The genetic architecture of branched-chain amino acid accumulation in tomato fruits

Previous studies of the genetic architecture of fruit metabolic composition have allowed us to identify four strongly conserved co-ordinate quantitative trait loci (QTL) for the branched-chain amino acids (BCAAs). This study has been extended here to encompass the other 23 enzymes described to be involved in the pathways of BCAA synthesis and degradation. On coarse mapping the chromosomal location of these enzymes, it was possible to define the map position of 24 genes. Of these genes eight co-localized, or mapped close to BCAA QTL including those encoding ketol-acid reductoisomerase (KARI), dihydroxy-acid dehydratase (DHAD), and isopropylmalate dehydratase (IPMD). Quantitative evaluation of the expression levels of these genes revealed that the S. pennellii allele of IPMD demonstrated changes in the expression level of this gene, whereas those of KARI and DHAD were invariant across the genotypes. Whilst the antisense inhibition of IPMD resulted in increased BCAA, the antisense inhibition of neither KARI nor DHAD produced a clear effect in fruit BCAA contents. The results are discussed both with respect to the roles of these specific enzymes within plant amino acid metabolism and within the context of current understanding of the regulation of plant branched-chain amino acid metabolism

Histone Deacetylases Regulate Gonadotropin-Releasing Hormone I Gene Expression via Modulating Otx2-Driven Transcriptional Activity

BACKGROUND: Precise coordination of the hypothalamic-pituitary-gonadal axis orchestrates the normal reproductive function. As a central regulator, the appropriate synthesis and secretion of gonadotropin-releasing hormone I (GnRH-I) from the hypothalamus is essential for the coordination. Recently, emerging evidence indicates that histone deacetylases (HDACs) play an important role in maintaining normal reproductive function. In this study, we identify the potential effects of HDACs on Gnrh1 gene transcription. METHODOLOGY/PRINCIPAL FINDINGS: Inhibition of HDACs activities by trichostatin A (TSA) and valproic acid (VPA) promptly and dramatically repressed transcription of Gnrh1 gene in the mouse immortalized mature GnRH neuronal cells GT1-7. The suppression was connected with a specific region of Gnrh1 gene promoter, which contains two consensus Otx2 binding sites. Otx2 has been known to activate the basal and also enhancer-driven transcription of Gnrh1 gene. The transcriptional activity of Otx2 is negatively modulated by Grg4, a member of the Groucho-related-gene (Grg) family. In the present study, the expression of Otx2 was downregulated by TSA and VPA in GT1-7 cells, accompanied with the opposite changes of Grg4 expression. Chromatin immunoprecipitation and electrophoretic mobility shift assays demonstrated that the DNA-binding activity of Otx2 to Gnrh1 gene was suppressed by TSA and VPA. Overexpression of Otx2 partly abolished the TSA- and VPA-induced downregulation of Gnrh1 gene expression. CONCLUSIONS/SIGNIFICANCE: Our data indicate that HDAC inhibitors downregulate Gnrh1 gene expression via repressing Otx2-driven transcriptional activity. This study should provide an insight for our understanding on the effects of HDACs in the reproductive system and suggests that HDACs could be potential novel targets for the therapy of GnRH-related diseases

Synthesis of a Dual Functional Anti-MDR Tumor Agent PH II-7 with Elucidations of Anti-Tumor Effects and Mechanisms

Multidrug resistance mediated by P-glycoprotein in cancer cells has been a major issue that cripples the efficacy of chemotherapy agents. Aimed for improved efficacy against resistant cancer cells, we designed and synthesized 25 oxindole derivatives based on indirubin by structure-activity relationship analysis. The most potent one was named PH II-7, which was effective against 18 cancer cell lines and 5 resistant cell lines in MTT assay. It also significantly inhibited the resistant xenograft tumor growth in mouse model. In cell cycle assay and apoptosis assay conducted with flow cytometry, PH II-7 induced S phase cell cycle arrest and apoptosis even in resistant cells. Consistently revealed by real-time PCR, it modulates the expression of genes related to the cell cycle and apoptosis in these cells, which may contributes to its efficacy against them. By side-chain modification and FITC-labeling of PH II-7, we were able to show with confocal microscopy that not only it was not pumped by P-glycoprotein, it also attenuated the efflux of Adriamycin by P-glycoprotein in MDR tumor cells. Real-time PCR and western blot analysis showed that PH II-7 down-regulated MDR1 gene via protein kinase C alpha (PKCA) pathway, with c-FOS and c-JUN as possible mediators. Taken together, PH II-7 is a dual-functional compound that features both the cytotoxicity against cancer cells and the inhibitory effect on P-gp mediated drug efflux

