Biomedical subjects

Jenny Larsson

Publications and source records attributed to Jenny Larsson.

4 recordsLinked to original sources

PubMed2004

Anti-inflammatory effects of a titanium-peroxy gel: role of oxygen metabolites and apoptosis.

Polymorphonuclear neutrophils (PMN) are among the first inflammatory cells to arrive at an implant interface, where they encounter with the foreign material and may produce reactive oxygen species (ROS). During the interaction between titanium and ROS, titanium-peroxy (Ti-peroxy) compounds may be formed. We used a Ti-peroxy gel, made from titanium and hydrogen peroxide, to study the effects of Ti-peroxy compounds on PMN. In the absence of serum, the Ti-peroxy gel decreased the oxidative response of PMN to yeast and PMA and reduced PMN apoptosis without inducing necrosis. These effects could not be ascribed to the release of hydrogen peroxide from the Ti-peroxy gel, because a steady-state hydrogen peroxide producing system failed to mimic the effects of the gel. The effects were similarly unaffected when PMN were preincubated with beta(2)-integrin antibodies, questioning the involvement of adhesion molecules. Nevertheless, when a filter was used to separate the Ti-peroxy gel from the cells, the gel effect on PMN life span was abolished, pointing to a contact-dependent mechanism. In the presence of serum, the Ti-peroxy gel had no effect on the PMN oxidative response and life span, but appeared rather inert. In summary, this study demonstrates that the Ti-peroxy gel has potentially anti-inflammatory properties through a combined peroxide and physical contact effect, supporting the notion that interactions between titanium and inflammatory cells are responsible for the good performance of titanium in vivo.

Anti-Inflammatory Agents↗

PubMed2004

Staphylococcus aureus, but not Staphylococcus epidermidis, modulates the oxidative response and induces apoptosis in human neutrophils.

S. epidermidis is the most common isolate in foreign body infections. The aim of this study was to understand why S. epidermidis causes silent biomaterial infections. In view of the divergent inflammatory responses S. epidermidis and S. aureus cause in patients, we analyzed how they differ when interacting with human neutrophils. Neutrophils interacting with S. epidermidis strains isolated either from granulation tissue covering infected hip prostheses or from normal skin flora were tested by measuring the oxidative response as chemiluminescence and apoptosis as annexin V binding. Different S. aureus strains were tested in parallel. All S. epidermidis tested were unable to modulate the oxidative reaction in response to formyl-methionyl-leucyl-phenylalanine (fMLP) and did not provoke, but rather inhibited, apoptosis. In contrast, some S. aureus strains enhanced the oxidative reaction, and this priming capacity was linked to p38-mitogen-activated-protein-kinase (p38-MAPK) activation and induction of apoptosis. Our results may explain why S. epidermidis is a weak inducer of inflammation compared to S. aureus, and therefore responsible for the indolent and chronic course of S. epidermidis biomaterial infections.

Annexin A5↗

PubMed2002

Evaluation and optimization of two complementary cross-flow ultrafiltration systems toward isolation of coastal surface water colloids.

While colloidal phases in natural waters are important to the speciation and bioavailability of trace metals and organic compounds, accurate isolation of these submicron entities from their lower molecular-weight counterparts has proved challenging. Here, both laboratory and field experiments have been conducted to constrain integrity aspects of two different cross-flow filtration (CFF) systems. We tested both a commonly applied 5000 cm2 CFF system (Pellicon2, Millipore; manufacturer-specified 1 and 3 kDa cutoff) and a less studied mini-CFF system with a 50 cm2 membrane area (Pellicon Lab Scale XL, Millipore; with 5, 10, 100, and 1000 kDa cutoff). A natural water matrix amended with a series of fluorescently tagged colloidal probes was employed to demonstrate that a cross-flow ratio (CFR; retentate-to-permeate flux) > 15 was required for both of these systems to obtain high recoveries of colloids. Contrary to previous calibrations of CFF, also at colloid concentrations characteristic of natural waters, the established retention profiles for the colloid probes on these systems, when operated under CFR > 15, affirmed the manufacturer-specified cutoff values (in parentheses): 2.4 kDa (1 kDa), 3.3 kDa (3 kDa), 6.1 kDa (5 kDa) and 8.7 kD (10 kDa). A concentration factor (cf) > 10 was found necessary for the reliable determination of the colloidal pool of several elements in the surface waters of the open Baltic Sea. Application of CFR > 15 and cf > 10 returned recoveries around 100% for the studied organic carbon, Ca, Mo, Fe, Cu, and Ni on both systems. Furthermore, the trend of colloid association for the transition elements in the offshore Baltic surface waters followed expectations from their Irving-Williams series of coordination chemistry.

Biological Availability↗

PubMedDate not supplied

Surface-assisted delivery of fluorescent groups to hGST A1-1 and a lysine mutant.

Human glutathione transferase (hGST) A1-1 and a lysine mutant (A216K) can both be rapidly and site-specifically acylated on Y9 and K216, respectively, using a range of thiolesters of glutathione (GS-thiolesters) as modifying reagents. The present investigation was aimed at developing a method with which to deliver a fluorescent acyl group from a solid support under conditions compatible with standard protein purification schemes. A number of fluorescent GS-thiolesters with modified peptide backbones were therefore prepared and tested for reactivity toward hGST A1-1 and the A216K mutant. Substitutions at the alpha-NH2 part of the glutathione backbone were not tolerated by the proteins. However, two fluorescent reagents that carry a biotin moiety at the C-terminal part of glutathione were found through MALDI-MS experiments to react in solution with Y9 of the wild-type protein and one reagent with K216 of A216K. The reaction can take place in the presence of glutathione and even in a crude E. coli lysate of cells expressing A216K. Delivery of the fluorescent group to Y9 or K216 was possible using NeutrAvidin (NA) beads that had been preincubated with biotinylated reagent. Alternatively, excess reagent can be removed by a brief incubation with NA beads. We have thus now developed a system for protein labeling with easy removal of excess and used up low-molecular weight reagent. This strategy can conceivably be utilized in future protein purification and labeling experiments.

Esters↗