scholarly journals Influence of N-hydroxyurea on the growth of seedlings and the process of crown-gall tumour formation on sunflower plants

2015 ◽  
Vol 47 (1–2) ◽  
pp. 51-63 ◽  
Author(s):  
Aldona Rennert
Keyword(s):  
Direct Action ◽  
Transformation Process ◽  
Host Cells ◽  
Test Plant ◽  
Induction Phase ◽  
Experimental Conditions ◽  
Tumour Formation ◽  
Activity Curve ◽  
Crown Gall Tumour ◽  
Growth Of Seedlings

Hydroxyurea (HU) strongly inhibits formation of tumours induced with <i>Agrobacterium tumefaciens</i> in sunflower stems. This effect may partly be ascribed to the direct action of this substance on the bacterium. The course of the HU activity curve in the transformation process leads, however, to the supposition that it acts mainly on the host cells at the time corresponding to the induction phase. Maximal plant cell susceptibility to HU coincides with the wave of DNA synthesis induced by injury to the plant. Under the experimental conditions the time of HU activity in the tissues of the control test plant was limited, and the effects receded during its growth and development.

scholarly journals Phases of crown-gall transformation susceptible to hydroxyurea

2014 ◽  
Vol 53 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Aldona Rennert ◽  
Józef Kowalczyk ◽  
Halina Pajkowska
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Crown Gall ◽  
Pathogenic Bacteria ◽  
Direct Action ◽  
Plant Cells ◽  
Induction Phase ◽  
Bacterial Strains ◽  
Tumour Formation ◽  
Kalanchoë Daigremontiana ◽  
Anti Tumour Effect

With the use of bacterial strains, both sensitive and resistant to hydroxyurea the action of this inhibitor on tumour formation on the leaves of <em>Kalanchoe daigremontiana</em> infected with <em>Agrobacterium tumefaciens</em> was tested for five days after inoculation. The results are in agreement with the opinion that the anti-tumour effect of hydroxyurea applied in the induction phase (between 18 and 60 h after inoculation) is the result of its direct action on plant cells, whereas inhibition of tumour formation by the inhibitor in the inoculation period depends on its action on the pathogenic bacteria.

scholarly journals 1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1053
Author(s):  
Lidia Węglińska ◽  
Adrian Bekier ◽  
Katarzyna Dzitko ◽  
Barbara Pacholczyk-Sienicka ◽  
Łukasz Albrecht ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Direct Action ◽  
Human Fibroblasts ◽  
Imidazole Ring ◽  
Host Cells ◽  
In Vitro Assays ◽  
Host Cell Invasion

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b–12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b–12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

Co-Creation and social transformation: a tough issue for research

2020 ◽  
pp. 189-206
Author(s):  
Jim Segers
Keyword(s):  
Decision Making ◽  
Civil Society ◽  
Creative Process ◽  
Social Transformation ◽  
Direct Action ◽  
Transformation Process ◽  
Research Institutions ◽  
Research Methodologies ◽  
The Right

This chapter looks at social transformation through the lens of ‘tough issues’. The perspective makes the vast challenges communities are faced with more practical, which in turns allows for progress in the right direction through small wins. Many citizen and community organisations with a background in environmental, peace and third world movements have roots in direct action. Over recent decades, they have been moving from opposing developments to proposing alternatives. We use the words of de Certeau (1984) to describe it as a shift from ‘résistance’ to ‘bricolage’. This shift has brought them closer to more institutionalised partners like government, business, civil society and research institutions. While this rapprochement has proven beneficial to each party involved – research methodologies such as Co-Creation prove that notions like horizontal decision-making, anti-authoritarianism and self-organisation are no longer the preoccupation of informal actors solely – the different stakeholders have not become interchangeable. The chapter argues for the role of a third actor in a social transformation process. This actor is not a stakeholder itself, but through a creative process (“prototyping” in the case of City Mine(d), arts creation in others) becomes tactically linked to the important stakeholders.

