Androgen-mediated modulation of macrophage function after trauma-hemorrhage: central role of 5alpha-dihydrotestosterone.

Androgens have been implicated as the causative factor for the postinjury immune dysfunction in males; however, it remains unknown whether androgens directly affect macrophages. To study this, male mice were sham operated or subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (mean arterial pressure, 30 +/- 5 mmHg for 90 min and then resuscitated). The mice received the 5alpha-reductase inhibitor 4-hydroxyandrostenedione (4-OHA) before resuscitation. Plasma TNF-alpha, IL-6, and IL-10 levels were elevated after trauma-hemorrhage and normalized by 4-OHA. TNF-alpha and IL-6 production by splenic macrophages was decreased after injury, whereas Kupffer cell production of these mediators was enhanced. 4-OHA normalized cytokine production. Androgens suppressed cytokine production by splenic macrophages from hemorrhaged mice, whereas it enhanced TNF-alpha and IL-6 production by Kupffer cells. The addition of 4-OHA in vitro normalized cytokine production by cells treated with testosterone, but it had no effect on dihydrotestosterone-treated cells. These results indicate that androgens directly affect macrophage function in males after trauma and hemorrhagic shock and that the intracellular conversion of testosterone to dihydrotestosterone is of particular importance in mediating the androgen-induced effects.     

Predicting the Potential Future Distribution of Four Tree Species in Ohio Using Current Habitat Availability and Climatic Forcing

Weinvestigated the effect of habitat loss on the ability of trees to shift in distribution across a landscape dominated by agriculture. The potential distribution shifts of four tree species (Diospyros virginiana, Oxydendron arboreum, Pinus virginiana, Quercus falcata var. falcata) whose northern distribution limits fall in the southern third of Ohio were used to assess possible distribution shift scenarios as a result of global warming. Our predictions derive from the results of simulations using (a) forest inventory based estimates of current distribution and abundance of target species; (b) a satellite-based estimate of forest habitat availability; and (c) a tree migration model (SHIFT). The current distribution and abundance of trees was estimated using USDA Forest Service's Forest Inventory Analysis data and distribution maps from the late 1960s; pre-European settlement forest–nonforest maps were used to represent the fully forested condition for calibration and comparison. Habitat-availability estimates in Ohio were estimated using classified Landsat Thematic Mapper (TM) data from 1994. Tree abundance, forest availability and migration were modeled using a 1-km² pixel size. Forest availability was estimated as the proportion of forested TM pixels within each cell. The probability of a migrating species colonizing an unoccupied cell is modeled as a function of forest availability and distance to occupied cells. The results of the migration models suggest that the species studied are capable of colonizing virtually any forested location within Ohio over the next 100 years if climatic controls over the current distribution that may currently inhibit northward movement are relaxed. The contiguous distribution of these species, however, is not likely to shift more than 10 km during the next century regardless of the magnitude of the climate change. Examining the sensitivity of our simulations by varying critical model attributes, we found that whereas the variables controlling the amount of long-distance dispersal have strong effects on migration rates in the fully forested 1800 situation, they have significantly lesser effects on projections of future migration into highly fragmented forests. The low forest availability that characterizes much of the current Ohio landscape, along with the low likelihood of long distance dispersal, result in potential distribution shifts that are concentrated within the principally forested corridors in southeastern Ohio. We propose that in contrast to the past, future tree migrations are likely to be spatially and temporally correlated as a result of large climatic forcing and channelization through limited regions of available habitat. With respect to the management of biodiversity, this result suggests that it may be very difficult to discern plant migrations of native forest species owing to exceedingly slow rates of movement. Received 19 September 2000; Accepted 2 March 2001.     

Novel thieno oxazine analogues as antihyperglycemic and lipid modulating agents

A series of phenyl acetic acid and alpha-hydroxy propionic acid derivatives were synthesized. In vivo studies of the compounds indicated compound 2c as the most potent in one of the series, which has both glucose and lipid lowering properties. The syntheses and biological studies have been discussed.     

Utilizing the density of inventory samples to define a hybrid lattice for species distribution models: DISTRIB‐II for 135 eastern U.S. trees

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Total synthesis of phenylpropanoid glycosides, grayanoside A and syringalide B, through a common intermediate

Phenylpropanoid glycosides are known as bioactive natural products. Two of them, grayanoside A (1) and syringalide B (2), were synthesized through a common intermediate, using benzyl as temporary protecting group following a shorter route.     

