scholarly journals The inhibitory action of transfer factors on lysis ofEscherichia coliK 12 by phages μ 2 and Φ 2

1970 ◽  
Vol 16 (2) ◽  
pp. 215-224 ◽  
Author(s):  
J. S. Pitton ◽  
E. S. Anderson
Keyword(s):  
Transfer Factors ◽  
Resistance Factors ◽  
Specific Phage ◽  
Agar Layer ◽  
K 12 ◽  
Female Specific ◽  
Male Specific ◽  
R Factors ◽  
Selection Of

SUMMARYA selection offi+resistance factors and transfer factors, when introduced into K 12F+, showed a range of inhibitory activity of lysis by the male-specific phage μ 2. This range can be used to subdivide thefi+factors intofi+1,fi+2,fi+3andfi+4classes, according to the degree of inhibition of μ 2 lysis. To this subdivision can be added restriction of the ‘female-specific’ phage φ 2.Introduction of all thefi+factors tested into K 12 HfrH totally inhibited lysis by μ 2 in spot tests, but with twofi+1and onefi+2factors visible lysis was obtained in agar-layer tests. These three factors caused least inhibition of transfer ofproby HfrH. It can be assumed that both tests reflect lower inhibition of sex fimbrial formation by thesefi+factors than by the remainder.Thefi−factors, when introduced into K 12, can be subdivided on the basis of restrictive effects on phage φ 2.These effects can be added to phage restriction in the salmonellae for the purposes of further classification of the transfer factors and R-factors.

scholarly journals The Isolation and Oharacterization of An Rna Bacteriophage

1964 ◽  
Vol 17 (3) ◽  
pp. 719 ◽  
Author(s):  
CI Davern
Keyword(s):  
Escherichia Coli ◽  
Dna Synthesis ◽  
Culture Medium ◽  
Buoyant Density ◽  
Sedimentation Coefficient ◽  
Caesium Chloride ◽  
Specific Phage ◽  
K 12 ◽  
Male Specific ◽  
Rna Phage

An enrichment procedure for the isolation of RNA bacteriophage is described. The method involves the inoculation of sewage samples into cultures of Escherichia coli K-12 Hfr under conditions where DNA synthesis is restricted by the addition of 5-fiuorodeoxyuridine to the culture medium. Six phage isolates were made and all of them were shown to be male-specific. One of the male-specific phage was further characterized as an RNA phage, having very similar properties to RNA phage already isolated in other parts oftha world. This RNA phage has a buoyant density of 1�42 g/cm3 in caesium chloride. and has a sedimentation coefficient of 79'5 Sin O'Ol:M Tria-HOI buffer, pH 7� 4, at 20�0.

scholarly journals Characteristics ofE. coliK12 strains carrying both an F prime and an R factor

1970 ◽  
Vol 16 (1) ◽  
pp. 113-122 ◽  
Author(s):  
N. S. Willetts ◽  
D. J. Finnegan
Keyword(s):  
Escherichia Coli ◽  
Plaque Formation ◽  
Male And Female ◽  
R Factor ◽  
Specific Phage ◽  
Simultaneous Loss ◽  
K 12 ◽  
Female Specific ◽  
Surface Exclusion

SUMMARYThe interrelationship between an F prime and an F-like or I-like R factor was studied inEscherichia coliK 12 strains carrying both. The donorability of such strains suggested that these plasmids were transferred independently by their own transfer systems. Plaque formation by several male- and female-specific phage was tested; the inhibition by Flacof several female-specific phage was not affected by an F-like R factor. Neither did an R factor affect the incompatibility between Flacand Fhis. However, the surface exclusion characteristic of Flacwas lost in the presence of an F-like R factor. This is probably closely related to the simultaneous loss of donorability, the F-pilus, and the f+antigen: all may be the result of the inhibition by an R product of the formation or activity of a single F product.

Use of photodynamic therapy for photodamage skin (review of literature)

2019 ◽  
Vol 1 (7) ◽  
pp. 19-23
Author(s):  
S. I. Surkichin ◽  
N. V. Gryazeva ◽  
L. S. Kholupova ◽  
N. V. Bochkova
Keyword(s):  
Photodynamic Therapy ◽  
Comparative Evaluation ◽  
Clinical Manifestations ◽  
Light Sources ◽  
Review Of Literature ◽  
Photosensitizing Agents ◽  
Selection Of

The article provides an overview of the use of photodynamic therapy for photodamage of the skin. The causes, pathogenesis and clinical manifestations of skin photodamage are considered. The definition, principle of action of photodynamic therapy, including the sources of light used, the classification of photosensitizers and their main characteristics are given. Analyzed studies that show the effectiveness and comparative evaluation in the selection of various light sources and photosensitizing agents for photodynamic therapy in patients with clinical manifestations of photodamage.

