scholarly journals Phloem Protein Partners of Cucurbit aphid borne yellows virus: Possible Involvement of Phloem Proteins in Virus Transmission by Aphids

2010 ◽  
Vol 23 (6) ◽  
pp. 799-810 ◽  
Author(s):  
B. Bencharki ◽  
S. Boissinot ◽  
S. Revollon ◽  
V. Ziegler-Graff ◽  
M. Erdinger ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Virus Transmission ◽  
Aphid Transmission ◽  
High Concentration ◽  
Viral Genomes ◽  
Protein Partners ◽  
Sieve Tubes ◽  
Phloem Feeding

Poleroviruses are phytoviruses strictly transmitted by phloem-feeding aphids in a circulative and nonpropagative mode. During ingestion, aphids sample virions in sieve tubes along with sap. Therefore, any sap protein bound to virions will be acquired by the insects and could potentially be involved in the transmission process. By developing in vitro virus-overlay assays on sap proteins collected from cucumber, we observed that approximately 20 proteins were able to bind to purified particles of Cucurbit aphid borne yellows virus (CABYV). Among them, eight proteins were identified by mass spectrometry. The role of two candidates belonging to the PP2-like family (predominant lectins found in cucurbit sap) in aphid transmission was further pursued by using purified orthologous PP2 proteins from Arabidopsis. Addition of these proteins to the virus suspension in the aphid artificial diet greatly increased virus transmission rate. This shift was correlated with an increase in the number of viral genomes in insect cells and with an increase of virion stability in vitro. Surprisingly, increase of the virus transmission rate was also monitored after addition of unrelated proteins in the aphid diet, suggesting that any soluble protein at sufficiently high concentration in the diet and acquired together with virions could stimulate virus transmission.

scholarly journals The Role of Vitamin C in Cancer Prevention and Therapy: A Literature Review

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1894
Author(s):  
Marcelo Villagran ◽  
Jorge Ferreira ◽  
Miquel Martorell ◽  
Lorena Mardones
Keyword(s):  
Clinical Trials ◽  
Vitamin C ◽  
Cancer Prevention ◽  
Randomized Study ◽  
Regulation Of Gene Expression ◽  
Water Soluble ◽  
In Vitro Assays ◽  
High Concentration

Vitamin C is a water-soluble antioxidant associated with the prevention of the common cold and is also a cofactor of hydrolases that participate in the synthesis of collagen and catecholamines, and in the regulation of gene expression. In cancer, vitamin C is associated with prevention, progression, and treatment, due to its general properties or its role as a pro-oxidant at high concentration. This review explores the role of vitamin C in cancer clinical trials and the aspects to consider in future studies, such as plasmatic vitamin C and metabolite excretion recording, and metabolism and transport of vitamin C into cancer cells. The reviewed studies show that vitamin C intake from natural sources can prevent the development of pulmonary and breast cancer, and that vitamin C synergizes with gemcitabine and erlotinib in pancreatic cancer. In vitro assays reveal that vitamin C synergizes with DNA-methyl transferase inhibitors. However, vitamin C was not associated with cancer prevention in a Mendelian randomized study. In conclusion, the role of vitamin C in the prevention and treatment of cancer is still an ongoing area of research. It is necessary that new phase II and III clinical trials be performed to collect stronger evidence of the therapeutic role of vitamin C in cancer.

Role of calcium and calmodulin in release of kallikrein and tonin from rat submandibular gland

1986 ◽  
Vol 250 (3) ◽  
pp. C480-C485 ◽  
Author(s):  
S. R. Maitra ◽  
O. A. Carretero ◽  
S. W. Smith ◽  
S. F. Rabito
Keyword(s):  
Submandibular Gland ◽  
Incubation Medium ◽  
High Concentration ◽  
Calcium Blockers ◽  
Control Value ◽  
Voltage Dependent ◽  
Voltage Dependent Calcium Channels ◽  
Intracellular Mediators