Influence of poly(ethylene glycol) grafting density and polymer length on liposomes: Relating plasma circulation lifetimes to protein binding

The incorporation of poly(ethylene glycol) (PEG)-conjugated lipids in lipid-based carriers substantially prolongs the circulation lifetime of liposomes. However, the mechanism(s) by which PEG-lipids achieve this have not been fully elucidated. It is believed that PEG-lipids mediate steric stabilization, ultimately reducing surface-surface interactions including the aggregation of liposomes and/or adsorption of plasma proteins. The purpose of the studies described here was to compare the effects of PEG-lipid incorporation in liposomes on protein binding, liposome-liposome aggregation and pharmacokinetics in mice. Cholesterol-free liposomes were chosen because of their increasing importance as liposomal delivery systems and their marked sensitivity to protein binding and aggregation. Specifically, liposomes containing various molecular weight PEG-lipids at a variety of molar proportions were analyzed for in vivo clearance, aggregation state (size exclusion chromatography, quasi-elastic light scattering, cryo-transmission and freeze fracture electron microscopy) as well as in vitro and in vivo protein binding. The results indicated that as little as 0.5 mol% of 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE) modified with PEG having a mean molecular weight of 2000 (DSPE-PEG₂₀₀₀) substantially increased plasma circulation longevity of liposomes prepared of 1,2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC). Optimal plasma circulation lifetimes could be achieved with 2 mol% DSPE-PEG₂₀₀₀. At this proportion of DSPE-PEG₂₀₀₀, the aggregation of DSPC-based liposomes was completely precluded. However, the total protein adsorption and the protein profile was not influenced by the level of DSPE-PEG₂₀₀₀ in the membrane. These studies suggest that PEG-lipids reduce the in vivo clearance of cholesterol-free liposomal formulations primarily by inhibition of surface interactions, particularly liposome-liposome aggregation.     

Neuronal suppressor of cytokine signaling-3 deficiency enhances hypothalamic leptin-dependent phosphatidylinositol 3-kinase signaling

Suppressor of cytokine signaling-3 (SOCS3) is thought to be involved in the development of central leptin resistance and obesity by inhibiting STAT3 pathway. Because phosphatidylinositol 3-kinase (PI3K) pathway plays an important role in transducing leptin action in the hypothalamus, we examined whether SOCS3 exerted an inhibition on this pathway. We first determined whether leptin sensitivity in the hypothalamic PI3K pathway was increased in brain-specific Socs3-deficient (NesKO) mice. In NesKO mice, hypothalamic insulin receptor substrate-1 (IRS1)-associated PI3K activity was significantly increased at 30 min and remained elevated up to 2 h after leptin intraperitoneal injection, but in wild-type (WT) littermates, the significant increase was only at 30 min. Hypothalamic p-STAT3 levels were increased up to 5 h in NesKO as opposed to 2 h in WT mice. In food-restricted WT mice with reduced body weight, leptin increased hypothalamic PI3K activity only at 30 min, and p-STAT3 levels at 30-120 min postinjection. These results suggest increased leptin sensitivity in both PI3K and STAT3 pathways in the hypothalamus of NesKO mice, which was not due to a lean phenotype. In the next experiment with a clonal hypothalamic neuronal cell line expressing proopiomelanocortin, we observed that whereas leptin significantly increased IRS1-associated PI3K activity and p-JAK2 levels in cells transfected with control vector, it failed to do so in SOCS3-overexpressed cells. Altogether, these results imply a SOCS3 inhibition of the PI3K pathway of leptin signaling in the hypothalamus, which may be one of the mechanisms behind the development of central leptin resistance and obesity.     

N-end rule pathway inhibitor sensitizes cancer cells to antineoplastic agents by regulating XIAP and RAD21 protein expression

Anticancer drugs exert their effects on cancer cells by deregulating many pathways linked to cell cycle, apoptosis, etc. but cancer cells gradually become resistive against anticancer drugs, thereby necessitating the development of newer generation anticancer molecules. N-end rule pathway has been shown to be involved in the degradation of many cell cycle and apoptosis-related proteins. However, the involvements of this pathway in cancer are not well established. Recently, we developed a non-peptide-based N-end rule pathway inhibitor, RF-C11 for type 1 and 2 recognition domains of E3 ubiquitin ligases. The inhibitor significantly increased the half-life of potential N-degrons leading to significant physiological changes in vivo. We hypothesized RF-C11 may be used to decipher the N-end rule pathway's role in cancer towards the development of anticancer therapeutics. In this study, we showed that RF-C11, barring noncancer cells, significantly sensitizes cancer cells towards different anticancer agents tested. We further find that the profound cellular sensitization to anticancer drugs was affected by (a) downregulation of X-linked inhibitor of apoptosis protein, an antiapoptotic protein and (b) by stabilization of RAD21, and thereby inhibiting metaphase to anaphase promotion. The study shows that RF-C11 or its analogs may be used as a novel additive in combination therapy against cancer.