A novel mechanism of olanzapine-induced lipid accumulation

2011 ◽  
Vol 26 (S2) ◽  
pp. 906-906 ◽  
Author(s):  
S. Dzitoyeva ◽  
H. Chen ◽  
R. Manev ◽  
H. Manev
Keyword(s):  
Lipid Content ◽  
Direct Action ◽  
Inhibitory Effect ◽  
Experimental Conditions ◽  
Cell Content ◽  
Metabolic Alterations ◽  
Low Concentrations ◽  
Mrna Content ◽  
Quantitative Western Blot

IntroductionSecond generation antipsychotic drugs (SGADs) including olanzapine trigger adverse metabolic alterations possibly by a direct action on adipocytes.Objectives and aimsThe system of the inflammatory 5-lipoxygenase (5-LOX) and its activating protein (FLAP) have been implicated in lipid dysfunction in obesity. We investigated whether this system could participate in the adipogenic action of olanzapine.MethodsExperiments were performed in 3T3-L1 adipocytes in vitro. Cells were treated with olanzapine and a FLAP inhibitor MK-886. Their lipid content, 5-LOX and FLAP mRNA content, and FLAP protein content were measured.ResultsOlanzapine treatment did not affect the cell content of 5-LOX mRNA; however, it decreased FLAP mRNA content at day five but not 24 hours after olanzapine addition. The inhibitory effect of olanzapine on FLAP expression was confirmed by quantitative Western blot assays. In the absence of a FLAP inhibitor, low concentrations of olanzapine (0.5 and 5 μM) increased lipid content only by about 13% (compared to about a 56% increase induced by 50 μM olanzapine) whereas in the presence of MK-886 these concentrations of olanzapine produced lipid increases comparable to the increase caused by 50 μM. In these experimental conditions, MK-886 alone did not alter the cell content of lipids.Conclusions5-LOX system may be involved in lipid dysfunction not only in conditions of obesity but possibly in SGAD-related metabolic alterations. The known polymorphism in the genes of the human 5-LOX system could play a role in setting a variable individual susceptibility to the metabolic side effects of SGADs.

scholarly journals THE INFECTION BY PLASMODIUM LOPHURAE OF DUCK ERYTHROCYTES IN THE CHICKEN EMBRYO

1953 ◽  
Vol 97 (6) ◽  
pp. 773-782 ◽  
Author(s):  
R. Barclay McGhee
Keyword(s):  
Death Rate ◽  
Total Cell ◽  
Host Cells ◽  
Chick Embryos ◽  
Experimental Conditions ◽  
Cell Numbers ◽  
Plasmodium Lophurae ◽  
Constant Rate ◽  
Morphological Differences ◽  
Rate Of Invasion

Certain morphological differences render it possible to recognize duck erythrocytes after introduction into the circulating blood of chick embryos infected with P. lophurae. 4 hours afterward, considerable numbers of merozoites have entered duck erythrocytes, while the parasitemia of the chick itself remains essentially unchanged in degree. By estimating the numbers of potentially invading merozoites from blood films made at the time of introduction of duck cells, it was learned that a relatively constant rate of invasion into duck cells by merozoites was maintained. In counter-distinction there was an ever increasing merozoite death rate in embryos not receiving duck cells concurrent with the increase in numbers of parasites. After the injection into parasitized embryos of duck erythrocytes showing but few parasites, no difference was apparent in the rate of merozoite invasion into the introduced cells and the host cells, respectively; but when the percentage of duck cells was greater, the rate of merozoite penetration diminished to zero. The selective penetration of duck erythrocytes which, under the experimental conditions obtaining, constituted only 30 per cent of the total cell numbers of most, and the inability of the merozoites to move independently, taken together, suggest that the greater susceptibility of the duck erythrocyte may be due to greater numbers of accessible areas on its surface. The decreased susceptibility following parasitization indicates that the presence of the parasite alters the cell in such wise that entry of additional parasites is rendered more difficult.

The role of amylin in the control of energy homeostasis

2010 ◽  
Vol 298 (6) ◽  
pp. R1475-R1484 ◽  
Author(s):  
Thomas A. Lutz
Keyword(s):  
Energy Homeostasis ◽  
Area Postrema ◽  
Body Weight Gain ◽  
Direct Action ◽  
Central Administration ◽  
Experimental Conditions ◽  
Hypothalamic Area ◽  
Chronic Infusion ◽  
The Brain

