Macrophage migration inhibitory factor may play a protective role in osteoarthritis

Background Osteoarthritis (OA) is the most prevalent form of arthritis and the major cause of disability and overall diminution of quality of life in the elderly population. Currently there is no cure for OA, partly due to the large gaps in our understanding of its underlying molecular and cellular mechanisms. Macrophage migration inhibitory factor (MIF) is a procytokine that mediates pleiotropic inflammatory effects in inflammatory diseases such as rheumatoid arthritis (RA) and ankylosing spondylitis (AS). However, data on the role of MIF in OA is limited with conflicting results. We undertook this study to investigate the role of MIF in OA by examining MIF genotype, mRNA expression, and protein levels in the Newfoundland Osteoarthritis Study. Methods One hundred nineteen end-stage knee/hip OA patients, 16 RA patients, and 113 healthy controls were included in the study. Two polymorphisms in the MIF gene, rs755622, and -794 CATT5-8, were genotyped using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) and PCR followed by automated capillary electrophoresis, respectively. MIF mRNA levels in articular cartilage and subchondral bone were measured by quantitative polymerase chain reaction. Plasma concentrations of MIF, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) were measured by enzyme-linked immunosorbent assay. Results rs755622 and -794 CATT5-8 genotypes were not associated with MIF mRNA or protein levels or OA (all p ≥ 0.19). MIF mRNA level in cartilage was lower in OA patients than in controls (p = 0.028) and RA patients (p = 0.004), while the levels in bone were comparable between OA patients and controls (p = 0.165). MIF protein level in plasma was lower in OA patients than in controls (p = 3.01 × 10−10), while the levels of TNF-α, IL-6 and IL-1β in plasma were all significantly higher in OA patients than in controls (all p ≤ 0.0007). Multivariable logistic regression showed lower MIF and higher IL-1β protein levels in plasma were independently associated with OA (OR per SD increase = 0.10 and 8.08; 95% CI = 0.04–0.19 and 4.42–16.82, respectively), but TNF-α and IL-6 became non-significant. Conclusions Reduced MIF mRNA and protein expression in OA patients suggested MIF might have a protective role in OA and could serve as a biomarker to differentiate OA from other joint disorders

Influence of CO2-wettability on CO2 migration and trapping capacity in deep saline aquifers

CO2 migration and trapping capacity in deep saline aquifers are highly influenced by various rock and fluid parameters. One of the key parameters, which has received little attention, is CO2-wettability. We thus simulated the behavior of a CO2 plume in a deep saline aquifer as a function of rock wettability and predicted various associated CO2 migration patterns and trapping capacities. We clearly show that CO2-wet reservoirs are most permeable for CO2; CO2 migrates furthest upwards and the plume has a candle-like shape, while in a water-wet reservoir the plume is more compact and rain-drop shaped. Furthermore, higher residual trapping capacities are achieved in water-wet rock, while solubility trapping is more efficient in CO2-wet rock. We thus conclude that rock wettability has a highly significant impact on both CO2 migration and trapping capacities and that water-wet reservoirs are preferable CO2 sinks due to their higher storage capacities and higher containment security

Insulin resistance and cardiac metabolism

Insulin resistance, clinically defined as a defect of insulin action, is closely linked to an increased incidence of cardiovascular disease. Although metabolic abnormalities have been known to initiate heart failure, the relationship between insulin resistance and cardiac metabolism is currently unclear. In my initial study, acute effects of dexamethasone (DEX) on rat cardiac metabolism were examined. A single dose of DEX leads to whole-body insulin resistance. Moreover, in hearts from these animals, glucose oxidation is compromised due to augmentation of pyruvate dehydrogenase kinase (PDK4), whereas amplification of LPL increases lipoprotein triglyceride clearance, likely providing the heart with excessive FA that are then stored as intracellular triglyceride. In the heart, AMP-activated protein kinase (AMPK) is an important regulator of both lipid and carbohydrate metabolism. Once stimulated, AMPK inhibits acetyl-CoA carboxylase (ACC), which catalyzes the conversion of acetyl-CoA to malonyl-CoA. This decreases malonyl-CoA, minimizes its inhibition of FA oxidation, and FA utilization increases. Cardiac palmitate oxidation in DEX treated hearts was higher compared to control, and was coupled to increased phosphorylation of ACC₂₈₀. Measurement of polyunsaturated FAs demonstrated a drop in linoleic and gamma linolenic acid, with an increase in arachidonic acid after acute DEX injection. Given the detrimental effects of compromised glucose utilization, high FA oxidation, TG storage, and arachidonic acid accumulation, our data suggests that these effects of DEX on cardiac metabolism could explain the increased cardiovascular risk associated with chronic glucocorticoid therapy. Although a small portion of the patient population exhibits glucocorticoid-induced insulin resistance, the primary cause of this syndrome is excessive circulating FA, usually associated with obesity. The concluding study in my Ph.D. project was to explore the effects of acute high FA induced insulin resistance on LPL at the coronary lumen. Acute IL infusion augments plasma LPL, and this was associated with reduced LPL activity at the coronary lumen, but increased enzyme within endothelial cells and subendothelial space. It is likely that these effects are a consequence of FA releasing LPL from apical endothelial HSPG, in addition to augmenting endothelial heparanase, which facilitates myocyte HSPG cleavage and transfer of LPL towards the coronary lumen. These data suggest that the control of cardiac LPL is complex, and insulin resistance, in the presence or absence of high FA have differential effect on the enzyme.Pharmaceutical Sciences, Faculty ofGraduat

