310 research outputs found

    The HY5-PIF regulatory module coordinates light and temperature control of photosynthetic gene transcription

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    The ability to interpret daily and seasonal alterations in light and temperature signals is essential for plant survival. This is particularly important during seedling establishment when the phytochrome photoreceptors activate photosynthetic pigment production for photoautotrophic growth. Phytochromes accomplish this partly through the suppression of phytochrome interacting factors (PIFs), negative regulators of chlorophyll and carotenoid biosynthesis. While the bZIP transcription factor long hypocotyl 5 (HY5), a potent PIF antagonist, promotes photosynthetic pigment accumulation in response to light. Here we demonstrate that by directly targeting a common promoter cis-element (G-box), HY5 and PIFs form a dynamic activation-suppression transcriptional module responsive to light and temperature cues. This antagonistic regulatory module provides a simple, direct mechanism through which environmental change can redirect transcriptional control of genes required for photosynthesis and photoprotection. In the regulation of photopigment biosynthesis genes, HY5 and PIFs do not operate alone, but with the circadian clock. However, sudden changes in light or temperature conditions can trigger changes in HY5 and PIFs abundance that adjust the expression of common target genes to optimise photosynthetic performance and growth

    Amelioration of endotoxemia by a synthetic analog of Omega-3 epoxyeicosanoids

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    Sepsis, a systemic inflammatory response to pathogenic factors, is a difficult to treat life-threatening condition associated with cytokine and eicosanoid storms and multi-organ damage. Omega-3 polyunsaturated fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic acid, are the precursors of potent anti-inflammatory lipid mediators, including 17,18-epoxyeicosatetraenoic acid (17,18-EEQ), the main metabolite of EPA generated by cytochrome P450 epoxygenases. Searching for novel therapeutic or preventative agents in sepsis, we tested a metabolically robust synthetic analog of 17,18-EEQ (EEQ-A) for its ability to reduce mortality, organ damage, and pro-inflammatory cytokine transcript level in a mouse model of lipopolysaccharide (LPS)-induced endotoxemia, which is closely related to sepsis. Overall survival significantly improved following preventative EEQ-A administration along with decreased transcript level of pro-inflammatory cytokines. On the other hand, the therapeutic protocol was effective in improving survival at 48 hours but insignificant at 72 hours. Histopathological analyses showed significant reductions in hemorrhagic and necrotic damage and infiltration in the liver. In vitro studies with THP-1 and U937 cells showed EEQ-A mediated repression of LPS-induced M1 polarization and enhancement of IL-4-induced M2 polarization of macrophages. Moreover, EEQ-A attenuated the LPS-induced decline of mitochondrial function in THP-1 cells, as indicated by increased basal respiration and ATP production as well as reduction of the metabolic shift to glycolysis. Taken together, these data demonstrate that EEQ-A has potent anti-inflammatory and immunomodulatory properties that may support therapeutic strategies for ameliorating the endotoxemia

    Microsatellite diversity and genetic structure among common bean (Phaseolus vulgaris L.) landraces in Brazil, a secondary center of diversity

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    Brazil is the largest producer and consumer of common bean (Phaseolus vulgaris L.), which is the most important source of human dietary protein in that country. This study assessed the genetic diversity and the structure of a sample of 279 geo-referenced common bean landraces from Brazil, using molecular markers. Sixty-seven microsatellite markers spread over the 11 linkage groups of the common bean genome, as well as Phaseolin, PvTFL1y, APA and four SCAR markers were used. As expected, the sample showed lower genetic diversity compared to the diversity in the primary center of diversification. Andean and Mesoamerican gene pools were both present but the latter gene pool was four times more frequent than the former. The two gene pools could be clearly distinguished; limited admixture was observed between these groups. The Mesoamerican group consisted of two sub-populations, with a high level of admixture between them leading to a large proportion of stabilized hybrids not observed in the centers of domestication. Thus, Brazil can be considered a secondary center of diversification of common bean. A high degree of genome-wide multilocus associations even among unlinked loci was observed, confirming the high level of structure in the sample and suggesting that association mapping should be conducted in separate Andean and Mesoamerican Brazilian samples

