Cations in component reactions of `malic'' enzyme catalysis

The ;malic' enzyme (EC 1.1.1.40) has been purified (300-fold) from wheat germ and its abilities to catalyse the decarboxylation and the hydrogenation of oxaloacetic acid and oxaloacetate esters was studied. The free 1-carboxyl group is essential for the interaction of oxaloacetates and substituted oxaloacetates with the enzyme via cations. The free 4-carboxyl group is required for the decarboxylation but is not indispensable for the hydrogenation. At high concentrations, cations inhibit the enzymic hydrogenation of oxaloacetic acid but not that of 4-ethyl oxaloacetate. A plausible inhibitory mechanism is proposed.     

The plant endosphere world – bacterial life within plants

The plant endosphere is colonized by complex microbial communities and microorganisms, which colonize the plant interior at least part of their lifetime and are termed endophytes. Their functions range from mutualism to pathogenicity. All plant organs and tissues are generally colonized by bacterial endophytes and their diversity and composition depend on the plant, the plant organ and its physiological conditions, the plant growth stage as well as on the environment. Plant-associated microorganisms, and in particular endophytes, have lately received high attention, because of the increasing awareness of the importance of host-associated microbiota for the functioning and performance of their host. Some endophyte functions are known from mostly lab assays, genome prediction and few metagenome analyses; however, we have limited understanding on in planta activities, particularly considering the diversity of micro-environments and the dynamics of conditions. In our review, we present recent findings on endosphere environments, their physiological conditions and endophyte colonization. Furthermore, we discuss microbial functions, the interaction between endophytes and plants as well as methodological limitations of endophyte research. We also provide an outlook on needs of future research to improve our understanding on the role of microbiota colonizing the endosphere on plant traits and ecosystem functioning.     

Keratinocyte-derived Chemokine in Obesity: EXPRESSION, REGULATION, AND ROLE IN ADIPOSE MACROPHAGE INFILTRATION AND GLUCOSE HOMEOSTASIS*

Obese adipose tissue (AT) is associated with chronic inflammation, and we hypothesized that the keratinocyte-derived chemokine (KC), the mouse ortholog of human interleukin-8, plays a role in obesity-mediated AT inflammation and the subsequent manifestation of insulin resistance. KC expression is increased in the AT and plasma of genetically (ob/ob) and high fat diet-induced obese mouse models, and this increase may be mediated by the elevated leptin and tumor necrosis factor-α levels associated with obesity. Obesity-induced KC expression occurs primarily in stromal vascular cells and not in adipocytes, and it is high in preadipocytes and decreases during adipogenesis. Although KC has no effect on adipogenesis, it induces adipocyte expression of inflammatory factors and the insulin resistance mediator, suppressor of cytokine signaling 3. Using chimeric mice deficient in the KC receptor CXCR2 in their bone marrow, we show that the lack of CXCR2 in hematopoietic cells is sufficient to protect from adipose and skeletal muscle macrophage recruitment and development of insulin resistance in diet-induced obese mice. These studies suggest that KC and its receptor CXCR2 are potential targets for the development of new therapeutic approaches for treatment of obesity-related insulin resistance, type II diabetes, and related cardiovascular diseases.Obesity is characterized by systemic low grade inflammation that appears to contribute to the genesis of insulin resistance (IR),³ type 2 diabetes, and increased risk for cardiovascular diseases (reviewed in Ref. 1). Furthermore, adipose tissue (AT) produces a variety of inflammatory factors, and its excessive development in obesity is associated with accumulation of AT macrophages (ATMs) (1), whose recruitment and proinflammatory activation are required for the development of IR in obese mice (reviewed in Ref. 2). An important question concerning ATMs is/are the trigger(s) driving the recruitment of these cells in obesity.Efforts at identifying factors that attract and recruit ATMs have mostly focused on the CC chemokine MCP-1 (monocyte chemoattractant protein-1) and its receptor CCR2. These studies have led to contradicting results with several publications showing that MCP-1 and CCR2 are important for ATM recruitment and the subsequent development of IR (3–5), whereas others show no involvement of this chemokine and its receptor in these processes (6–8). Furthermore, the studies that claim a role for MCP-1 and CCR2 in ATM recruitment and IR show that deficiency of the ligand or the receptor did not result in normalization of ATM content, indicating that other factors also participate in ATM recruitment. These findings suggest that the precise role of the MCP-1/CCR2 axis in ATM recruitment and IR is unclear, and that other chemokines and their receptors could also play a role in these processes. One such chemokine is interleukin 8 (IL-8), the prototypical CXC chemokine known to recruit and activate monocytes and to attract polymorphonuclear leukocytes to sites of inflammation (9). IL-8 is elevated in plasma of obese subjects (10, 11) and correlates with adiposity and insulin sensitivity, suggesting an involvement of this chemokine in obesity-related health complications (12–14). Additionally, IL-8 is implicated in the pathogenesis of atherosclerosis and cardiovascular disease, two obesity-associated disorders (15). Finally, IL-8 is an angiogenic factor, and angiogenesis is a hallmark of AT expansion in obesity (16). Although these findings suggest an important role for IL-8 in AT biology and pathology, little is known regarding the mechanism of regulation of IL-8 in obesity and its role in AT biology and pathology. This is probably due, in part, to the absence of suitable animal models because mice and rats do not have a clear-cut IL-8 ortholog (17).Although rodent keratinocyte-derived chemokine (KC) shows the highest homology with human growth-related oncogene (GRO-α), it appears to be the closest equivalent to IL-8, as judged by its pattern of expression and putative function (18). Monocytes express the KC receptor (CXCR2), and KC triggers monocyte arrest on early atherosclerotic endothelium, one of the first steps in the invasion of tissues by macrophages (19). Interaction of monocyte CXCR2 with its ligand KC leads to up-regulation of α₄β₁ integrin affinity and firm adhesion to the endothelium (19). Furthermore, both KC and its receptor play a central role in macrophage infiltration and accumulation in atherosclerotic lesions in mice (20, 21). However, no information is currently available regarding the role of KC in macrophage recruitment in obese AT or its role in AT biology and pathology.In this study, we show that KC expression is elevated in AT and plasma of genetically (ob/ob) and diet-induced obese (DIO) mice, probably as the result of increased leptin and tumor necrosis factor α (TNF-α) levels associated with obesity. We also show that obesity-induced KC is mostly derived from nonadipocyte sources in AT and that KC does not affect adipocyte differentiation but does increase pro-inflammatory cytokine expression in adipocytes. Finally, we show in a DIO model in chimeric mice lacking CXCR2 on their macrophages that the KC receptor plays an important role in macrophage accumulation in adipose and skeletal muscle tissue and subsequent development of IR.     