The impact of inflammation on bone mass in children

Bone is a dynamic tissue. Skeletal bone integrity is maintained through bone modeling and remodeling. The mechanisms underlying this bone mass regulation are complex and interrelated. An imbalance in the regulation of bone remodeling through bone resorption and bone formation results in bone loss. Chronic inflammation influences bone mass regulation. Inflammation-related bone disorders share many common mechanisms of bone loss. These mechanisms are ultimately mediated through the uncoupling of bone remodeling. Cachexia, physical inactivity, pro-inflammatory cytokines, as well as iatrogenic factors related to effects of immunosuppression are some of the common mechanisms. Recently, cytokine signaling through the central nervous system has been investigated for its potential role in bone mass dysregulation in inflammatory conditions. Growing research on the molecular mechanisms involved in inflammation-induced bone loss may lead to more selective therapeutic targeting of these pathological signaling pathways

Antibacterial activity of sucralfate versus aluminum chloride in simulated gastric fluid

Studies have previously demonstrated that sucralfate possesses intrinsic antibacterial activity. This study was designed to indirectly assess whether aluminum is the active antibacterial component of sucralfate and to further evaluate factors that may influence this agent's antibacterial activity. Utilizing an in vitro model, the antibacterial activity of sucralfate, an equivalent quantity of aluminum in the form of aluminum chloride, and a control were compared. In addition, the influences of bacterial species ( Enterobacter cloacae and Pseudomonas aeruginosa ), time (0–24 h) and environmental pH (3, 5, 7) on the agents' antibacterial activities were evaluated. Equivalent quantities of aluminum, as either sucralfate or aluminum chloride, were added to two of three flasks containing approximately 10 5 cfu/ml of bacteria in pH-adjusted simulated gastric fluid. The third flask served as a control. Samples were obtained over 24 h, diluted and subcultured onto agar plates. The experiments demonstrated that bacterial growth was influenced by pH, time and treatment (aluminum chloride or sucralfate). Regardless of pH or bacterial species, bacterial death occurred within 20 min following the addition of aluminum chloride. In contrast, bacterial death following the addition of sucralfate was more variable and appeared to be pH dependent. In conclusion, sucralfate and aluminum chloride both possess antibacterial activity, even at pH values that normally support bacterial growth in gastric fluid. Although differences in the antibacterial activity of the two agents may in part be related to drug-induced changes in pH, these differences also support data suggesting that aluminum release from sucralfate is incomplete and is dependent on pH.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47895/1/10096_2005_Article_BF02111825.pd

Urticaria and infections

Urticaria is a group of diseases that share a distinct skin reaction pattern. Triggering of urticaria by infections has been discussed for many years but the exact role and pathogenesis of mast cell activation by infectious processes is unclear. In spontaneous acute urticaria there is no doubt for a causal relationship to infections and all chronic urticaria must have started as acute. Whereas in physical or distinct urticaria subtypes the evidence for infections is sparse, remission of annoying spontaneous chronic urticaria has been reported after successful treatment of persistent infections. Current summarizing available studies that evaluated the course of the chronic urticaria after proven Helicobacter eradication demonstrate a statistically significant benefit compared to untreated patients or Helicobacter-negative controls without urticaria (p < 0.001). Since infections can be easily treated some diagnostic procedures should be included in the routine work-up, especially the search for Helicobacter pylori. This review will update the reader regarding the role of infections in different urticaria subtypes