cell entrapment. However, further investigations are needed to assess its potential for long term transplantation and usage in the development of bioartificial organs.

Albumins↗

PubMed1987

UV-irradiated epidermal cells produce a specific inhibitor of interleukin 1 activity.

UV irradiation of epidermal cells (EC) in vitro and in vivo leads to an enhanced synthesis of the immunostimulating cytokine interleukin 1 (IL 1). However, UV exposure in vivo also results in local as well as systemic immunosuppression. Therefore, it was tested whether UV-exposed murine EC in culture in addition to IL 1 release an inhibitor of IL 1 activity. Supernatants of UV-irradiated BALB/c EC and of a transformed keratinocyte cell line (Pam 212) were evaluated for their ability to suppress IL 1-mediated thymocyte proliferation. Crude supernatants derived from either UV-exposed or unirradiated EC did not interfere with IL 1 activity. When supernatants were subjected to HPLC gel filtration, fractions eluting at approximately 40 kD significantly blocked the activity of EC-derived IL 1 and murine recombinant IL 1. The release of this inhibitory cytokine (EC-derived contra-IL 1 [EC-contra-IL 1]) was confined to UV-exposed BALB/c or Pam 212 keratinocytes, since no inhibitory activity was detected in supernatants of unirradiated cells. EC-contra-IL 1 also blocked IL 1-induced fibroblast proliferation but did not suppress IL 2 or IL 3 activity. Moreover, EC-contra-IL 1 did not inhibit spontaneous proliferation of a variety of cell lines (Pam 212, P388D1, L 929, EL 4). With the use of chromatofocusing EC-contra-IL 1 exhibited a pI of 8.8, and upon reversed-phase chromatography it eluted within three distinct peaks. Therefore, murine UV-exposed EC, in addition to the production of immunoenhancing cytokines, also may release immunosuppressing mediators and thereby participate in UV-induced immunosuppression. These findings further support the notion that the epidermis may not only be considered as a simple barrier against harmful agents but represents an active element of the immune system.

Animals↗

PubMed1987

Blood-membrane interaction in hemodialysis leads to increased cytokine production.

Recently much interest has been focused on the role of immunoregulatory cytokines such as interleukin 1 (IL 1) and interleukin 2 (IL 2) during the pathogenesis of immunological as well as inflammatory diseases. Therefore peripheral blood mononuclear cells (PBMC) of eight patients undergoing hemodialysis (HD) were tested for IL 1 and IL 2 production. Before starting HD, cytokine production by PBMC in culture was not altered in comparison to normal healthy controls, however, a significant increase of IL 1 and IL 2 production was observed within the first HD hour which lasted throughout the end of HD. Moreover direct effects of cellulose membranes on PBMC cytokine production as well as serum IL 1 levels have been investigated. Serum IL 1 levels were already elevated before onset of HD and increased further during HD. The discrepancy between PBMC IL 1 production and serum IL 1 levels may be due to the diminished excretion in patients with end-stage renal disease. Since addition of dialysis membrane particles enhanced monocytes to produce more IL 1 as well as lymphocytes to release more IL 2, a direct stimulatory membrane effect is postulated. The increased release of immunoregulatory cytokines may account for some of the pathologic findings observed during hemodialysis.

Adult↗

PubMed1986

Inhibition of the induction of contact hypersensitivity by a UV-mediated epidermal cytokine.

UVB exposure (290-320 nm) of mice has been shown to cause systemic suppression of contact hypersensitivity (CHS). Because UVB radiation hardly penetrates the epidermis, epidermal cells have been anticipated to be the site of the initiation of immunosuppression. Supernatants derived from UV-irradiated BALB/c epidermal cell cultures and a keratinocyte cell line (Pam 212) were evaluated for the ability to induce suppression of CHS after i.v. injection to BALB/c mice. Injection of supernatants derived from UV-treated epidermal cells and Pam 212 cells significantly blocked induction but not elicitation of CHS. In contrast, i.v. application of supernatants derived from unirradiated cells did not inhibit CHS. Using high-performance liquid chromatography gel filtration this mediator was shown to be a low-molecular-weight protein (15-50 kD). Moreover UV-mediated inhibitor production seems to be confined to epidermal cells since neither P 388 macrophages nor L 929 fibroblasts released this inhibitory cytokine. Therefore UV radiation may induce epidermal cells to produce an inhibitor of CHS which is distinct from prostaglandins and leukotrienes and may participate in the regulation of UV-mediated local as well as systemic immunosuppression.

Animals↗

PubMed1977

Nucleoprotein chromatin subunit from Physarum polycephalum.

The nucleoproteins resulting from digestion of the nuclei of the true slime mold Pysarum polycephalum with micrococcal nuclease have been resolved according to the size classes in linear sucrose gradients containg 0.5 M NaCl, and analysed for DNA, RNA and protein content. The basic nucleoprotein subunit has been found to contain a DNA fragment of about 150--170 base pairs complexed with an approximately equal amount, on a weight basis, of basic proteins and a relatively small amount of non-histone proteins (about 35% of the amount of DNA). Higher nucleoprotein oligomers were shown to contain spacer DNA fragments between adjacent subunits and a considerably higher ratio of non-histone proteins to DNA than the basic subunit. Both the basic subunit and higher nucleoprotein oligomers of Physarum chromatin contain some amount of tightly bound RNA. However, in contrast to the distribution of the non-histone proteins, the ratio of RNA to RNA is similar in both fractions.

Chromatin↗