Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture-damaged and reference schools: results of HITEA study.

Aiming to identify factors causing the adverse health effects associated with moisture-damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture-damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture-damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor-α (TNF-)α, interleukin (IL)-6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3-hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture-damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL-6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram-positive bacteria.

Site-dependent changes in structure and function of lapine articular cartilage 4 weeks after anterior cruciate ligament transection.

OBJECTIVE: The aim of this study was to investigate the site-dependent changes in the structure and function of articular cartilage in the lapine knee joint at a very early stage of osteoarthritis (OA), created experimentally by anterior cruciate ligament transection (ACLT). METHODS: Unilateral ACLT was performed in eight mature New Zealand white rabbits. ACL transected and contralateral (C-L) joints were prepared for analysis at 4 weeks after ACLT. Three rabbits with intact joints were used as a control group (CNTRL). Femoral groove, medial and lateral femoral condyles, and tibial plateaus were harvested and used in the analysis. Biomechanical tests, microscopy and spectroscopy were used to determine the biomechanical properties, composition and structure of the samples. A linear mixed model was chosen for statistical comparisons between the groups. RESULTS: As a result of ACLT, the equilibrium and dynamic moduli were decreased primarily in the femoral condyle cartilage. Up to three times lower moduli (P < 0.05) were observed in the ACLT group compared to the control group. Significant (P < 0.05) proteoglycan (PG) loss in the ACLT joint cartilage was observed up to a depth of 20-30% from the cartilage surface in femoral condyles, while significant PG loss was confined to more superficial regions in tibial plateaus and femoral groove. The collagen orientation angle was increased (P < 0.05) up to a cartilage depth of 60% by ACLT in the lateral femoral condyle, while smaller effects, but still significant, were observed at other locations. The collagen content was increased (P < 0.05) in the middle and deep zones of the ACLT group compared to the control group samples, especially in the lateral femoral condyle. CONCLUSION: Femoral condyle cartilage experienced the greatest structural and mechanical alterations in very early OA, as produced by ACLT. Degenerative alterations were observed especially in the superficial collagen fiber organization and PG content, while the collagen content was increased in the deep tissue of femoral condyle cartilage. The current findings provide novel information of the early stages of OA in different locations of the knee joint.

Comparison of elastic, viscoelastic and failure tensile material properties of knee ligaments and patellar tendon.

The knee ligaments and patellar tendon function in concert with each other and other joint tissues, and are adapted to their specific physiological function via geometry and material properties. However, it is not well known how the viscoelastic and quasi-static material properties compare between the ligaments. The purpose of this study was to characterize and compare these material properties between the knee ligaments and patellar tendon. Dumbbell-shaped tensile test samples were cut from bovine knee ligaments (ACL, LCL, MCL, PCL) and patellar tendon (PT) and subjected to tensile testing (n = 10 per ligament type). A sinusoidal loading test was performed at 8% strain with 0.5% strain amplitude using 0.1, 0.5 and 1 Hz frequencies. Subsequently, an ultimate tensile test was performed to investigate the stress-strain characteristics. At 0.1 Hz, the phase difference between stress and strain was higher in LCL compared with ACL, PCL and PT (p < 0.05), and at 0.5 Hz that was higher in LCL compared with all other ligaments and PT (p < 0.05). PT had the longest toe-region strain (p < 0.05 compared with PCL and MCL) and MCL had the highest linear and strain-dependent modulus, and toughness (p < 0.05 compared with ACL, LCL and PT). The results indicate that LCL is more viscous than other ligaments at low-frequency loads. MCL was the stiffest and toughest, and its modulus increased most steeply at the toe-region, possibly implying a greater amount of collagen. This study improves the knowledge about elastic, viscoelastic and failure properties of the knee ligaments and PT.

Forearm tremor in relation to selected physiological and body dimensional variables.

Interrelationships between forearm tremor and a number of body dimensional, muscle structure, muscular strength and training background variables were studied among 13 male students with athletic backgrounds. The subjects performed isometric dominant upper extremity elbow flexions with a 90 degrees joint angle and with the forearm held in a horizontal position. A freely hanging mass was attached via a strain gauge transducer, a metal chain and cuff to the forearm. An accelerometer attached to the cuff measured the vertical component of tremor. The power spectrum density function was calculated for a tremor acceleration signal and a bandwidth of 7-20 Hz was analysed in more detail. The right M. vastus lateralis was biopsed in order to determine the muscle fiber composition. Arm mass and muscle fiber composition were found to correlate statistically significantly with the tremor frequency characteristics. In the further analyses arm mass was found to be the only variable explaining the tremor frequency characteristics; the effects of the muscle structure variables were minor when the effects of arm mass was controlled in partial correlation analyses. Interindividual differences in motor unit firing properties were presumed to explain the dependence found between arm mass and tremor frequency.

Time- and dose-dependent DNA binding of PAHs derived from diesel particle extracts, benzo[a]pyrene and 5-methychrysene in a human mammary carcinoma cell line (MCF-7).

Cultures of a human mammary carcinoma cell line (MCF-7) were exposed to the soluble organic fraction of diesel particle emissions, benzo[a]pyrene (B[a]P) and 5-methylchrysene (5-MeCHR) to study time- and dose-related PAH-DNA binding. The concentrations of 14 PAHs in three extracts were analyzed by HPLC and PAH-DNA adducts were measured by (32)P post-labeling assay. Time-dependent DNA adducts formation of 2.5 microM B[a]P was lower than that of 2.5 microM 5-MeCHR. In comparison with B[a]P, 2-fold higher adduct formation by 5-MeCHR was observed at 12 h exposure, after which BPDE adducts decreased and 5-MeCHR continued to form adducts linearly during 48 h exposure. The data for these two PAH compounds demonstrate a large variation in adduct-forming potency, which should be taken into account when estimating DNA adducts formed by mixtures of unknown PAHs. A clear dose-response effect on formation of DNA adducts was obtained for B[a]P and a Standard Reference Material (SRM) of diesel particulate matter. The amount of B[a]P contributed more to total DNA adduct formation by SRM than by three diesel extracts. Thus, no conclusions can be drawn from diesel particle-derived B[a]P as to the adduct-forming potency of other carcinogenic PAHs. There was little change in adduct levels formed by three diesel extracts from 0 to 12 h exposure. Thereafter, the number of adducts formed by RD2 increased more rapidly than those formed by RD1 and EN97. The concentrations of 14 PAHs and adduct levels analyzed at 24 and 48 h did not change in the same proportion between the extracts. Neither could PAH-DNA adduct levels be explained by the sum of strong and weak adduct-forming PAHs analyzed in the extracts. This indicates that other PAHs in the extracts RD1, RD2 and EN97 contributed to adduct formation more than the carcinogenic adduct-forming PAHs analyzed in this study.