Myosin light chain phosphorylation facilitates in vivo myosin filament reassembly after mechanical perturbation

It is generally believed that the myosin thick filaments in smooth muscle are structurally less stable than those in striated muscle. In vitro studies have shown that phosphorylation of the 20-kD myosin light chain (MLC) facilitates formation of the thick filaments from monomeric myosins in solution. It appears that the structural integrity of the thick filaments can be enhanced by phosphorylation of the MLC. It is however not known whether the transition from monomeric to filamentous myosin occurs in intact smooth muscle when the light chains are phosphorylated during muscle activation. The physiological significance of the thick filament lability and the role of MLC phosphorylation in modulating the filament integrity in intact smooth muscle are still being debated. It has been shown in our laboratory that mechanical strain is able to induce partial dissolution of unphosphorylated myosin thick filaments in intact smooth muscle; repolymerization of the thick filaments occurs when the muscle is subjected to cycles of contraction and relaxation. The objective of my thesis research is to determine whether MLC phosphorylation is required for repolymerization of the thick filaments after they have been partially disassembled by mechanical agitation. We used the conventional electron microscopy to quantify the cross-sectional density of myosin thick filaments in airway smooth muscle; partial dissolution of the thick filaments was induced by applying length oscillations to the muscle preparation; recovery of the thick filament density after oscillation was examined in the presence and absence of wortmannin, a potent inhibitor of myosin light chain kinase (MLCK). The results showed that isometric force production in airway smooth muscle was totally dependent on MLC phosphorylation. The inhibition of MLC phosphorylation alone did not cause disassembly of myosin filaments. The unphosphorylated thick filaments however partially dissolved when the muscle was subjected to oscillatory strains, as evidenced by a 25% decrease in the filament density. The post-oscillation filament density did not recover when wortmannin was present; it recovered to the pre-oscillation level when wortmannin was removed. Based on the above findings, we conclude that thick filament formation in vivo is MLC phosphorylation dependent.Medicine, Faculty ofAnesthesiology, Pharmacology and Therapeutics, Department ofGraduat

Effects of Cyclosporine on Reperfusion Injury in Patients: A Meta-Analysis of Randomized Controlled Trials

Mitochondrial permeability transition pore (mPTP) opening due to its role in regulating ROS generation contributes to cardiac reperfusion injury. In animals, cyclosporine (cyclosporine A, CsA), an inhibitor of mPTP, has been found to prevent reperfusion injury following acute myocardial infarction. However, the effects of CsA in reperfusion injury in clinical patients are not elucidated. We performed a meta-analysis using published clinical studies and electronic databases. Relevant data were extracted using standardized algorithms and additional data were obtained directly from investigators as indicated. Five randomized controlled blind trials were included in our meta-analysis. The clinical outcomes including infarct size (SMD: −0.41; 95% CI: −0.81, 0.01; P = 0.058), left ventricular ejection fraction (LVEF) (SMD: 0.20; 95% CI: −0.02, 0.42; P = 0.079), troponin I (TnI) (SMD: −0.21; 95% CI: −0.49, 0.07; P = 0.149), creatine kinase (CK) (SMD: −0.32; 95% CI: −0.98, 0.35; P = 0.352), and creatine kinase-MB isoenzyme (CK-MB) (SMD: −0.06; 95% CI: −0.35, 0.23; P = 0.689) suggested that there is no significant difference on cardiac function and injury with or without CsA treatment. Our results indicated that, unlike the positive effects of CsA in animal models, CsA administration may not protect heart from reperfusion injury in clinical patients with myocardial infarction

