scholarly journals Virulence parameters in the characterization of strains of Entamoeba histolytica

1997 ◽  
Vol 39 (2) ◽  
pp. 65-70 ◽  
Author(s):  
Maria A GOMES ◽  
Maria N. MELO ◽  
Gil P.M. PENA ◽  
Edward F. SILVA
Keyword(s):  
Entamoeba Histolytica ◽  
Cytopathic Effect ◽  
Axenic Culture ◽  
Vero Cells ◽  
In Vitro Assays ◽  
Biological Assays ◽  
Restriction Fragment Pattern

Differences in virulence of strains of Entamoeba histolytica have long been detected by various experimental assays, both in vivo and in vitro. Discrepancies in the strains characterization have been arisen when different biological assays are compared. In order to evaluate different parameters of virulence in the strains characterization, five strains of E. histolytica, kept under axenic culture, were characterized in respect to their, capability to induce hamster liver abscess, erythrophagocytosis rate and cytopathic effect upon VERO cells. It was found significant correlation between in vitro biological assays, but not between in vivo and in vitro assays. Good correlation was found between cytopathic effect and the mean number of uptaken erythrocytes, but not with percentage of phagocytic amoebae, showing that great variability can be observed in the same assay, according to the variable chosen. It was not possible to correlate isoenzyme and restriction fragment pattern with virulence indexes since all studied strains presented pathogenic patterns. The discordant results observed in different virulence assays suggests that virulence itself may not the directly assessed. What is in fact assessed are different biological characteristics or functions of the parasite more than virulence itself. These characteristics or functions may be related or not with pathogenic mechanisms occurring in the development of invasive amoebic disease

scholarly journals Functional Characterization of the mazEF Toxin-Antitoxin System in the Pathogenic Bacterium Agrobacterium tumefaciens

2021 ◽  
Vol 9 (5) ◽  
pp. 1107
Author(s):  
Wonho Choi ◽  
Yoshihiro Yamaguchi ◽  
Ji-Young Park ◽  
Sang-Hyun Park ◽  
Hyeok-Won Lee ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Physiological Function ◽  
Functional Characterization ◽  
Site Directed Mutagenesis ◽  
In Vitro Assays ◽  
Cell Growth Inhibition ◽  
The Right

Agrobacterium tumefaciens is a pathogen of various plants which transfers its own DNA (T-DNA) to the host plants. It is used for producing genetically modified plants with this ability. To control T-DNA transfer to the right place, toxin-antitoxin (TA) systems of A. tumefaciens were used to control the target site of transfer without any unintentional targeting. Here, we describe a toxin-antitoxin system, Atu0939 (mazE-at) and Atu0940 (mazF-at), in the chromosome of Agrobacterium tumefaciens. The toxin in the TA system has 33.3% identity and 45.5% similarity with MazF in Escherichia coli. The expression of MazF-at caused cell growth inhibition, while cells with MazF-at co-expressed with MazE-at grew normally. In vivo and in vitro assays revealed that MazF-at inhibited protein synthesis by decreasing the cellular mRNA stability. Moreover, the catalytic residue of MazF-at was determined to be the 24th glutamic acid using site-directed mutagenesis. From the results, we concluded that MazF-at is a type II toxin-antitoxin system and a ribosome-independent endoribonuclease. Here, we characterized a TA system in A. tumefaciens whose understanding might help to find its physiological function and to develop further applications.

scholarly journals Method combining BAC film and positive staining for the characterization of DNA intermediates by dark-field electron microscopy

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Yann Benureau ◽  
Eliana Moreira Tavares ◽  
Ali-Akbar Muhammad ◽  
Sonia Baconnais ◽  
Eric Le Cam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
In Vitro Assays ◽  
Positive Staining ◽  
Synthetic Dna ◽  
Dark Field Imaging ◽  
Alkyl Ammonium

Abstract DNA intermediate structures are formed in all major pathways of DNA metabolism. Transmission electron microscopy (TEM) is a tool of choice to study their choreography and has led to major advances in the understanding of these mechanisms, particularly those of homologous recombination (HR) and replication. In this article, we describe specific TEM procedures dedicated to the structural characterization of DNA intermediates formed during these processes. These particular DNA species contain single-stranded DNA regions and/or branched structures, which require controlling both the DNA molecules spreading and their staining for subsequent visualization using dark-field imaging mode. Combining BAC (benzyl dimethyl alkyl ammonium chloride) film hyperphase with positive staining and dark-field TEM allows characterizing synthetic DNA substrates, joint molecules formed during not only in vitro assays mimicking HR, but also in vivo DNA intermediates.

scholarly journals RBP-L, a transcription factor related to RBP-Jkappa.

