scholarly journals Improving Phage-Biofilm In Vitro Experimentation

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1175
Author(s):  
Stephen T. Abedon ◽  
Katarzyna M. Danis-Wlodarczyk ◽  
Daniel J. Wozniak ◽  
Matthew B. Sullivan
Keyword(s):  
Viable Count ◽  
Bacterial Biofilms ◽  
In Vitro Experiments ◽  
Experimental Conditions ◽  
Biofilm Growth ◽  
Bacterial Ecology ◽  
End Point ◽  
Biofilm Disruption ◽  
Free Phage

Bacteriophages or phages, the viruses of bacteria, are abundant components of most ecosystems, including those where bacteria predominantly occupy biofilm niches. Understanding the phage impact on bacterial biofilms therefore can be crucial toward understanding both phage and bacterial ecology. Here, we take a critical look at the study of bacteriophage interactions with bacterial biofilms as carried out in vitro, since these studies serve as bases of our ecological and therapeutic understanding of phage impacts on biofilms. We suggest that phage-biofilm in vitro experiments often may be improved in terms of both design and interpretation. Specific issues discussed include (a) not distinguishing control of new biofilm growth from removal of existing biofilm, (b) inadequate descriptions of phage titers, (c) artificially small overlying fluid volumes, (d) limited explorations of treatment dosing and duration, (e) only end-point rather than kinetic analyses, (f) importance of distinguishing phage enzymatic from phage bacteriolytic anti-biofilm activities, (g) limitations of biofilm biomass determinations, (h) free-phage interference with viable-count determinations, and (i) importance of experimental conditions. Toward bettering understanding of the ecology of bacteriophage-biofilm interactions, and of phage-mediated biofilm disruption, we discuss here these various issues as well as provide tips toward improving experiments and their reporting.

scholarly journals Antibacterial Activity of Blue Light against Nosocomial Wound Pathogens Growing Planktonically and as Mature Biofilms

2016 ◽  
Vol 82 (13) ◽  
pp. 4006-4016 ◽  
Author(s):  
Fenella D. Halstead ◽  
Joanne E. Thwaite ◽  
Rebecca Burt ◽  
Thomas R. Laws ◽  
Marina Raguse ◽  
...  
Keyword(s):  
Blue Light ◽  
Mammalian Cells ◽  
Wide Spectrum ◽  
Great Promise ◽  
Bacterial Biofilms ◽  
Light Spectrum ◽  
Biofilm Growth ◽  
Content Type ◽  
Elizabethkingia Meningoseptica

ABSTRACTThe blue wavelengths within the visible light spectrum are intrinisically antimicrobial and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram positive and negative) and fungi. Furthermore, blue light is equally effective against both drug-sensitive and -resistant members of target species and is less detrimental to mammalian cells than is UV radiation. Blue light is currently used for treating acnes vulgaris andHelicobacter pyloriinfections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms, the key growth mode of bacteria involved in clinical infections. Here we report the findings of a multicenterin vitrostudy performed to assess the antimicrobial activity of 400-nm blue light against bacteria in both planktonic and biofilm growth modes. Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprisingAcinetobacter baumannii,Enterobacter cloacae,Stenotrophomonas maltophilia,Pseudomonas aeruginosa,Escherichia coli,Staphylococcus aureus,Enterococcus faecium,Klebsiella pneumoniae, andElizabethkingia meningoseptica. All planktonic-phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5-log10decrease in viability after 15 to 30 min of exposure (54 J/cm2to 108 J/cm2). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure. These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications.IMPORTANCEBlue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g., wound closure during surgery). This warrants further investigation.

An Analysis of the Postgastrula Differentiation of the Hypomere

Development ◽  
1961 ◽  
Vol 9 (2) ◽  
pp. 294-309
Author(s):  
Cyril V. Finnegan
Keyword(s):  
Early Age ◽  
In Vitro Experiments ◽  
Experimental Conditions ◽  
Tissue Mass ◽  
Intimate Association ◽  
Insight Into

Since the publication of earlier papers (Finnegan, 1953, 1955) the investigation of the capacity of the salamander hypomeric mesoderm for histogenesis under a variety of experimental conditions has continued. It is perhaps prudent at this time to initiate a series of reports with results obtained from in vitro experiments which were designed to gain some insight into the roles of competence, tissue mass, and endodermal influence relative to hypomeric differentiation in Ambystoma. This portion of the mesoderm is destined to undergo its differentiation far removed from the dorsal axial influences of the chorda-mesoderm but with its inner (splanchnic) material in rather intimate association with the endoderm, a tissue known to be determined at an early age and metabolically active, two conditions which lead one to suspect it of inductor potentialities (Nieuwkoop, 1947; Copenhaver, 1955).

