PubMed Health⌕ Search

Biomedical subjects

I Lundström

Publications and source records attributed to I Lundström.

At least 55 records · Page 3Linked to original sources
PubMed1996

Complement activation by IgG immobilized on methylated silicon.

Activation of the complement system by immobilized IgG on methylated silicon was studied by ellipsometry/antibody-, ELISA-, and RIA techniques after exposure to human serum at 37 degrees C for up to 1 h. The IgG-covered surfaces rapidly activated the complement system and the combined results suggest an initial classical pathway activation. Complement factor 1q (C1q) and IgG were antibody-detectable on the surfaces for serum incubations up to 5 min but not thereafter. Anti-C3c and anti-properdin bound to the surfaces at all serum incubation times. Experiments with 125I-IgG preadsorbed to surfaces, or added to normal-, EGTA-, and EDTA-sera, showed that IgG was not displaced from the protein film by serum.

CD4 Antigens↗
PubMed1996

Platelet binding and protein adsorption to titanium and gold after short time exposure to heparinized plasma and whole blood.

Protein adsorption from human plasma and platelet binding and activation were studied at short blood-titanium/gold contact times. The protein adsorption was studied by ellipsometry-antibody techniques in situ, and adhering platelets were visualized with fluorescein isothiocyanate-labelled anti-CD 61 antibodies. Adhering platelets were quantified by counting labelled cells in microscopic image fields. The spreading of platelets was studied by scanning electron microscopy. The results show that after 1 min of plasma exposure, fibrinogen, IgG and albumin were detectable with antibodies on both surfaces. The amount of deposited fibrinogen and complement decreased with time on titanium, and the amount of adsorbed anti-high molecular weight kininogen increased. No complement was detected on gold surfaces after plasma incubation, and the antibody binding pattern also remained unchanged after prolonged plasma exposure. The surface-bound platelets were found to spread on the gold but not on titanium surfaces. C1q has been shown to induce the expression of P-selectin, i.e. cause secretion reactions in platelets. In this study secreted platelet-microvesicles were found on gold, but not on the titanium surfaces that bound significant amounts of C1q. Thus, the results of the present study indicate that the mixture of fibrinogen, C1q and kininogens, whilst causing adhesion and aggregation, does not result in the activation and microvesicle secretion of platelets. Platelet activation on biomaterial surfaces thus seems to be governed by the mixture of proteins present on that surface, and no one particular protein need cause a known reaction in platelets as obtained when platelets are exposed only to that particular protein.

Adsorption↗
PubMed1996

Complement activation by 3-mercapto-1,2-propanediol immobilized on gold surfaces.

Thiol-modified surfaces are chemically well defined and suited for surface biological model experiments and biomaterials research. 3-Mercapto-1,2-propanediol (mercaptoglycerol, MG), immobilized on gold, spontaneously binds immunoglobulins from human serum and activates the complement system. The surface-bound complement factors were detected by ellipsometry-antibody techniques. The overall complement activation was subsequently corroborated independently with enzyme immunosorbent assay (EIA) and sheep and chicken erythrocyte haemolytic complement techniques. EIA experiments indicated elevated levels of C4d, but no significant increase of factor Bb was evident in the test serum from the MG system. The haemolytic assays show that MG surfaces consume complement factors from both pathways. Ellipsometry revealed that immunoglobulin G (IgG) and complement factor 1q (C1q) are transiently antibody detectable on MG after exposure to whole serum by the use of antibody techniques. Complement factor 3 (C3), C2, C4 and properdin could be detected on the surface, but not factors H and B. The total adsorbed mass and particularly C3 antibody deposition were suppressed by using EGTA-Mg2+ serum. The results suggest that MG surfaces initially activate complement via the classical pathway. Other IgG binding surfaces also appear to behave in a similar manner.

Animals↗
PubMed1996

Blood protein interactions with titanium surfaces.

Protein adsorption and complement activation were studied on thin evaporated films of titanium (Ti). The surfaces were cleaned in either a radio frequency (RF) plasma unit, or washed sequentially in trichloroethylene, acetone, ethanol, and water. Both methods resulted in hydrophilic surface with low carbon contamination on the outermost oxide (approximately 11-13 at%). In situ ellipsometry suggested that Ti is an intrinsic coagulation activator in vitro, since significant amounts of factor XII (F XII) and high molecular weight kininogen (HMWK) were found on the surfaces after 1 min incubation in heparin plasma. Ellipsometry, performed after serum incubations ranging from 15 s to 30 min showed that the total amount of serum proteins and the deposition of antibodies to complement factor 3c (C3c) increased with serum incubation time. ELISA methods showed increased levels of free iC3b in serum after 10 min incubation of the surfaces, but no detectable amounts of C3 convertase fractions C4d or Bb. Ellipsometric results indicated, however, an increased deposition of antibodies to CIq and IgG on Ti after short serum incubation times. The combined results indicate that Ti-surfaces initially activate complement through the classical pathway. The activation then continues via a positive amplification loop where increased amounts of C3 are deposited on the surfaces via the alternative pathway.