1997 ◽  
Vol 17 (5) ◽  
pp. 2679-2687 ◽  
Author(s):  
S Minoguchi ◽  
Y Taniguchi ◽  
H Kato ◽  
T Okazaki ◽  
L J Strobl ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Notch Receptor ◽  
In Vitro Assays ◽  
Functional Interaction ◽  
Protein Protein Interaction ◽  
Isolation And Characterization ◽  
Signalling Molecule

RBP-Jkappa is a sequence-specific DNA binding protein which plays a central role in signalling downstream of the Notch receptor by physically interacting with its intracellular region. Although at least four Notch genes exist in mammals, it is unknown whether each Notch requires a specific downstream signalling molecule. Here we report isolation and characterization of a mouse RBP-Jkappa-related gene named RBP-L that is expressed almost exclusively in lung, in contrast to the ubiquitous expression of RBP-Jkappa. For simplicity, we propose to call RBP-Jkappa RBP-J. The RBP-L protein bound to a DNA sequence almost identical to that of RBP-J. Surprisingly, RBP-L did not interact with any of the known four mouse Notch proteins. Although we found that RBP-L and EBNA-2 cooperated in transcriptional activation, they did not show significantly strong protein-protein interaction that can be detected by several in vivo and in vitro assays. This is again in contrast to physical association of RBP-J with EBNA-2. Several models to explain functional interaction between RBP-L and EBNA-2 are discussed.

scholarly journals Use of in vivo and in vitro assays for the characterization of mammalian excision repair and isolation of repair proteins

1990 ◽  
Vol 236 (2-3) ◽  
pp. 223-238 ◽  
Author(s):  
J.H.J. Hoeijmakers ◽  
A.P.M. Eker ◽  
R.D. Wood ◽  
P. Robins
Keyword(s):  
Excision Repair ◽  
In Vitro Assays

scholarly journals Persistence of SARS-CoV-2 infection on personal protective equipment (PPE)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Elizabeth Córdoba-Lanús ◽  
Omar García-Pérez ◽  
Sara Cazorla-Rivero ◽  
Francisco Rodríguez-Esparragón ◽  
José-Enrique Piñero ◽  
...  
Keyword(s):  
Personal Protective Equipment ◽  
Post Infection ◽  
Cytopathic Effect ◽  
Clinical Sample ◽  
Rna Stability ◽  
Vero Cells ◽  
In Vitro Assays ◽  
Protective Equipment ◽  
Viral Loads

Abstract Background SARS-CoV-2 stability and infection persistence has been studied on different surfaces, but scarce data exist related to personal protective equipment (PPE), moreover using realist viral loads for infection. Due to the importance for adequate PPE management to avoid risk of virus infection, RNA stability was evaluated on PPE. Methods Persistence of SARS-CoV-2 infection and detection of genomic RNA in PPE (gowns and face masks) were determined by in-vitro assays and RT-qPCR, respectively. Samples were infected with a clinical sample positive for SARS-CoV-2 (Clin-Inf), and with a heat-inactivated SARS-CoV-2 strain sample (Str-Inf) as a control. Results PPE samples infected with Clin-Inf were positive for the 3 viral genes on gowns up to 5 days post-infection, whereas these overall genes were detected up to 30 days in the case of face masks. However, gowns and FFP2 masks samples contaminated with Clin-Inf showed a cytopathic effect over VERO cells up to 5–7 days post-infection. Conclusions SARS-CoV-2 RNA was detected on different PPE materials for 5 to 30 days, but PPE contaminated with the virus was infectious up to 5–7 days. These findings demonstrate the need to improve PPE management and to formulate strategies to introduce viricidal compounds in PPE fabrics.

scholarly journals In vitro and in vivo Antiamoebic Potential of Actinopyga lecanora (Jaeger)

2015 ◽  
Vol 18 (2) ◽  
pp. 118-120 ◽  
Author(s):  
Vijai Lakshmi ◽  
Sheela Ghosal
Keyword(s):  
Entamoeba Histolytica ◽  
Symptomatic Relief ◽  
Pharmaceutical Journal ◽  
Climatic Conditions ◽  
Isolation And Characterization ◽  
Histolytica Infection ◽  
Antiamoebic Activity

Human amoebiasis, due to Entamoeba histolytica infection, is mainly associated with morbidity thus affecting the quality of life and pace of development in the countries with warm climatic conditions. So far, the available drugs provide only symptomatic relief and they are not devoid of side effects. This leads to obtain novel molecules from natural sources having antiamoebic activity. The methanol extract of Actinopyga lecanora (Jaeger) displayed antiamoebic activity. It showed MIC 125 ?g/ml in our in-vitro studies, but when it was tested in rats, it revealed 88% inhibition of trophozoites at the dose of 900 mg/kg body weight against Entamoeba histolytica. Further work is in progress for the isolation and characterization of active molecules.Bangladesh Pharmaceutical Journal 18(2): 118-120, 2015

scholarly journals Pharmacological characterization of repeated administration of the first generation abused synthetic cannabinoid CP47,497