Bacterial Biofilms in Infective Endocarditis – A complex in vitro - Model to Investigate Emerging Technologies of Antimicrobial Cardiovascular Device Coatings

2020 ◽  
Author(s):  
Laura Kursawe ◽  
Alexander Lauten ◽  
Marc Martinović ◽  
Klaus Affeld ◽  
Ulrich Kertzscher ◽  
...  
Keyword(s):  
Infective Endocarditis ◽  
Heart Valves ◽  
In Vitro Model ◽  
Bacterial Biofilm ◽  
Bacterial Biofilms ◽  
Aortic Valves ◽  
Biofilm Growth ◽  
Vitro Model ◽  
Biofilm Development

<p><strong>Objective:</strong> Most biofilm flow-chambers are designed for standardized homogeneous biofilms for research purposes. These do not mimic the complexity of prosthetic heart valves, which consist of both artificial and biological material.</p> <p>Infective endocarditis (IE) is still associated with a high morbidity and mortality. IE is characterized by bacterial biofilms of the endocardium leading to destruction of the valve. Current research demonstrates that about one quarter of the patients with formal surgery indication cannot undergo surgery. This group of patients needs further options of therapy, but due to a lack of models for IE, prospects of research are low.</p> <p>Therefore, the purpose of this project was to establish an in vitro - model of infective endocarditis to allow growth of bacterial biofilms on porcine aortic valves, serving as baseline for further research.</p> <p><strong>Methods and Results: </strong>A pulsatile two-chamber circulation model was constructed that kept native porcine aortic valves under sterile, physiologic hemodynamic and temperature conditions. To exclude external contamination, sterility tests with sterile culture media were performed for 24h. During this time period, no growth of microorganisms was observed in the system and cultures after plating on standard media remained negative.</p> <p>The system was inoculated with Staphylococcus epidermidis PIA 8400 to create biofilms on porcine aortic valves. Porcine aortic roots were incubated in this system for increasing periods of time and bacterial titration to evaluate bacterial growth and biofilm development on the valves. After incubation, specimens were embedded and tissue sections were analyzed by Fluorescence in situ hybridization (FISH) for direct visualization of the biofilms and bacterial activity.</p> <p>Pilot tests for biofilm growth showed monospecies colonization consisting of cocci with time- and inocula-dependent increase. FISH visualized biofilms with ribosome-containing, and thus metabolic active cocci, tissue infiltration and similar colonization pattern as observed by FISH in human IE heart valves infected by S. epidermidis.</p> <p><strong>Conclusion:</strong> These results demonstrate the establishment of a novel complex in vitro - model for bacterial biofilm growth on porcine aortic roots. The model will allow identifying predilection sites of heart valves for bacterial adhesion and biofilm growth and it may serve as baseline for further research on IE therapy and prevention, e.g. the development of antimicrobial transcatheter approaches to IE.</p>

In Vitro Models for Studying Renal Stone Formation: A Clear Alternative

1998 ◽  
Vol 26 (4) ◽  
pp. 481-503
Author(s):  
Felix Grases ◽  
Rafael M. Prieto ◽  
Antonia Costa-Bauzá
Keyword(s):  
Renal Stone ◽  
Stone Formation ◽  
Renal Stones ◽  
Renal Calculi ◽  
In Vitro Models ◽  
Laboratory Animals ◽  
In Vitro Experiments ◽  
Experimental Conditions

This paper discusses the limitations of using laboratory animals for direct in vivo observation of the development of renal stones. In fact, the majority of hypotheses related to mechanisms of stone formation have been based on the results of in vitro experiments. The relevance of in vitro experiments that allow the study of urolithiasis depends upon the degree of correspondence between the experimental conditions and those prevailing in the stone-forming kidney in vivo. For this reason, several in vitro experimental systems that attempt to reproduce the conditions found in vivo have been developed in order to study renal stone formation, which have been classified into two main groups: a) models to study papillary stone formation; and b) models to study “sedimentary” stone formation. These models are briefly described in this paper, and the information obtained was compared with that resulting from a study of the fine structure of real human renal calculi, in order to prove the validity of the models. It was concluded that the experimental in vitro models can closely reproduce the renal conditions under which human calculi are developed. This allows important data to be obtained about the aetiology of renal lithiasis, which is of great relevance to the development of effective treatments for this disease. Therefore, experimental in vitro models constitute a clear alternative to the use of laboratory animals.