    Age, gender, will, and use of home-visit nursing care are critical factors in home care for malignant diseases; a retrospective study involving 346 patients in Japan

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    <p>Abstract</p> <p>Background</p> <p>We aimed to clarify the factors affecting outcomes of home care for patients with malignant diseases.</p> <p>Methods</p> <p>Of 607 patients who were treated in 10 clinics specialized in home care between January and December 2007 at Chiba, Fukuoka, Iwate, Kagoshima, Tochigi and Tokyo prefectures across Japan, 346 (57%; 145 men and 201 women) had malignant diseases. We collected information on medical and social backgrounds, details of home care, and its outcomes based on their medical records.</p> <p>Results</p> <p>Median age of the patients was 77 years (range, 11-102), and 335 patients were economically self-sufficient. Their general condition was poor; advanced cancer (n = 308), performance status of 3-4 (n = 261), and dementia (n = 121). At the beginning of home care, 143 patients and 174 family members expressed their wish to die at home. All the patients received supportive treatments including fluid replacement and oxygenation. Median duration of home care was 47 days (range, 0-2,712). 224 patients died at home. For the remaining 122, home care was terminated due to complications (n = 109), change of attending physicians (n = 8), and others (n = 5). The factors which inhibited the continuity of home care were the non-use of home-visit nursing care (hazard ratio [HR] = 1.78, 95% confidence interval [CI]: 1.05-3.00, <it>p </it>= 0.03), the fact that the patients themselves do not wish to die at home (HR = 1.83, CI: 1.09-3.07, <it>p </it>= 0.02), women (HR = 1.81, CI: 1.11-2.94, <it>p </it>= 0.02), and age (HR = 0.98, CI: 0.97-1.00, <it>p </it>= 0.02).</p> <p>Conclusions</p> <p>Continuation of home care is influenced by patients' age, gender, will, and use of home-visit nursing.</p

    Degradation of Host Sphingomyelin Is Essential for Leishmania Virulence

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    In eukaryotes, sphingolipids (SLs) are important membrane components and powerful signaling molecules. In Leishmania, the major group of SLs is inositol phosphorylceramide (IPC), which is common in yeast and Trypanosomatids but absent in mammals. In contrast, sphingomyelin is not synthesized by Leishmania but is abundant in mammals. In the promastigote stage in vitro, Leishmania use SL metabolism as a major pathway to produce ethanolamine (EtN), a metabolite essential for survival and differentiation from non-virulent procyclics to highly virulent metacyclics. To further probe SL metabolism, we identified a gene encoding a putative neutral sphingomyelinase (SMase) and/or IPC hydrolase (IPCase), designated ISCL (Inositol phosphoSphingolipid phospholipase C-Like). Despite the lack of sphingomyelin synthesis, L. major promastigotes exhibited a potent SMase activity which was abolished upon deletion of ISCL, and increased following over-expression by episomal complementation. ISCL-dependent activity with sphingomyelin was about 20 fold greater than that seen with IPC. Null mutants of ISCL (iscl−) showed modest accumulation of IPC, but grew and differentiated normally in vitro. Interestingly, iscl− mutants did not induce lesion pathology in the susceptible BALB/c mice, yet persisted indefinitely at low levels at the site of infection. Notably, the acute virulence of iscl− was completely restored by the expression of ISCL or heterologous mammalian or fungal SMases, but not by fungal proteins exhibiting only IPCase activity. Together, these findings strongly suggest that degradation of host-derived sphingomyelin plays a pivotal role in the proliferation of Leishmania in mammalian hosts and the manifestation of acute disease pathology

    Protein Kinase A Dependent Phosphorylation of Apical Membrane Antigen 1 Plays an Important Role in Erythrocyte Invasion by the Malaria Parasite