We investigated the role of calcium and calmodulin as intracellular mediators of kallikrein and tonin release induced by norepinephrine (NE). We studied the secretion rate of kallikrein and tonin from submandibular gland of rat in response to NE in the presence or absence of calcium, two calcium blockers, and four different calmodulin antagonists. Submandibular gland slices were incubated in vitro, and glandular kallikrein and tonin secreted into the incubation medium were determined by direct radioimmunoassays and expressed as nanograms per minute per milligram tissue. NE (10(-5) and 10(-4) M) increased the kallikrein secretion from the control value of 8.2 +/- 2.6 to 134.9 +/- 41.4 (P less than 0.05) and to 191.2 +/- 62.7 (P less than 0.05), and the release of tonin from a basal rate of 3.5 +/- 0.6 to 51.5 +/- 9.1 (P less than 0.05) and to 64.4 +/- 13.7 (P less than 0.05). The deletion of calcium and addition of EGTA into the incubation medium significantly attenuated the secretion of kallikrein and tonin induced by NE. Nifedipine, at concentrations which inhibit voltage-dependent calcium channels, did not affect the release of kallikrein and tonin, and only a high concentration (10(-4) M) reduced the release. TMB-8, a blocker of intracellular calcium, had no effect either. Phenothiazines, triflupromazine (10(-6) M) and trifluoperazine (10(-4) M), decreased significantly the kallikrein release elicited by 10(-5) M NE.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Saprophytic Activity and Sporulation of Cryphonectria parasitica on Dead Chestnut Wood in Forests with Naturally Established Hypovirulence

2006 ◽  
Vol 96 (12) ◽  
pp. 1337-1344 ◽  
Author(s):  
S. Prospero ◽  
M. Conedera ◽  
U. Heiniger ◽  
D. Rigling
Keyword(s):  
Biological Control ◽  
Dead Wood ◽  
Transmission Rate ◽  
Virus Transmission ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
The Mean ◽  
Chestnut Wood

Sustainable biological control of the chestnut blight fungus Crypho-nectria parasitica with hypovirulence depends on the production and dissemination of hypovirus-infected propagules of the pathogen. We investigated the ability of C. parasitica to sporulate and produce hypo-virus-infected spores on recently dead chestnut wood in coppice stands in southern Switzerland where hypovirulence has been naturally established. The number and type (active, inactive, or none) of cankers was assessed on experimentally cut and stacked stems, firewood stacks, and natural dead wood. Hypovirus-free and hypovirus-infected strains readily survived for more than 1 year in the chestnut blight cankers of the stacked stems. Sporulation of C. parasitica was observed on the surface of preexisting inactive and active cankers, as well as on newly colonized bark areas and was significantly more abundant than on comparable cankers on living stems. On all types of dead wood, we observed more stromata with perithecia than with pycnidia; however, a large proportion of the stromata was not differentiated. All perithecia examined yielded only hypovirus-free ascospores. The incidence of pycnidia that produced hypovirus-infected conidia ranged from 5% on natural dead wood to 41% on the experimental stacks. The mean virus transmission rate into conidia was 69%. Our study demonstrates a considerable saprophytic activity of C. parasitica on recently dead chestnut wood and supports the hypothesis of a role of this saprophytic phase in the epidemiology of hypovirulence.

scholarly journals Current aspects of pharmacologic application of bile acids

2003 ◽  
Vol 56 (5-6) ◽  
pp. 237-242 ◽  
Author(s):  
Momir Mikov ◽  
Ksenija Kuhajda ◽  
Julijan Kandrac
Keyword(s):  
Bile Acids ◽  
Virus Transmission ◽  
Therapeutic Agents ◽  
Current Therapy ◽  
Therapeutic Application ◽  
Pharmacological Studies ◽  
Other Substances ◽  
Anti Hiv

Effects of bile acids and their salts on absorption of other substances Bile acids and their salts increase intestinal absorption of lipids and transmembrane and paracellular transfer of small and endogenous and exogenous polar molecules. It has been established that they are good promotores of insulin absorption through skin and nasal mucose, and of blood-brain barrier transfer of salycilates and quinine. Effects of bile acids and their salts on absorption of other substances and their potential action It has been established that combination of bile acids with amphotericin B has potential Leishmanicideal effect and combination with ciprofloxacine has improved its antibacterial activity against Pseudomonas aeruginosa in vitro. Bile acids pharmacodynamic effects Bile acids have analgesic and hypoglycemic effect They also have anti-HIV effect probably suppressing virus transmission from cell to cell. Conclusion New studies of natural bile acids and new synthetic bile acids have revealed that they are not only adjuvants to existing active principles in pharmaceutical forms, but they can act as new therapeutic agents. However, it is necessary to study their possible mechanisms, but they are not crucial for their therapeutic application. Toxicological and pharmacological studies will determine the role of newly synthetized bile acids and their salts in current therapy.