2016 ◽  
Vol 27 (3) ◽  
Author(s):  
Travis W. Grim ◽  
Kimberly L. Samano ◽  
Bogna Ignatowska-Jankowska ◽  
Qing Tao ◽  
Laura J. Sim-Selly ◽  
...  
Keyword(s):  
G Proteins ◽  
First Generation ◽  
Repeated Administration ◽  
Synthetic Cannabinoid ◽  
In Vitro Assays ◽  
Pharmacological Effects ◽  
Pharmacological Characterization

AbstractA series of in vivo and in vitro assays were conducted to characterize the pharmacological effects of the first generation abused synthetic cannabinoid CP47,497, a racemic bicyclic cannabinoid that is similar in structure to the potent, high-efficacy synthetic cannabinoid CP55,940. CP47,497 was less efficacious than CP55,940 in activating G-proteins and dose-dependently produced common CB

scholarly journals The glycoprotein of measles virus. External radioactive labelling of its carbohydrate and partial characterization of the glycopeptide

1980 ◽  
Vol 185 (1) ◽  
pp. 189-194 ◽  
Author(s):  
O Anttonen ◽  
M Jokinen ◽  
A Salmi ◽  
R Vainionpää ◽  
C G Gahmberg
Keyword(s):  
Sialic Acid ◽  
Measles Virus ◽  
Vero Cells ◽  
Galactose Oxidase ◽  
Culture Supernatants ◽  
Surface Carbohydrates ◽  
Specific Labelling

Measles virus was propagated in VERO cells and purified from the culture supernatants by two successive tartrate-density-gradient centrifugations. Surface carbohydrates were labelled both in vitro and in vivo with 3H after treatment with galactose oxidase/NaB3H4 or with [3H]glucosamine. The major labelled glycoprotein in measles virions had a mol.wt. of 79 000. After labelling with periodate/NaB3H4, which would result in specific labelling of sialic acid residues, the 79 000-mol.wt. glycoprotein was very weakly labelled. This suggests that there is no or a very low amount of sialic acid in the virions. Further analysis of the glycoprotein showed that galactose is the terminal carbohydrate unit in the oligosaccharide, and the molecular weight of the glycopeptide obtained after Pronase digestion is about 3000. The oligosaccharide is attached to the polypeptide through an alkali-stable bond, indicating a N-glycosidic asparagine linkage.

scholarly journals A cautionary perspective regarding the isolation and serial propagation of SARS-CoV-2 in Vero cells

npj Vaccines ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Simon G. P. Funnell ◽  
Babak Afrough ◽  
John James Baczenas ◽  
Neil Berry ◽  
Kevin R. Bewley ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Genetic Variants ◽  
Animal Studies ◽  
Vero Cells ◽  
In Vitro Assays ◽  
Critical Research ◽  
Furin Cleavage ◽  
Furin Cleavage Site

AbstractAn array of SARS-CoV-2 virus variants have been isolated, propagated and used in in vitro assays, in vivo animal studies and human clinical trials. Observations of working stocks of SARS-CoV-2 suggest that sequential propagation in Vero cells leads to critical changes in the region of the furin cleavage site, which significantly reduce the value of the working stock for critical research studies. Serially propagating SARS-CoV-2 in Vero E6 cells leads to rapid increases in genetic variants while propagation in other cell lines (e.g. Vero/hSLAM) appears to mitigate this risk thereby improving the overall genetic stability of working stocks. From these observations, investigators are urged to monitor genetic variants carefully when propagating SARS-CoV-2 in Vero cells.

scholarly journals Effect of 1-(phenyl)-N’-(4-methoxybenzylidene)-9H-pyrido[3,4-b] indole-3-carbohydrazide on in vitro poliovirus replication

2015 ◽  
Vol 65 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Patricia Regina Santos ◽  
Anelise S. Nazari Formagio ◽  
Benedito Prado Dias Filho ◽  
Celso Vataru Nakamura ◽  
Maria Helena Sarragiotto ◽  
...  
Keyword(s):  
Host Cell ◽  
Mode Of Action ◽  
Cytopathic Effect ◽  
Vero Cells ◽  
Replication Cycle ◽  
Clinical Use ◽  
Future Studies ◽  
Post Exposure

Abstract The effect of the alkaloid 1-(phenyl)-N’-(4-methoxybenzylidene)- 9H-pyrido[3,4-b]indole-3-carbohydrazide (PMC) on the poliovirus (PV) replication cycle in Vero cells was assayed by inhibition of the cytopathic effect (CPE) and inhibition of plaque forming units (PFU). Both methodologies suggested that the mode of action was avoidance of infection progression in the host cell. The compound was able to prevent CPE and PFU formation when the cells were pretreated with PMC for 24 h prior to PV infection. In addition, when the alkaloid was continuously maintained in the infected cultures, the spread of PV to adjacent cells was impaired. The pre-exposure and post-exposure prophylactic applications are possible situations in which an anti-PV drug might be used. Future studies are needed to elucidate the PMC mode of action and verify the feasibility of PMC use in vivo. No antipicornavirus agent is currently approved for clinical use

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