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    Apicomplexan parasites are obligate intracellular parasites that infect a variety of hosts, causing significant diseases in livestock and humans. The invasive forms of the parasites invade their host cells by gliding motility, an active process driven by parasite adhesion proteins and molecular motors. A crucial point during host cell invasion is the formation of a ring-shaped area of intimate contact between the parasite and the host known as a tight junction. As the invasive zoite propels itself into the host-cell, the junction moves down the length of the parasite. This process must be tightly regulated and signalling is likely to play a role in this event. One crucial protein for tight-junction formation is the apical membrane antigen 1 (AMA1). Here we have investigated the phosphorylation status of this key player in the invasion process in the human malaria parasite Plasmodium falciparum. We show that the cytoplasmic tail of P. falciparum AMA1 is phosphorylated at serine 610. We provide evidence that the enzyme responsible for serine 610 phosphorylation is the cAMP regulated protein kinase A (PfPKA). Importantly, mutation of AMA1 serine 610 to alanine abrogates phosphorylation of AMA1 in vivo and dramatically impedes invasion. In addition to shedding unexpected new light on AMA1 function, this work represents the first time PKA has been implicated in merozoite invasion

    Clinical and prognostic analysis of hepatitis B virus infection in diffuse large B-cell lymphoma

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    <p>Abstract</p> <p>Background</p> <p>Hepatitis B virus (HBV) infection in diffuse large B-cell lymphoma (DLBCL) patients is a common complication in China. However, the clinical relevance of HBV infection with respect to DLBCL disease stages and patient survival remains unclear. The main objective of the current study was to analyze the clinical features and to evaluate the prognostic factors of HBV infection in DLBCL patients.</p> <p>Methods</p> <p>In this retrospective study, DLBCL patients were divided into two groups as HBsAg-positive (n = 81) and HBsAg-negative (n = 181) patients. The HBsAg-positive patients were further divided into two subgroups based on their hepatic function during chemotherapy. Various statistical analyses were used to determine the significance of the relevant clinical parameters.</p> <p>Results</p> <p>Compared with the HBsAg-negative group, the HBsAg-positive DLBCL group displayed a younger median onset age (46 year vs 51), more advanced stage at grade III/IV (58% vs 42%, p = 0.016), and more frequent hepatic dysfunction before (21% vs 5.5%, p < 0.001) and during (49.4% vs 16.6%, p < 0.001) chemotherapy. Female DLBCL patients exhibited a higher frequency of HBsAg positivity (p = 0.006). However, in both groups the median overall survival (OS) duration (55.8 vs 66.8 months) and response rates (91% vs 90.4%) were similar. In the HBsAg-positive DLBCL group, the poor prognostic factors were advanced stage (p < 0.001) and hepatic dysfunction during chemotherapy (p = 0.02). The OS of HBsAg-positive patients with hepatic dysfunction during chemotherapy was significantly shorter than those without liver dysfunction (p = 0.016), and the OS rates at 3 years were 48% and 72%, respectively. The use of rituximab did not increase the rates of liver dysfunction in HBsAg-positive DLBCL patients.</p> <p>Conclusion</p> <p>Compared with HBsAg-negative patients, the HBsAg-positive DLBCL patients had earlier onset and more advanced stage. The disease stage and hepatic dysfunction during chemotherapy and were two significant prognostic factors in the HBsAg-positive DLBCL patients. This study suggests that prophylactic treatment of HBV may be of great importance in the cases of HBsAg-positive patients.</p

    Apoptosis in cancer: from pathogenesis to treatment

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    Apoptosis is an ordered and orchestrated cellular process that occurs in physiological and pathological conditions. It is also one of the most studied topics among cell biologists. An understanding of the underlying mechanism of apoptosis is important as it plays a pivotal role in the pathogenesis of many diseases. In some, the problem is due to too much apoptosis, such as in the case of degenerative diseases while in others, too little apoptosis is the culprit. Cancer is one of the scenarios where too little apoptosis occurs, resulting in malignant cells that will not die. The mechanism of apoptosis is complex and involves many pathways. Defects can occur at any point along these pathways, leading to malignant transformation of the affected cells, tumour metastasis and resistance to anticancer drugs. Despite being the cause of problem, apoptosis plays an important role in the treatment of cancer as it is a popular target of many treatment strategies. The abundance of literature suggests that targeting apoptosis in cancer is feasible. However, many troubling questions arise with the use of new drugs or treatment strategies that are designed to enhance apoptosis and critical tests must be passed before they can be used safely in human subjects
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