Pre- and post-bronchodilator lung function as predictors of mortality in the Lung Health Study

Background

Chronic obstructive pulmonary disease (COPD) is supposed to be classified on the basis of post-bronchodilator lung function. Most longitudinal studies of COPD, though, do not have post-bronchodilator lung function available. We used pre-and post bronchodilator lung function data from the Lung Health Study to determine whether these measures differ in their ability to predict mortality.

Methods

We limited our analysis to subjects who were of black or white race, on whom we had complete data, and who participated at either the 1 year or the 5 year follow-up visit. We classified subjects based on their baseline lung function, according to COPD Classification criteria using both pre- and post-bronchodilator lung function. We conducted a survival analysis and logistic regression predicting death and controlling for age, sex, race, treatment group, smoking status, and measures of lung function (either pre- or post-bronchodilator. We calculated hazard ratios (HR) with 95% confidence intervals (CI) and also calculated area under the curve for the logistic regression models.

Results

By year 15 of the study, 721 of the original 5,887 study subjects had died. In the year 1 sample survival models, a higher FEV₁ % predicted lower mortality in both the pre-bronchodilator (HR 0.87, 95% CI 0.81, 0.94 per 10% increase) and post-bronchodilator (HR 0.84, 95% CI 0.77, 0.90) models. The area under the curve for the respective models was 69.2% and 69.4%. Similarly, using categories, when compared to people with "normal" lung function, subjects with Stage 3 or 4 disease had similar mortality in both the pre- (HR 1.51, 95% CI 0.75, 3.03) and post-bronchodilator (HR 1.45, 95% CI 0.41, 5.15) models. In the year 5 sample, when a larger proportion of subjects had Stage 3 or 4 disease (6.4% in the pre-bronchodilator group), mortality was significantly increased in both the pre- (HR 2.68, 95% CI 1.51, 4.75) and post-bronchodilator (HR 2.46, 95% CI 1.63, 3.73) models.

Conclusions

Both pre- and post-bronchodilator lung function predicted mortality in this analysis with a similar degree of accuracy. Post-bronchodilator lung function may not be needed in population studies that predict long-term outcomes.     

The impact of the Mid-Pleistocene Transition on the composition of submerged reefs of the Maui Nui Complex,Hawaii

The submarine reef terraces (L1–L12) of the Maui Nui Complex (MNC—the islands of Lanai, Molokai, Maui and Kahoolawe) in Hawaii provide a unique opportunity to investigate the impact of climate and sea level change on coral reef growth by examining changes in reef development through the Mid-Pleistocene Transition (900–800 ka). We present an analysis of the biological and sedimentary composition of the reefs that builds directly on recently published chronological and morphological data. We define nine distinct limestone facies and place them in a spatial and stratigraphic context within 12 reef terraces using ROV and submersible observations. These include oolitic, two coral reef, two coralline algal nodule, algal crust, hemi-pelagic mud, bioclastic and peloidal mud facies. These facies characterise environments from high energy shallow water coral reef crests to low energy non-reefal deep-water settings. Combining the bottom observations and sedimentary facies data, we report a shift in the observed sedimentary facies across the submerged reefs of the MNC from dominant shallow coral reef facies on the deep reefs to coralline algae dominated exposed outcrop morphology on the shallower reefs. We argue that this shift is a reflection of the change in period and amplitude of glacioeustatic sea level cycles (41 kyr and 60–70 m to 100 kyr and 120 m) during the Mid-Pleistocene Transition (MPT, ~ 800 ka), coupled with a slowing in the subsidence rate of the complex. The growth of stratigraphically thick coral reef units on the deep Pre-MPT reefs was due to the rapid subsidence of the substrate and the shorter, smaller amplitude sea level cycles allowing re-occupation and coral growth on successive cycle low-stands. Longer, larger amplitude sea level cycles after the MPT combined with greater vertical stability at this time produced conditions conducive to deep-water coralline algae growth which veneered the shallower terraces. Additionally, we compare reef development both within the MNC, and between the MNC and Hawaii. Finally we suggest that climatic forcings such as sea-surface temperature and oceanographic currents may also have influenced the distribution of coral species within the sample suite, e.g., the disappearance of the Acropora genus from the Maui Nui Complex in the Middle Pleistocene.     