Release of galanin from isolated perfused porcine adrenal glands: role of splanchnic nerves

1991 ◽  
Vol 261 (1) ◽  
pp. E31-E40 ◽  
Author(s):  
J. J. Holst ◽  
M. Ehrhart-Bornstein ◽  
T. Messell ◽  
S. S. Poulsen ◽  
H. Harling
Keyword(s):  
Nerve Stimulation ◽  
Adrenal Glands ◽  
Splanchnic Nerve ◽  
High Concentration ◽  
Vitro Model ◽  
Arterial Plasma ◽  
Regulatory Functions ◽  
Splanchnic Nerve Stimulation

We found a high concentration of galanin in extracts of porcine adrenal glands (114 pmol/g). By immunohistochemistry, galanin was localized to groups of medullary cells previously shown to produce norepinephrine. To study mechanisms for the release of galanin, we developed the following in vitro model: isolated perfused porcine adrenals with intact splanchnic nerve supply. When the nerves were electrically stimulated, epinephrine and norepinephrine secretion increased 276- and 291-fold, respectively, and galanin release increased up to 1,300-fold. Acetylcholine at 10(-6) M stimulated galanin release, and hexamethonium almost abolished the response to nerve stimulation. Galanin infusions had no effect on epinephrine and norepinephrine secretion in concentrations of 10(-8) and 10(-7) M, but increased both cortisol and aldosterone secretion (P less than 0.05). Splanchnic nerve stimulation in anesthetized pigs increased the concentration of galanin in the caval vein but not in arterial plasma. It is concluded that galanin, coreleased with catecholamines from the adrenal glands, may have endocrine functions but that galanin may also have local regulatory functions in the adrenals.

Detection of the Na(+)-K(+)-ATPase alpha 3-isoform in multinucleated macrophages

1991 ◽  
Vol 260 (5) ◽  
pp. F704-F709 ◽  
Author(s):  
A. Vignery ◽  
F. Wang ◽  
H. Y. Qian ◽  
E. J. Benz ◽  
M. Gilmore-Hebert
Keyword(s):  
Regulation Of Gene Expression ◽  
Giant Cells ◽  
Alpha Subunit ◽  
Specific Function ◽  
High Concentration ◽  
Subunit Mrna ◽  
Novel Model

We previously reported that multinucleated macrophages express a high concentration of Na(+)-K(+)-ATPases that are concentrated on the nonadherent domain of their plasma membrane (A. Vignery, T. Niven-Fairchild, D. H. Ingbar, and M. Caplan. J. Histochem. Cytochem. 37: 1265-1271, 1989). We also showed that an increase in newly synthesized alpha-subunit occurred during cell culture and multinucleation. We now present evidence that macrophage multinucleation in vitro is accompanied by an increased accumulation of Na(+)-K(+)-ATPase alpha-subunit mRNA. Most interesting is the detection of significant amount of both alpha 1- and alpha 3-isoform mRNA and peptide in these cells by in situ hybridization, Northern and Western blot analyses. These qualitative and quantitative variations in Na(+)-K(+)-ATPase expression suggest that macrophage multinucleation is accompanied by a coordinated regulation of gene expression and that multinucleation confers a specific function to macrophages. Multinucleated macrophages offer a novel model system to investigate not only the specific function(s) of the alpha 3-isoform but also the role of the Na(+)-K(+)-ATPase in giant cells and osteoclasts.

scholarly journals Impacts of Social and Economic Factors on the Transmission of Coronavirus Disease 2019 (COVID-19) in China

2020 ◽  
Author(s):  
Yun Qiu ◽  
Xi Chen ◽  
Wei Shi
Keyword(s):  
Socioeconomic Factors ◽  
Transmission Rate ◽  
Virus Transmission ◽  
The Novel ◽  
Virus Spread ◽  
Government Response ◽  
Machine Learning Approach ◽  
The Rich ◽  
Novel Coronavirus

AbstractThis paper examines the role of various socioeconomic factors in mediating the local and cross-city transmissions of the novel coronavirus 2019 (COVID-19) in China. We implement a machine learning approach to select instrumental variables that strongly predict virus transmission among the rich exogenous weather characteristics. Our 2SLS estimates show that the stringent quarantine, massive lockdown and other public health measures imposed in late January significantly reduced the transmission rate of COVID-19. By early February, the virus spread had been contained. While many socioeconomic factors mediate the virus spread, a robust government response since late January played a determinant role in the containment of the virus. We also demonstrate that the actual population flow from the outbreak source poses a higher risk to the destination than other factors such as geographic proximity and similarity in economic conditions. The results have rich implications for ongoing global efforts in containment of COVID-19.