scholarly journals Cationic, anionic and neutral dyes: effects of photosensitizing properties and experimental conditions on the photodynamic inactivation of pathogenic bacteria

2013 ◽  
Vol 11 (4) ◽  
pp. 590-599 ◽  
Author(s):  
Sonia Sabbahi ◽  
Layla Ben Ayed ◽  
Abdellatif Boudabbous
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Irradiation Time ◽  
Chemical Properties ◽  
Neutral Red ◽  
Viable Count ◽  
Photodynamic Inactivation ◽  
Experimental Conditions ◽  
Significant Difference

The aim of this study was to evaluate the photobactericidal effect of four photosensitizers (PSs) with different structural and physico-photochemical properties, namely mesotetracationic porphyrin (T4MPyP), dianionic rose Bengal (RB), monocationic methylene blue (MB) and neutral red (NR). Their photokilling activity was tested in vitro on pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) suspended in nutrient broth (NB) and in phosphate buffered saline (PBS) through following their influence on the PSs antimicrobial efficacy. Photodynamic inactivation (PDI) experiments were performed using visible light (L) and different PSs concentrations (20–70 μM). The ability of these PSs to mediate bacterial photodynamic inactivation was investigated as a function of type of PS and its concentrations, spectral and physico-chemical properties, bacterial strain, irradiation time and suspending medium. Indeed, they showed antibacterial effects against S. aureus and P. aeruginosa with significant difference in potency. Staphylococcus aureus suspended in NB showed 0.92 log units reduction in viable count in the presence of T4MPyP at 20 μM. Changing the suspending medium from NB to PBS, S. aureus was successfully photoinactivated by T4MPyP (20 μM) when suspended in PBS at least time exposure (10 and 30 min), followed by MB and RB.

scholarly journals Microencapsulation of Bacteriophage Felix O1 into Chitosan-Alginate Microspheres for Oral Delivery

2008 ◽  
Vol 74 (15) ◽  
pp. 4799-4805 ◽  
Author(s):  
Yongsheng Ma ◽  
Jennifer C. Pacan ◽  
Qi Wang ◽  
Yongping Xu ◽  
Xiaoqing Huang ◽  
...  
Keyword(s):  
Oral Delivery ◽  
Gastric Fluid ◽  
Viable Count ◽  
Simulated Gastric Fluid ◽  
Intestinal Fluid ◽  
Simulated Intestinal Fluid ◽  
Testing Period ◽  
Acidic Environments ◽  
Free Phage

ABSTRACT This paper reports the development of microencapsulated bacteriophage Felix O1 for oral delivery using a chitosan-alginate-CaCl2 system. In vitro studies were used to determine the effects of simulated gastric fluid (SGF) and bile salts on the viability of free and encapsulated phage. Free phage Felix O1 was found to be extremely sensitive to acidic environments and was not detectable after a 5-min exposure to pHs below 3.7. In contrast, the number of microencapsulated phage decreased by 0.67 log units only, even at pH 2.4, for the same period of incubation. The viable count of microencapsulated phage decreased only 2.58 log units during a 1-h exposure to SGF with pepsin at pH 2.4. After 3 h of incubation in 1 and 2% bile solutions, the free phage count decreased by 1.29 and 1.67 log units, respectively, while the viability of encapsulated phage was fully maintained. Encapsulated phage was completely released from the microspheres upon exposure to simulated intestinal fluid (pH 6.8) within 6 h. The encapsulated phage in wet microspheres retained full viability when stored at 4°C for the duration of the testing period (6 weeks). With the use of trehalose as a stabilizing agent, the microencapsulated phage in dried form had a 12.6% survival rate after storage for 6 weeks. The current encapsulation technique enables a large proportion of bacteriophage Felix O1 to remain bioactive in a simulated gastrointestinal tract environment, which indicates that these microspheres may facilitate delivery of therapeutic phage to the gut.