Comparative study of the active site caging of serine proteases: thrombin and factor Xa

Bovine thrombin and human factor Xa were acylated at their active site selectively with inhibitors derived from the parent compound 4-guanidinophenyl (E)-4-diethylamino-2-hydroxy-alpha-methylcinnamate hydrochloride, 1b. Peptidyl side chains were attached to the phenol ring via amide connection, which served as a recognition motif in inhibiting different serine proteases. Upon irradiation with 366 nm light, the trans-cinnamate attached to the active-site serine isomerizes to the cis isomer which then rapidly lactonizes to release the free enzyme. The peptidyl side chain sequences specific for each serine protease were revealed via constructing and screening a library of homologous compounds. This methodology may be applied to other proteases. One application based on enzyme-specific, photoactivatable inhibitors is to isolate a designated active protease from a mixture of several proteases. Thus, a cinnamate inhibitor with a biotin moiety, 1d, was synthesized. A solution of enzyme-specific, biotinylated inhibitor was added into a mixture of proteases containing a target enzyme. The target enzyme was acylated at the active site and subsequently bore a biotin tail. An avidin column was used to separate the biotinylated enzyme from the unmodified ones, by a strong binding between biotin and avidin. After a brief irradiation on the avidin column, the retained enzymes were released from the biotin tag and eluted off the column. To demonstrate the idea, thrombin and factor Xa have been separated from each other by this strategy.     

Ecological characteristics of Brachychiton populneus (Sterculiaceae) (kurrajong) in relation to the invasion of urban bushland in south‐western Australia

Brachychiton populneus (Sterculiaceae) (Schott et Endl.) R. Br. (kurrajong) is a small tree that occurs naturally ranging from southern Queensland to Victoria. It has been widely planted as an ornamental tree in south‐western Australia. In Kings Park, B. populneus has moved from cultivation to become a weed in the adjoining bushland reserve. The aim of this study was to examine the ecology of B. populneus and the Kings Park environment in order to identify the particular conjunction of characteristics that have led to the species becoming a weed. The highest density of kurrajongs (69.3 trees ha^–1) was observed in the most disturbed area of Kings Park, and there was a strong relationship between density of B. populneus and disturbance (P = 0.058). The most striking feature of the invasion was the tendency of B. populneus to occur beneath other tree species, and this was attributed to birds feeding on transported fruit in trees and rats building seed caches at their base. Mature trees produced large amounts of viable seed, but rates of seed predation were high. Weevils, beetle larvae and omnivorous vertebrates such as Australian ravens, magpies and introduced black rats were observed eating seeds. The foraging behaviour of the vertebrates may facilitate the dispersal of seeds for relatively long distances away from parent plants. Seeds that escape predation form a transient seed bank and germinate with the onset of the winter rains. Early in their development, seedlings allocate resources to form a large tap‐rooted tuber that has substantial starch and water reserves, allowing seedlings to survive the long dry and hot summers in Perth. The study observed that B. populneus could survive at least one fire by resprouting from basal dormant buds. Brachychiton populneus appears to have become a weed in Kings Park because, first, it is dispersed widely into new sites through the foraging behaviour of vertebrates and once germinated has no grazing pressure, and, second, its development of a root tuber and ability to resprout means the seedlings are resilient in this frequently disturbed Mediterranean environment. While management of existing plants is relatively straightforward, continued vigilance will be required to avoid reinvasion.     

Conversion of 2-fluoromuconate to cis-dienelactone by purified enzymes of Rhodococcus opacus 1cp

The present study describes the (19)F nuclear magnetic resonance analysis of the conversion of 3-halocatechols to lactones by purified chlorocatechol 1,2-dioxygenase (ClcA2), chloromuconate cycloisomerase (ClcB2), and chloromuconolactone dehalogenase (ClcF) from Rhodococcus opacus 1cp grown on 2-chlorophenol. The 3-halocatechol substrates were produced from the corresponding 2-halophenols by either phenol hydroxylase from Trichosporon cutaneum or 2-hydroxybiphenyl 3-mono-oxygenase from Pseudomonas azelaica. Several fluoromuconates resulting from intradiol ring cleavage by ClcA2 were identified. ClcB2 converted 2-fluoromuconate to 5-fluoromuconolactone and 2-chloro-4-fluoromuconate to 2-chloro-4-fluoromuconolactone. Especially the cycloisomerization of 2-fluoromuconate is a new observation. ClcF catalyzed the dehalogenation of 5-fluoromuconolactone to cis-dienelactone. The ClcB2 and ClcF-mediated reactions are in line with the recent finding of a second cluster of chlorocatechol catabolic genes in R. opacus 1cp which provides a new route for the microbial dehalogenation of 3-chlorocatechol.     

Efficient Inhibition of Collagen-Induced Platelet Activation and Adhesion by LAIR-2, a Soluble Ig-Like Receptor Family Member

LAIR-1 (Leukocyte Associated Ig-like Receptor -1) is a collagen receptor that functions as an inhibitory receptor on immune cells. It has a soluble family member, LAIR-2, that also binds collagen and can interfere with LAIR-1/collagen interactions. Collagen is a main initiator for platelet adhesion and aggregation. Here, we explored the potential of soluble LAIR proteins to inhibit thrombus formation in vitro. LAIR-2/Fc but not LAIR-1/Fc inhibited collagen-induced platelet aggregation. In addition, LAIR-2/Fc also interfered with platelet adhesion to collagen at low shear rate (300 s⁻¹; IC₅₀ = 18 µg/ml) and high shear rate (1500 s⁻¹; IC₅₀ = 30 µg/ml). Additional experiments revealed that LAIR-2/Fc leaves interactions between collagen and α2β1 unaffected, but efficiently prevents binding of collagen to Glycoprotein VI and von Willebrand factor. Thus, LAIR-2/Fc has the capacity to interfere with platelet-collagen interactions mediated by Glycoprotein VI and the VWF/Glycoprotein Ib axis.     