Acetone↗
PubMed1996

Blood protein interactions with chromium surfaces.

Protein adsorption, contact activation, and complement activation were studied on thin evaporated films of chromium (Cr) in vitro. The surfaces were, prior to the experiments, cleaned in either ethanol and water, or in a basic peroxide solution (RCA standard clean 1, SC-1). Surface spectroscopic studies of the outermost oxides showed a significant reduction of carbon contaminants after washing in SC-1 but also suggested an increase in the oxidation state as compared with the ethanol-washed surfaces. In situ ellipsometry combined with antibody techniques was used to determine protein deposition and antibody binding onto surfaces after incubations in heparin plasma or in normal serum. Incubation times from 1 to 10 min in serum showed increased depositions of serum and antibodies to complement factor 3c (C3c) and was larger on ethanol-washed surfaces than on surfaces washed in SC-1. ELISA methods indicated increased amounts of iC3b in serum for both surfaces, but no presence of C3 convertases (C4d or Bb fractions). A low or transient complement activation via the classical pathway was indicated on ethanol washed Cr, since deposition of secondary antibodies to complement factor Iq (CIq) was observed only after short incubation times in serum. No procoagulant activity of Cr was indicated, since only low amounts of antibodies to factor XII (F XII), prekallikrein (PKK), and high molecular weight kiniogen (HMWK) bound to the surfaces after incubations in heparin plasma. These results were confirmed using a colorimetric assay where the relative amounts of free plasma kallikrein was assessed using a chromogenic substrate, H-D-Pro-Phe-Arg-pNA (S-2302).

Adsorption↗
PubMed1995

A biosensor concept based on imaging ellipsometry for visualization of biomolecular interactions.

A new type of optical biosensor system is proposed and its application to detection of antigen-antibody complexes on a silicon substrate is demonstrated. The biosensor system is utilizing specificities of biomolecular interactions in combination with protein patterned surfaces. Visualization of the thickness distributions of thin layers (protein patterns) on a surface is achieved by using imaging ellipsometry. This technique uses a CCD camera whereby an ellipsometric analysis of a large surface can be made. The biosensor system has the advantages of high spatial resolution, fast data acquisition, and simplicity in use.

Adsorption↗
PubMed1995

Biosensing with surface plasmon resonance--how it all started.

A subjective description is given of how the development of surface plasmon resonance for immunosensing began. The main differences between the initial experiments and a commercially available instrumentation are pointed out. For the practical use of surface oriented methods for biosensing it is noted that the arrangements around the optical system itself, such as the sensing chip or sample cell, are most important. It is concluded that the instrumentation developed can be used not only for immunosensing but also for "real time biospecific interaction analysis" in general. It is pointed out that the use of surface plasmon resonance for detection is only one possibility and that many new (optical) methods for real time biospecific interaction analysis have been and will be developed.

Biosensing Techniques↗
PubMed1994

In vitro plasma protein adsorption and kallikrein formation on 3-mercaptopropionic acid, L-cysteine and glutathione immobilized onto gold.

3-Mercaptopropionic acid (MPA), L-cysteine (L-cys), and glutathione (GSH) monolayers were immobilized onto gold and used in in vitro protein tests. The surfaces were characterized with ellipsometry, static contact angle measurements, atomic force microscopy, and Fourier transform infrared reflection absorption spectroscopy (FT-IRAS). After incubations in human plasma and antibody solutions, the surface antisera binding patterns were determined with ellipsometry. Using serum instead of plasma, complement activation was studied in the same fashion. Activated coagulation Factor XII and kallikrein formation on the surfaces and in the plasma were studied using a kallikrein-specific colorimetric assay. 3-Mercaptopropionic acid indicated contact activation of coagulation but L-cysteine did not. Glutathione displayed low deposition of plasma proteins, large deposition of proteins from serum, and did not promote kallikrein formation. None of the surfaces could be attributed complement activating properties, as determined by antibody deposition. The present study demonstrates that surface biology in complex model systems can be conveniently studied in vitro through systematic and well defined surface modifications.

3-Mercaptopropionic Acid↗
PubMed1994

Differential surface binding of albumin, immunoglobulin G and fibrinogen.

