Exhaled breath condensate pH standardised for CO2 partial pressure.

Exhaled breath condensate (EBC) pH is considered to reflect the acid-base balance of the airways. Current pH measurements do not take into account the effect of CO2. The aim of the present study was to determine the effect of condensate CO2 partial pressure on pH and to provide a more precise mode of EBC pH determination. Condensate pH and CO2 partial pressure were measured in parallel from 12 healthy volunteers and 12 asthmatics using a blood gas analyser in neat, argon de-aerated and CO2-loaded samples. The regression analysis was used to test the relationship between pH and CO2, and to calculate the pH at a CO2 level of 5.33 kPa (physiological alveolar CO2 partial pressure). Reproducibility of different pH readings was compared using the Bland-Altman test. Condensate CO2 concentration was variable both in neat and argon de-aerated samples. There was a close negative logarithmic relationship between CO2 and pH. Calculation of pH at a CO2 level of 5.33 kPa provided reproducibility approximately six times as good as that of the currently used measurements. Condensate CO2 partial pressure influences pH measurements. Determination of pH at a standard CO2 level provides the most reproducible condensate pH values to date.

Bone resorption activity of particulate-stimulated macrophages.

Particulate wear debris from bone cement or prosthetic components can stimulate macrophages to cause bone resorption in a dose-dependent manner. This bone resorption activity of particulate-stimulated macrophages is associated with increased levels of both prostaglandin E2 (PGE2) and interleukin-1 (IL-1). In this study we compared the effect of particulate size, concentration, and composition on the secretion of IL-1 and PGE2 by peritoneal macrophages and on the bone-resorbing activity of conditioned medium (CM) harvested from particulate-challenged macrophages. Particulates (titanium, Ti; polymethylmethacrylate, PMMA; and polystyrene, PS) only with phagocytosable size stimulated peritoneal macrophages to secrete IL-1 and PGE2 in a dose- and time-dependent manner. Ti particles (1-3 microns) exhibited significantly enhanced bone-resorbing activity measured as 45Ca release. The maximum bone-resorbing response was observed at a concentration of 0.1% Ti (approximately 10-15 Ti particulates per cell), which also corresponded with the highest IL-1 levels measured in particulate-challenged CM. This was measured using either conditioned media from Ti-stimulated macrophages or in cocultures of calvarial bone and macrophages in the presence of Ti. Exogenous PGE2 and recombinant human IL-1 could significantly increase the 45Ca release; indomethacin (IM) significantly reduced both the spontaneous calcium efflux and active 45Ca release from in vivo labeled calvarial bones. However, IM and/or anti-IL-1 antibodies could suppress only partly the macrophage-mediated bone resorption, indicating that, in a macrophage-bone coculture system, factors other than PGE2 and IL-1 also may regulate particulate-induced bone resorption, probably involving multiple cell types.

Expression of alternatively spliced epidermal growth factor-like domains in aggrecans of different species. Evidence for a novel module.

The carboxyl-terminal globular domain of human aggrecan has been shown previously to contain an alternatively spliced epidermal growth factor (EGF)-like module. We have used reverse transcription/polymerase chain reactions on cartilage-derived RNAs to investigate the heterogeneity in the EGF-like domain content of aggrecans from five species (mouse, rat, dog, bovine, and human). A novel alternatively spliced EGF-like module was detected in human aggrecan, establishing the presence of two of these domains. Highly homologous domains are present in aggrecans of other species, and the expression of these modules is identical (4-8%). They share significant homology with EGF-like domains of differentiation proteins and coagulation factors and have a putative calcium binding site. In contrast to this novel domain (EGF2), the previously described EGF-like module (EGF1) is expressed at a high level exclusively in human aggrecan. The expression of the two EGF-like domains in human aggrecan appears to be independent. Although the function of these domains is not understood, the uniform expression of the EGF2 domain may indicate a general role of this aggrecan module, while the expression of the EGF1 domain may reflect species specificity.

The diagnostic significance of autoantibodies against cartilage components or their counterparts in destructive articular diseases.

In this work four different types of antibodies to collagens, membrane protein of chondrocytes (MP), cartilage matrix proteins (CMP) and heat shock proteins (HSP-s) were tested in order to find an available clinical laboratory method for diagnostic and monitoring purposes in patients suffering from osteoarthritis. From the point of view of diagnostic efficiency, the estimation of antibody level to MP seemed to be the best and as a supplementary method the determination of rheuma factor was recommended. The anticollagen antibody estimation is less sensitive, anti CMP antibodies are not detectable. In spite of immunological crossreaction between HSP and cartilage matrix component the antibody level against HSP has no correlation with osteoarthritis. The appearance of humoral reaction, antibodies against different cartilage specific collagens and chondrocyte membrane proteins, is an epiphenomenon, however as the supposed immune complexes, trapped in a cartilage, play an important role in the damage of cartilage which may explain the self-perpetuating and chronic nature of cartilage degradation on osteoarthritis.

The clinical diagnostic significance of the investigation of receptor mediated pathway of LDL.

Some types of LDL-receptor investigations have been demonstrated which can also be carried out in routine clinical laboratory. Special attention has been layed on the testing of lymphocytes and monocytes which are available easier than tissue samples but, which are, however, according to our experiences appropriate for the LDL receptor analysis.