Connective Tissue Growth Factor Is Involved in Structural Retinal Vascular Changes in Long-Term Experimental Diabetes

Early retinal vascular changes in the development of diabetic retinopathy (DR) include capillary basal lamina (BL) thickening, pericyte loss and the development of acellular capillaries. Expression of the CCN (connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed) family member CCN2 or connective tissue growth factor (CTGF), a potent inducer of the expression of BL components, is upregulated early in diabetes. Diabetic mice lacking one functional CTGF allele (CTGF^+/−) do not show this BL thickening. As early events in DR may be interrelated, we hypothesized that CTGF plays a role in the pathological changes of retinal capillaries other than BL thickening. We studied the effects of long-term (6-8 months) streptozotocin-induced diabetes on retinal capillary BL thickness, numbers of pericytes and the development of acellular capillaries in wild type and CTGF^+/− mice. Our results show that an absence of BL thickening of retinal capillaries in long-term diabetic CTGF^+/− mice is associated with reduced pericyte dropout and reduced formation of acellular capillaries. We conclude that CTGF is involved in structural retinal vascular changes in diabetic rodents. Inhibition of CTGF in the eye may therefore be protective against the development of DR.     

Nucleocytoplasmic distribution is required for activation of resistance by the potato NB-LRR receptor Rx1 and is balanced by its functional domains

The Rx1 protein, as many resistance proteins of the nucleotide binding-leucine-rich repeat (NB-LRR) class, is predicted to be cytoplasmic because it lacks discernable nuclear targeting signals. Here, we demonstrate that Rx1, which confers extreme resistance to Potato virus X, is located both in the nucleus and cytoplasm. Manipulating the nucleocytoplasmic distribution of Rx1 or its elicitor revealed that Rx1 is activated in the cytoplasm and cannot be activated in the nucleus. The coiled coil (CC) domain was found to be required for accumulation of Rx1 in the nucleus, whereas the LRR domain promoted the localization in the cytoplasm. Analyses of structural subdomains of the CC domain revealed no autonomous signals responsible for active nuclear import. Fluorescence recovery after photobleaching and nuclear fractionation indicated that the CC domain binds transiently to large complexes in the nucleus. Disruption of the Rx1 resistance function and protein conformation by mutating the ATP binding phosphate binding loop in the NB domain, or by silencing the cochaperone SGT1, impaired the accumulation of Rx1 protein in the nucleus, while Rx1 versions lacking the LRR domain were not affected in this respect. Our results support a model in which interdomain interactions and folding states determine the nucleocytoplasmic distribution of Rx1.     

Aggravation of myocardial dysfunction by injurious mechanical ventilation in LPS-induced pneumonia in rats

Background

Mechanical ventilation (MV) may cause ventilator-induced lung injury (VILI) and may thereby contribute to fatal multiple organ failure. We tested the hypothesis that injurious MV of lipopolysaccharide (LPS) pre-injured lungs induces myocardial inflammation and further dysfunction ex vivo, through calcium (Ca²⁺)-dependent mechanism.

Materials and methods

N = 35 male anesthetized and paralyzed male Wistar rats were randomized to intratracheal instillation of 2 mg/kg LPS or nothing and subsequent MV with lung-protective settings (low tidal volume (V_t) of 6 mL/kg and 5 cmH₂O positive end-expiratory pressure (PEEP)) or injurious ventilation (high V_t of 19 mL/kg and 1 cmH₂O PEEP) for 4 hours. Myocardial function ex vivo was evaluated in a Langendorff setup and Ca²⁺ exposure. Key mediators were determined in lung and heart at the mRNA level.

Results

Instillation of LPS and high V_t MV impaired gas exchange and, particularly when combined, increased pulmonary wet/dry ratio; heat shock protein (HSP)70 mRNA expression also increased by the interaction between LPS and high V_t MV. For the heart, C-X-C motif ligand (CXCL)1 and Toll-like receptor (TLR)2 mRNA expression increased, and ventricular (LV) systolic pressure, LV developed pressure, LV +dP/dt_max and contractile responses to increasing Ca²⁺ exposure ex vivo decreased by LPS. High V_t ventilation aggravated the effects of LPS on myocardial inflammation and dysfunction but not on Ca²⁺ responses.

Conclusions

Injurious MV by high V_t aggravates the effects of intratracheal instillation of LPS on myocardial dysfunction, possibly through enhancing myocardial inflammation via pulmonary release of HSP70 stimulating cardiac TLR2, not involving Ca²⁺ handling and sensitivity.