scholarly journals In Silico Experiments in Scientific Papers on Molecular Biology

2011 ◽  
Vol 24 (2) ◽  
pp. 23-42
Author(s):  
Sabrina Moretti
Keyword(s):  
Molecular Biology ◽  
In Silico ◽  
In Vitro Experiments ◽  
Technical Object ◽  
Experimental Conditions ◽  
Biological Phenomena ◽  
Scientific Papers

This article explores the role of the so-called in silico experiments used in molecular biology. It is based on the analysis of some papers that present scientific applications which rely on in silico experiments. By means of this study I found two basic ways of viewing them. According to the first view, the in silico experiment is a computer program that realizes some specific operations: it constitutes some particular experimental conditions, which allow us to investigate biological phenomena, and which complement those present in in vivo and in vitro experiments. According to the second view, in silico experimentation has a different meaning, which corresponds more closely to the meaning of “simulation”: its identity is linked to that of the “model” used to construct such simulation. The authors of the analysed papers never express an intention to standardize a model, so its meaning remains contingent, and cannot be turned into a technical object.

Humoral induction of pyloric rhythmic output in lobster stomatogastric ganglion: in vivo and in vitro studies

1992 ◽  
Vol 163 (1) ◽  
pp. 209-230
Author(s):  
E. Rezer ◽  
M. Moulins
Keyword(s):  
Blood Serum ◽  
Stomatogastric Ganglion ◽  
In Vitro Studies ◽  
In Vitro Experiments ◽  
Experimental Conditions ◽  
Pyloric Network ◽  
Pyloric Rhythm

In the lobster Jasus lalandii, 14 neurones of the stomatogastric ganglion (STG) are organized in a network that produces rhythmic pyloric outputs. In vitro experiments have shown that the STG neurones receive, via the stomatogastric nerve (stn), neuromodulatory inputs that influence the expression of the bursting properties of the neurones and the ability of the network to produce its rhythmic output. In contrast to these in vitro observations, in vivo transection of the stn does not abolish the pyloric rhythm. Rhythmic output can be recorded by electromyography immediately after stn transection and for up to 2 years afterwards. We have shown that, under these experimental conditions, the STG appears to be isolated from any neuronal input that might account for the maintenance of the rhythmic output. Experiments carried out in the 2 days after stn transection showed that an in vitro preparation of the isolated STG was unable to produce any rhythmic output, but blood serum added to the system could restore the pyloric output. These results suggest strongly that the pyloric network receives neural and humoral modulatory influences in parallel and that each type of influence alone is able to maintain the bursting capability of the pyloric neurones.

scholarly journals Revisiting the Non-Coding Nature of Pospiviroids

Cells ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 265
Author(s):  
Konstantina Katsarou ◽  
Charith Raj Adkar-Purushothama ◽  
Emilios Tassios ◽  
Martina Samiotaki ◽  
Christos Andronis ◽  
...  
Keyword(s):  
Unknown Function ◽  
Bioinformatic Analysis ◽  
Economic Losses ◽  
In Vitro Experiments ◽  
Experimental Conditions ◽  
Circular Form ◽  
Size And Structure

Viroids are small, circular, highly structured pathogens that infect a broad range of plants, causing economic losses. Since their discovery in the 1970s, they have been considered as non-coding pathogens. In the last few years, the discovery of other RNA entities, similar in terms of size and structure, that were shown to be translated (e.g., cirRNAs, precursors of miRNA, RNA satellites) as well as studies showing that some viroids are located in ribosomes, have reignited the idea that viroids may be translated. In this study, we used advanced bioinformatic analysis, in vitro experiments and LC-MS/MS to search for small viroid peptides of the PSTVd. Our results suggest that in our experimental conditions, even though the circular form of PSTVd is found in ribosomes, no produced peptides were identified. This indicates that the presence of PSTVd in ribosomes is most probably not related to peptide production but rather to another unknown function that requires further study.

Neurofilaments and Paired Helical Filaments

1985 ◽  
Vol 43 ◽  
pp. 740-743
Author(s):  
J. Metuzals
Keyword(s):  
Animal Model ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Giant Axon ◽  
Paired Helical Filaments ◽  
Squid Giant Axon ◽  
In Vitro Experiments ◽  
Thin Sections ◽  
Structural Relationships

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.

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