Protein-protein interactions, as well as the nature of the surface, significantly affect the activity of a specific protein towards a defined surface. Indications are that protein-protein associations may affect antibody detectability, but in some cases this is the result of altered antigenic accessibility rather than physical removal of the molecule. The antibody binding patterns are also quite variable over an entire methyl-silanol wettability gradient on silicon, suggesting that the surface itself is affecting protein-protein and protein-protein-surface associations. Ellipsometric studies were carried out on the gradients which were incubated in single; binary and tertiary physiological concentration solutions of human albumin, immunoglobulin G (IgG) and fibrinogen. The ellipsometric-antibody detectability of the proteins on such surfaces were found to be variable, depending upon the location on the gradient and the order and combination in which the proteins were presented to the surface. Radiolabelled proteins were studied on discrete regions of these gradients. Competitive effects of albumin were found to be inhibitory (negative) with respect to IgG adsorption on hydrophobic surfaces, while enhancing IgG deposition on hydrophilic surfaces (positive). Scanning force microscopy in the so-called tapping mode indicates that proteins, particularly IgG, organize themselves differently with respect to surfaces, depending upon the nature of the surface and the presence of other proteins.

Animals↗
PubMed1993

An in-vitro study of H 2O 2-treated titanium surfaces in contact with blood plasma and a simulated body fluid.

Ellipsometry and antibody techniques were used to investigate plasma protein adsorption onto titanium (Ti) surfaces pretreated in hydrogen peroxide (H 2O 2). Surfaces preincubated for short times in 10 mM or 100 mM H 2O 2 bound relatively large amounts of anti-high molecular weight kininogen (a-HMWK) after immersion in blood plasma. Increasing the preincubation time in H 2O 2 led to an increase in the total amount of bound plasma proteins and a large deposition of anti-fibrinogen (a-Fib). Large amounts of a-HMWK and a-Fib were also deposited onto surfaces washed in trichloroethane, acetone and ethanol, whereas radiofrequency plasma-treated surfaces or surfaces incubated in deionized water bound preferentially a-HMWK after plasma immersion. Auger electron spectroscopy (AES) made on Ti-surfaces preincubated in 10 mM and 100 mM H 2O 2 solutions showed an increased oxide thickness and, after 16 h of immersion in a physiological buffer, an increased amount of calcium on and throughout the oxide. The rate of net oxide growth was larger in 10 mM than in 100 mM H 2O 2.

Blood Proteins↗
PubMed1992

Antisera binding onto metals immersed in human plasma in vitro.

Titanium (Ti), silicon (Si), silver (Ag), vanadium (V), gold (Au), and chromium (Cr) surfaces were made hydrophilic by radiofrequency plasma treatment. The binding of antifibrinogen (a-fib) and anti-high-molecular-weight kininogen (a-HMWK) after incubation of surfaces in 10% human blood plasma was investigated with ellipsometry. Ti and Si surfaces bound a-HMWK but no detectable amounts of a-fib, whereas the other metals bound both types of antisera. Protein adsorption in a fluid gradient produced under a convex lens indicated that the small deposition of a-fib on Ti and Si surfaces is probably a result of protein displacement. This displacement was not evident at lens positions simulating low plasma concentrations where large amounts of a-fib adsorbed. Surfaces washed sequentially in trichloroethane, acetone, and ethanol produced more hydrophobic surfaces and resulted in slower rates of a-fib displacement. These studies would indicate that some metals form complexes with specific plasma proteins or, alternatively, that different metals may bind equal amounts of plasma proteins which express differing antigenicities toward their surroundings.

Adsorption↗
PubMed1992

Studies of surface activated coagulation: antisera binding onto methyl gradients on silicon incubated in human plasma in vitro.

Human plasma proteins factor XII, high molecular weight kininogen, prekallikrein, factor XI and fibrinogen, participate in surface-initiated coagulation. Antisera binding to methyl gradients made on hydrophilic silicon was studied after immersion in normal and deficient human blood plasma. Scanning ellipsometry was used to quantify the adsorbed organic material. The hydrophilic part of the gradient deposited anti-factor XII and anti-high molecular weight kininogen, but low amounts of anti-fibrinogen. Increased amounts of anti-fibrinogen bound onto the hydrophobic part, and the intermediate gradient region with mixed polar-nonpolar surface characteristics bound low amounts of anti-factor XII, anti-high molecular weight kininogen and anti-fibrinogen. Tentatively, in this gradient region, simultaneous polar and non-polar surface characteristics result in a low-level of surface-activated coagulation. Surfaces immersed in heparinized-and EDTA-plasma indicate different antisera depositions.