Association of admission testosterone level with ST-segment resolution in male patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background

Low level of testosterone may be associated with cardiovascular diseases in men, as some evidence suggests a protective role for testosterone in cardiovascular system. Little is known about the possible role of serum testosterone in response to reperfusion therapy in ST-elevation myocardial infarction (STEMI) and its relationship with ST-segment recovery. The present study was conducted to evaluate the association of serum testosterone levels with ST-segment resolution following primary percutaneous coronary intervention (PPCI) in male patients with acute STEMI.

Methods

Forty-eight men (mean age 54.55 ± 12.20) with STEMI undergoing PPCI were enrolled prospectively. Single-lead ST segment resolution in the lead with maximum baseline ST-elevation was measured and patients were divided into two groups according to the degree of ST-segment resolution: complete (> or =50%) or incomplete (<50%). The basic and demographic data of all patients, their left ventricular ejection fraction (LVEF) and laboratory findings including serum levels of free testosterone and cardiac enzymes were recorded along with angiographic finding and baseline TIMI (Thrombolysis in Myocardial Infarction) flow and also in-hospital complications and then these variables were compared between two groups.

Results

A complete ST-resolution (≥50%) was observed in 72.9% of the patients. The serum levels of free testosterone (P = 0.04), peak cardiac troponin (P = 0.03) were significantly higher and hs-CRP (P = 0.02) were lower in patients with complete ST-resolution compared to those with incomplete ST-resolution. In-hospital complications were observed in 31.2% of patients. The patients with a lower baseline TIMI flow (P = 0.03) and those who developed complications (P = 0.04) had lower levels of free testosterone. A significant positive correlation was observed between the left ventricular function and serum levels of free testosterone (P = 0.01 and r = +0.362).

Conclusion

This study suggests that in men with STEMI undergoing PPCI, higher serum levels of testosterone are associated with a better reperfusion response, fewer complications and a better left ventricular function.

     

Identification of GABA A receptor modulators in Kadsura longipedunculata and assignment of absolute configurations by quantum-chemical ECD calculations