The Shift of ERG B-Wave Induced by Hours' Dark Exposure in Rodents

<div><p>Purpose</p><p>Dark adaptation can induce a rapid functional shift in the retina, and after that, the retinal function is believed to remain stable during the continuous dark exposure. However, we found that electroretinograms (ERG) b-waves gradually shifted during 24 hours’ dark exposure in rodents. Detailed experiments were designed to explore this non-classical dark adaptation.</p><p>Methods</p><p>In vivo ERG recording in adult and developing rodents after light manipulations.</p><p>Results</p><p>We revealed a five-fold decrease in ERG b-waves in adult rats that were dark exposed for 24 hours. The ERG b-waves significantly increased within the first hour’s dark exposure, but after that decreased continuously and finally attained steady state after 1 day’s dark exposure. After 3 repetitive, 10 minutes’ light exposure, the dark exposed rats fully recovered. This recovery effect was eye-specific, and light exposure to one eye could not restore the ERGs in the non-exposed eye. The prolonged dark exposure-induced functional shift was also reflected in the down-regulation on the amplitude of intensity-ERG response curve, but the dynamic range of the responsive light intensity remained largely stable. Furthermore, the ERG b-wave shifts occurred in and beyond classical critical period, and in both rats and mice. Importantly, when ERG b-wave greatly shifted, the amplitude of ERG a-wave did not change significantly after the prolonged dark exposure.</p><p>Conclusions</p><p>This rapid age-independent ERG change demonstrates a generally existing functional shift in the retina, which is at the entry level of visual system.</p></div

ERG amplitude and peak latency gradually decreased after the continuous dark exposure.

<p>(A) ERGs evoked by a 50 ms flash (-1.14log cd*s/m²) recorded during continuous dark exposure for 7 hours. Time 0 was set as 30 minutes after the onset of dark exposure. Gray lines are the peak latency at time 0. The solid blue lines are mean responses (n = 8), and the gray shadows represent SEM. (B) The statistics of the b-wave amplitudes at each recording time (n = 8, error bars, ± SEM). (C) The b-wave peak latencies recorded at different time points during continuous dark exposure. (D) The mean b-wave amplitudes of ERG response to a 50 ms flash (-1.14log cd*s/m²) of rats dark exposed for 0, 12, 24 and 48 hours (n = 8 for each group). The mean values of each group are illustrated by black squares (* p<0.05, *** p<0.001, t test). (E) The b-wave peak latency recordings at the identical time points in D. (* p<0.05, *** p<0.001. t test). (F)The b-wave amplitudes of the dark exposed rats (n = 10) to a 50 ms flash (-1.14log cd*s/m²) at day (6:00–18:00) and night (18:00–6:00) time period. (G)The ERG b-wave peak latencies in the above-mentioned two groups. The short vertical solid bars denote SEM in B-G.</p

Prolonged dark exposure induced shift in ERG response and its restoration by subsequent light exposure.

<p>(A) ERG amplitude and peak latency measurements. (B) The preparation prior to ERG recording of three groups of rats. (C) A comparison of b-wave responses to a -1.14 log cd*s/m2 flash between normally reared (blue, n = 8) and dark prolonged rats (red, n = 8) showed a significant b-wave suppression. The mean response is represented by the solid line, and SEM is shown as the shadow. Dotted line shows the peak latency in normally reared rats. (D) A comparison of b-wave responses response to a 50 ms flash (-1.14log cd*s/m²) between normally reared rats (blue, n = 8) and prolonged dark exposed plus 3 repetitive, brief (10 minutes) light exposed rats (green, n = 8). Symbols are identical to those in C. (E) The b-wave amplitudes of the three groups (normally reared rats, n = 8; Prolonged DE rats, n = 8; Prolonged DE+3 LE rats, n = 8). (F) The statistics of the b-wave peak latencies of the three groups, samples, and symbols are identical to those in E (*** p<0.001, t test, error bars, ±SEM).</p

ERG shifts in and beyond the classical critical period and in both rats and mice.

<p>(A) ERG b-waves response to a 50 ms flash (-1.14log cd*s/m²) recorded from one animal in each group before and after 10 minutes light exposure. (B) Restoration effects in ERG b-wave amplitudes from the three groups before and after 10 minutes of light exposure (* p<0.05, all paired t test). Short vertical solid bars denote SEM.</p