scholarly journals Febrile temperatures increase in vitro antibody affinity for malaria and dengue antigens

2018 ◽  
Author(s):  
Razvan C. Stan ◽  
Katia S. Françoso ◽  
Rubens P.S. Alves ◽  
Luís Carlos S. Ferreira ◽  
Irene S. Soares ◽  
...  
Keyword(s):  
Immune Responses ◽  
Binding Affinity ◽  
The Body ◽  
Antibody Affinity ◽  
Positive Role ◽  
Protein Partners ◽  
Adaptive Role

AbstractFever is a regulated elevation in the body setpoint temperature and may arise as a result of infectious and noninfectious causes. While beneficial in modulating immune responses to infection, the potential of febrile temperatures in regulating antigen binding affinity to antibodies has not been explored. We have investigated this process under in vitro conditions using selected malaria or dengue antigens and specific monoclonal antibodies, and observed a marked increase in the affinity of these antibody-antigen complexes at 40°C, compared to physiological (37°C) or pathophysiological temperatures (42°C). Induced thermal equilibration of the protein partners at these temperatures, prior to measurements, further increased their binding affinity. These results may indicate an unexpected beneficial and adaptive role for fever in vivo, and highlight the positive role of thermal priming in enhancing protein-protein affinity for samples of scarce availability.

scholarly journals How does the NPM1 mutant induce leukemia?

2011 ◽  
Vol 3 (2s) ◽  
pp. 6 ◽  
Author(s):  
Paolo Sportoletti
Keyword(s):  
Myeloid Leukemia ◽  
Tumor Development ◽  
Genetic Alterations ◽  
In Vivo Studies ◽  
Npm1 Mutation ◽  
Protein Partners ◽  
Cellular Pathways

NPM1 is the most frequently mutated gene in AML and the role of the NPM1 mutant in acute myeloid leukemia along with its leukemogenic potential are still under investigation. NPM1 genetic alterations can contribute to leukemogenesis through the direct oncogenic effect of the mutant protein and the concomitant loss of one functional allele. Npm1 loss determines tumor development in the mouse while in human NPM1 maps in a chromosomal region frequently loss in myelodysplastic syndrome (MDS). The NPM1 mutant cytoplasmic delocalization in leukemic blasts alters multiple cellular pathways through either loss or gain of function effects on different protein partners. Here we discuss the most relevant studies on the role of the NPM1 molecule in hematological malignancies and both in vitro and in vivo studies that are trying to elucidate the way by which the NPM1 mutation induces leukemia.

scholarly journals ANTIBODY PRODUCTION IN VITRO

1968 ◽  
Vol 127 (4) ◽  
pp. 675-691 ◽  
Author(s):  
Gilmour Harris
Keyword(s):  
Immune Response ◽  
Antibody Production ◽  
Actinomycin D ◽  
Recovery Effect ◽  
High Concentration ◽  
Isolated Cells ◽  
Antibody Synthesis ◽  
Specific Antigens

The effects of actinomycin D and puromycin on spleen cell suspensions from rabbits immunized to SRC's were studied. These inhibitors, in high concentration, suppressed PFC's when added initially to recently isolated cells. When such cells were incubated for several days in the presence of both antigen and inhibitor, both actinomycin D and puromycin produced an increase in PFC's after the initial suppression. This recovery effect was best seen with cells from rabbits killed 3 days after boosting with SRC's, and was usually absent when cells were taken from rabbits killed 2 days after boosting. When actinomycin D or puromycin was added after several days in culture in the presence of SRC's, surviving PFC's were found to be not only resistant to these inhibitors, but there was also an increased number of PFC's compared to similar cultures incubated without these agents. Radioautographic studies showed that PFC's stimulated by the presence of actinomycin D or puromycin were not incorporating precursors for RNA or protein synthesis. In view of the known mode of action of these inhibitors, it was postulated that they were stimulating antibody production by PFC's in vitro either by interfering with represser mechanisms or stimulating the completion of antibody molecules, perhaps by causing the release of preformed antibody chains from ribosomes. Since the presence of specific antigens in vitro were necessary for these observed stimulatory effects on PFC's, and since antigens were producing an effect on antibody production on cells which were being suppressed by these inhibitors, added initially, it was further suggested that one role of antigen in the immune response was concerned with the completion of antibody synthesis on the ribosomes, perhaps by acting as an inducer as has been suggested previously (1).

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