A petroleum ether extract of Kadsura longipedunculata enhanced the GABA-induced chloride current (I_GABA) by 122.5 ± 0.3% (n = 2) when tested at 100 μg/ml in Xenopuslaevis oocytes expressing GABA A receptors (α₁β₂γ_2S subtype) in two-microelectrode voltage clamp measurements. Thirteen compounds were subsequently identified by HPLC-based activity profiling as responsible for GABA A receptor activity and purified in preparative scale. 6-Cinnamoyl-6,7-dihydro-7-myrceneol and 5,6-dihydrocuparenic acid were thereby isolated for the first time. The determination of the absolute stereochemistry of these compounds was achieved by comparison of experimental and calculated ECD spectra. All but one of the 13 isolated compounds from K. longipedunculata potentiated I_GABA through GABA A receptors composed of α₁β₂γ_2S subunits in a concentration-dependent manner. Potencies ranged from 12.8 ± 3.1 to 135.6 ± 85.7 μM, and efficiencies ranged from 129.7 ± 36.8% to 885.8 ± 291.2%. The phytochemical profiles of petroleum ether extracts of Kadsura japonica fruits (114.1 ± 2.6% potentiation of I_GABA at 100 μg/ml, n = 2), and Schisandra chinensis fruits (inactive at 100 μg/ml) were compared by HPLC-PDA-ESIMS with that of K. longipedunculata.     

Dragon (repulsive guidance molecule b) inhibits IL-6 expression in macrophages

Despite the strong interest in the NK cell-mediated immunity toward malignant cells and viruses, there is a relative lack of data on the interplay between NK cells and filamentous fungi, especially Aspergillus fumigatus, which is the major cause of invasive aspergillosis. By studying the in vitro interaction between human NK cells and A. fumigatus, we found only germinated morphologies to be highly immunogenic, able to induce a Th1-like response, and capable of upregulating cytokines such as IFN-γ and TNF-α. Moreover, priming NK cells with human rIL-2 and stimulating NK cells by direct NK cell-pathogen contact were essential to induce damage against A. fumigatus. However, the most interesting finding was that NK cells did not mediate anti-Aspergillus cytotoxicity through degranulation of their cytotoxic proteins (perforin, granzymes, granulysine), but via an alternative mechanism involving soluble factor(s). To our knowledge, our study is the first to demonstrate that IFN-γ, released by NK cells, directly damages A. fumigatus, attributing new properties to both human NK cells and IFN-γ and suggesting them as possible therapeutic tools against IA.     

Phylogenetic diversity and genome sizes of Astragalus (Fabaceae) in the Lebanon biogeographical crossroad

The Lebanese mountain range is an important zone of plant species richness and endemism where the genus Astragalus constitutes a principal component of plant biodiversity. Most of endemic Astragalus taxa, living in mountains and arid zones of Mounts Lebanon and anti-Lebanon, are characterized by a cushion, spiny vegetative form, named “tragacanthic”, which is a remarkable example of vegetative convergence evolution. Because of determination difficulties, taxonomic uncertainties, and discrepancy in the number of taxa listed according to authors, new data are hardly needed to improve systematics of Astragalus and to investigate the role of the Lebanese mountain range as refugia of biodiversity. Before this study only two values on the genome size of Astragalus were reported in the literature and no previous molecular studies had been carried out on Astragalus genus in Lebanon. We examined the utility of rDNA ITS molecular markers to distinguish Astragalus species of Lebanese mountain range and the variation range of their genome size. The main results revealed a striking diversity in Lebanese Astragalus species with the emphasis of a huge variation of genome sizes, an important inter-specific chromosome polymorphism and the existence of a high phylogenetic diversity. The strict endemic species of the Lebanese mountains are positioned throughout the phylogeny. These results confirm that the Lebanon and anti-Lebanon mounts constitute a third diversity center for Astragalus and that high altitude areas are important refugia of plant biodiversity despite centuries of exploitation by humans.     

A new pharmacological role for donepezil: attenuation of morphine-induced tolerance and apoptosis in rat central nervous system

Background

Tolerance to the analgesic effect of opioids is a pharmacological phenomenon that occurs after their prolonged administration. It has been shown that morphine-induced tolerance is associated with apoptosis in the central nervous system and neuroprotective agents which prevented apoptosis signaling could attenuate tolerance to the analgesic effects. On the other hand donepezil, an acetylcholinesterase inhibitor, has been reported to have neuroprotective effects. Therefore in this study, the effect of systemic administration of donepezil on morphine-induced tolerance and apoptosis in the rat cerebral cortex and lumbar spinal cord was evaluated. Various groups of rats received morphine (ip) and different doses of donepezil (0, 0.5, 1, 1.5 mg/kg/day). Nociception was assessed using tail flick apparatus. Tail flick latency was recorded when the rat shook its tail. For apoptosis assay other groups of rats received the above treatment and apoptosis was evaluated by in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method.

Results

The results showed that administration of donepezil (0.5, 1, 1.5 mg/kg, ip) delayed the morphine tolerance for 9, 12 and 17 days, respectively. Furthermore pretreatment injection of donepezil attenuated the number of apoptotic cells in the cerebral cortex and lumbar spinal cord compared to the control group.

Conclusion

In conclusion, we found that systemic administration of donepezil attenuated morphine-induced tolerance and apoptosis in the rat cerebral cortex and lumbar spinal cord.