Amylin is an important player in the control of nutrient fluxes. Amylin reduces eating via a meal size effect by promoting meal-ending satiation. This effect seems to depend on a direct action in the area postrema (AP), which is an area rich in amylin receptors. Subsequent to the activation of AP neurons, the neural signal is conveyed to the forebrain via relays involving the nucleus of the solitary tract (NTS) and the lateral parabrachial nucleus (lPBN) to the lateral hypothalamic area (LHA) and other hypothalamic nuclei. While the NTS and lPBN seem to be necessary for amylin's eating inhibitory effect, the role of the LHA has not yet been fully investigated. Amylin may also act as an adiposity signal. Plasma levels of amylin are higher in obese individuals, and chronic infusion of amylin into the brain reduces body weight gain and adiposity; chronic infusion of an amylin receptor antagonist into the brain increases body adiposity. Amylin increases energy expenditure in rats; this effect occurs under various experimental conditions after peripheral and central administration. Together, these animal data, but also clinical data in humans, indicate that amylin is a promising candidate for the treatment of obesity; effects are most pronounced when amylin is combined with leptin. Finally, recent findings indicate that amylin acts as a neurotrophic factor in specific brain stem areas. Whether this effect may be relevant under physiological conditions requires further studies.

scholarly journals Effect of Host Cells on Low- and Medium-Pressure UV Inactivation of Adenoviruses

2010 ◽  
Vol 76 (21) ◽  
pp. 7068-7075 ◽  
Author(s):  
Huiling Guo ◽  
Xiaona Chu ◽  
Jiangyong Hu
Keyword(s):  
Host Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Host Cells ◽  
Uv Disinfection ◽  
Human Embryonic Kidney ◽  
Experimental Conditions ◽  
Medium Pressure ◽  
Serotype 5 ◽  
Uv Dose

ABSTRACT UV disinfection is highly effective against most pathogens, with the exception of the adenoviruses (AD). To date, many studies have focused on low-pressure (LP) UV inactivation of AD, but little is known about the effect of medium-pressure (MP) UV inactivation of AD. Despite numerous studies of LP UV inactivation of AD, extreme variabilities in the LP UV dose requirements of AD had been observed because of differing experimental conditions used, such as the types of cell lines used for AD enumeration. This study therefore investigates the effect of three different host cell lines (PLC/PRF/5, human embryonic kidney 293 [HEK293], and XP17BE) on the LP and MP UV dose requirements of AD serotype 5 (AD5), AD40, and AD41 under similar experimental settings. Results showed that for 4-log inactivation of AD, LP UV and MP UV doses needed to be in the ranges of 123 to 182 mJ/cm2 and 65 to 90 mJ/cm2, respectively, when HEK293 and PLC/PRF/5 cells were used for enumeration. The UV doses required for MP UV inactivation of AD were significantly lower than those required for LP UV inactivation (P value < 0.05). When different cell lines were used for enumeration, UV dose requirements for AD differed. AD were portrayed to be most susceptible to UV (LP UV doses of <57 mJ/cm2 and MP UV doses of <42 mJ/cm2 for 4-log AD inactivation) when the XP17BE cells were used as the host cell. The use of different cell lines for AD enumeration affected LP UV dose results more significantly than MP UV dose results (P value < 0.05). Cell line variability factors for LP UV disinfection (CLLP) and MP UV disinfection (CLMP) for AD5, AD40, and AD41 enumerated with HEK293, PLC/PRF/5, and XP17BE cells were in the ranges of 1.0 to 3.2 and 1.0 to 2.5, respectively.

scholarly journals Nematode-Induced Endoreduplication in Plant Host Cells: Why and How?

2013 ◽  
Vol 26 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Janice de Almeida Engler ◽  
Godelieve Gheysen
Keyword(s):  
Cell Cycle ◽  
Current Knowledge ◽  
Giant Cells ◽  
Transformation Process ◽  
Host Cells ◽  
Cyst Nematodes ◽  
Plant Host ◽  
Root Cells ◽  
Cell Cycles ◽  
Feeding Sites

Plant-parasitic root-knot and cyst nematodes have acquired the ability to induce remarkable changes in host cells during the formation of feeding sites. Root-knot nematodes induce several multinucleate giant cells inside a gall whereas cyst nematodes provoke the formation of a multinucleate syncytium. Both strategies impinge on the deregulation of the cell cycle, involving a major role for endoreduplication. This review will first describe the current knowledge on the control of normal and aberrant cell cycles. Thereafter, we will focus on the role of both cell-cycle routes in the transformation process of root cells into large and highly differentiated feeding sites as induced by the phytoparasitic root-knot and cyst nematodes.