Adsorption↗
PubMed1992

Physico-chemical considerations of titanium as a biomaterial.

Physico-chemical properties of titanium are discussed. Special attention is paid to those of amorphous TiO 2 that contact tissues in vivo. In aqueous environments TiO 2. (aq) has low ion-formation tendency and low reactivity with macromolecules. This is accompanied by low toxicity. Titanium does not facilitate reactive oxygen radical generation during inflammatory conditions as observed in in-vitro experiments. The outermost layers of the oxide are in the Ti(IV) oxidation state, although using electron spin resonance (ESR) techniques, formation of Ti(III) is observed at atmospheric conditions. The impact of similarities between water and TiO 2 is speculated upon, and the physico-chemical properties of titanium are tentatively linked to some in-vivo consequences.

Biocompatible Materials↗
PubMed1992

Measurements of light transmission through single melanophores.

A photometrical method has been developed that allows assessment of subcellular pigment migration in melanophores of the fish cockoo wrasse (Labrus ossifagus L.) The pigment migration was studied with local light spot transmission measurements. Depending on where the light beam is placed on the melanophores it is possible to study events within an area of approximately 75 microns 2. Measuring pigment translocation in different parts of a melanophore gives new possibilities to study how cell membrane receptor-mediated signals are spread within a single cell, which will increase our understanding of how receptor activating drugs exert their cellular effect. The technique can be used in pharmacological and biophysical studies and in biosensors, pharmaceutical screens, environmental detectors, etc. The method clearly has the ability to study local and small changes in light transmission due to displacement of melanophore pigment granules. Since one melanophore on the tip of an optical fibre would be enough to obtain a measurable effect, the presented technique provides the basis for future development of biosensors small enough for in vivo applications, e.g., to monitor the catecholamine levels of circulating blood.

Animals↗
PubMed1991

The melanophore aggregating response of isolated fish scales: a very rapid and sensitive diagnosis of whooping cough.

Pertussis toxin (PT) has been found to block noradrenaline-induced pigment aggregation in fish melanophores, and, based on this, a rapid and highly sensitive assay for PT was developed. Some preliminary results have also indicated that it may be possible to detect PT-like activity in saliva samples from patients with clinically suspected pertussis. In the present study the diagnostic value of the fish melanophore method was evaluated in 70 patients suspected of having pertussis; culture, serology and physician diagnosis were used as reference methods. In 60 of the patients, pertussis was verified by at least one of the reference methods. The melanophore test showed PT-like activity in saliva samples from 58 of the patients. Three patients with reference-verified pertussis showed no PT-like activity in the test; among these, one patient had been immunized and had also been treated with erythromycin during 3 days immediately prior to visiting the hospital. The melanophore test has three major advantages: it allows detection of pertussis in the early and curable stage of the disease; it takes only 2 h to perform; and it requires no sophisticated equipment.

Adolescent↗
PubMed1991

Structure of adsorbed fibrinogen obtained by scanning force microscopy.

It is shown that scanning force microscopy (SFM), operated in the attractive mode, can be used to obtain high resolution pictures of adsorbed fibrinogen molecules on solid surfaces, without the need for staining or special microscope grids. SFM also reveals the three-dimensional structure of the adsorbed molecules. Two forms of adsorbed fibrinogen are demonstrated on hydrophobic silicone dioxide surfaces: a trinodular about 60 nm long and a globular with about a 40 nm diameter. Polymeric networks formed after storage of the surface with adsorbed fibrinogen in PBS for 11 days are also shown. The SFM-results for the trinodular structure suggest the existence of loops or peptide chains extending outside the basic structure of the fibrinogen molecule.

Fibrinogen↗
PubMed1991

'Lens-on-surface': a versatile method for the investigation of plasma protein exchange reactions on solid surfaces.

The exchange sequence of plasma proteins in narrow spaces on solid surfaces was studied by means of a modified 'lens-on-surface' method as originally described by Vroman and Adams. In our studies, lateral scanning ellipsometry was used as the detection method. With the use of antibodies it was demonstrated and confirmed that immunologically detectable plasma protein antigens appear and disappear in a time- and concentration-dependent sequence [IgG followed by fibrinogen followed by high-molecular weight kininogen (HMWK)] on silica surfaces. Plasma protein exchange reactions were also studied on hydrophilic titanium (Ti), vanadium (V), and silver (Ag) surfaces. Atypical exchange patterns were found on V and Ag surfaces as compared with hydrophilic silica (adsorbed fibrinogen was not removed).

Adsorption↗