ANTIGOITROGENIC EFFECT OF CASEIN

1976 ◽  
Vol 83 (4) ◽  
pp. 763-771 ◽  
Author(s):  
Eduardo Gaitán ◽  
Héctor Merino
Keyword(s):  
Direct Action ◽  
Free Water ◽  
Iodine Intake ◽  
Dietary Factors ◽  
Albino Rats ◽  
Experimental Conditions ◽  
Thyroid Glands ◽  
Special Diets ◽  
Antithyroid Agents ◽  
Protein Free Diet

ABSTRACT Epidemiological findings from the city of Cali, Colombia, support the hypothesis that water supply and iodine intake are not the only dietary factors which influence the magnitude of the goitre endemia. Experiments were conducted in rats to determine whether casein has a counteracting effect on the goitrogenic and antithyroid activities of methimazole (MMI) and goitrogenic water extracts (GWE) from the endemic area of the Cauca Valley. Female albino rats (Charles River, DC strain) 100–110 g initial weight, receiving 12 μg of iodine daily, were divided into three groups and put on special diets: protein-free, 8% casein, or 60% casein, respectively. Each group (24 rats) was then divided into three subgroups. Subgroup one received goitrogen-free water and was used as a control. Subgroup two was administered MMI, 50 μg/day/rat. Subgroup three was given per animal a daily amount of GWE equivalent in antithyroid potency to 50 μg of MMI. At 77 days, the thyroid glands were studied for weight, 131I uptake, and 127I concentration. Animals on the protein-free diet showed significantly (P < 0.05 – < 0.01) larger thyroid glands per 100 g body weight and lower thyroidal 4 h 131I uptake and 127I-concentrations than rats on casein diets. These differences were significantly increased (P < 0.01) by the administration of MMI and GWE. All the effects were completely reversed by the 60 % casein diet showing no differences between control rats and those on MMI or GWE. Rats on 8 % casein showed intermediate values between those of animals on protein-free and 60% casein diets; differences were still present between the control as against the MMI or GWE groups. The results indicate that under these experimental conditions, a poor-protein diet impairs the thyroidal transport of iodine, decreases its concentration in the thyroid and is accompanied by an enlargement of the gland. Under these circumstances, the action of thiourea-like antithyroid agents is enhanced. The administration of protein reverses these alterations and decreases the action of such antithyroid agents. Whether the changes observed are due to a direct action of casein on the thyroid and/or to effects of malnutrition on the metabolism of antithyroid compounds remains to be determined.

scholarly journals Avian [beta]-defensins as antimicrobial and immunomodulatory agents

2018 ◽  
Author(s):  
◽  
Ming Yang
Keyword(s):  
Dendritic Cells ◽  
Antimicrobial Peptides ◽  
Animal Health ◽  
Host Cells ◽  
Manufacturing Cost ◽  
Experimental Conditions ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Immature Dendritic Cells ◽  
Beta Defensins

The increasing prevalence of antibiotic-resistance and lack of effective antibiotics pose a serious threat to animal health and public health. Host antimicrobial peptides (AMPs) show broad-spectrum antimicrobial activity against various microbes with low potential for resistance development, compared to conventional antibiotics, indicating great potentials as therapeutic agents. Despite such promise, several limitations hinder the application of AMPs in the clinic, including high manufacturing cost, cytotoxicity, and stability in physiological conditions. New strategies are needed to solve those problems for their application. Avian beta-defensins (AvBD) are small, cationic, antimicrobial peptides. The potential application of AvBDs as antibiotic alternatives against antibiotic-resistant and zoonotic bacterial pathogens has been the subject of interest. In the first study, the biological functions of two AvBDs, AvBD-6 and AvBD-12, were determined under various experimental conditions. The results showed that AvBD-6 (+7) was more potent than AvBD-12 (+1) against E. coli, S. Typhimurium, and S. aureus as well as clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae. The antibacterial activity of AvBDs was greatly compromised under physiological salt concentrations. Both AvBDs demonstrated mild chemotactic property for chicken macrophages and AvBD-12, at relatively high concentrations, could also induce the migration of murine immature dendritic cells. The chemotactic property required the presence of chemokine receptor 2 (CCR2) on host cells and the conserved disulfide bridges of the peptides. The two AvBDs were nontoxic to CHO-K1, macrophages, or immature dendritic cells.

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