Philosophcal review of h. white̕s tropological theory in the context of the new philosophy of history

2020 ◽  
Vol 3 (152) ◽  
pp. 92-99
Author(s):  
S. M. Geiko ◽  
◽  
O. D. Lauta
Keyword(s):  
Modern Science ◽  
Historical Knowledge ◽  
Text Organization ◽  
The Social ◽  
History Of ◽  
Actual Material ◽  
The Common ◽  
Historical Nature ◽  
Selection Of

The article provides a philosophical analysis of the tropological theory of the history of H. White. The researcher claims that history is a specific kind of literature, and the historical works is the connection of a certain set of research and narrative operations. The first type of operation answers the question of why the event happened this way and not the other. The second operation is the social description, the narrative of events, the intellectual act of organizing the actual material. According to H. White, this is where the set of ideas and preferences of the researcher begin to work, mainly of a literary and historical nature. Explanations are the main mechanism that becomes the common thread of the narrative. The are implemented through using plot (romantic, satire, comic and tragic) and trope systems – the main stylistic forms of text organization (metaphor, metonymy, synecdoche, irony). The latter decisively influenced for result of the work historians. Historiographical style follows the tropological model, the selection of which is determined by the historian’s individual language practice. When the choice is made, the imagination is ready to create a narrative. Therefore, the historical understanding, according to H. White, can only be tropological. H. White proposes a new methodology for historical research. During the discourse, adequate speech is created to analyze historical phenomena, which the philosopher defines as prefigurative tropological movement. This is how history is revealed through the art of anthropology. Thus, H. White’s tropical history theory offers modern science f meaningful and metatheoretically significant. The structure of concepts on which the classification of historiographical styles can be based and the predictive function of philosophy regarding historical knowledge can be refined.

Using clusterization principles for the selection of repair sections of main oil pipelines based on diagnostic data

2011 ◽  
Vol 8 (1) ◽  
pp. 201-210
Author(s):  
R.M. Bogdanov
Keyword(s):  
Cluster Analysis ◽  
Defect Density ◽  
Density Variation ◽  
Distance Functions ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Classification Of Images ◽  
Main Oil Pipeline ◽  
Selection Of

The problem of determining the repair sections of the main oil pipeline is solved, basing on the classification of images using distance functions and the clustering principle, The criteria characterizing the cluster are determined by certain given values, based on a comparison with which the defect is assigned to a given cluster, procedures for the redistribution of defects in cluster zones are provided, and the cluster zones parameters are being changed. Calculations are demonstrating the range of defect density variation depending on pipeline sections and the universal capabilities of linear objects configuration with arbitrary density, provided by cluster analysis.

Negative Staining: a Valuable Technique for Studying Subcellular Components

1997 ◽  
Vol 3 (S2) ◽  
pp. 341-342
Author(s):  
Sara E. Miller
Keyword(s):  
Negative Staining ◽  
Cell Organelles ◽  
Preparation Time ◽  
Nucleic Acid Probes ◽  
Virus Identification ◽  
High Particle ◽  
Thin Sectioning ◽  
Particle Counts ◽  
Selection Of

Negative staining is the most frequently used procedure for preparing particulate specimens, e.g., cell organelles, macromolecules, and viruses, for electron microscopy (Figs. 1-4). The main advantage is that it is rapid, requiring only minutes of preparation time. Another is that it avoids some of the harsh chemicals, e.g., organic solvents, used in thin sectioning. Also, it does not require advanced technical skill. It is widely used in virology, both in classification of viruses as well as diagnosis of viral diseases. Notwithstanding the necessity for fairly high particle counts, virus identification by negative staining is advantageous in not requiring specific reagents such as antibodies, nucleic acid probes, or protein standards which necessitate prior knowledge of potential pathogens for selection of the proper reagent. Furthermore, it does not require viable virions as does growth in tissue culture. Another procedure that uses negative contrasting is ultrathin cryosectioning (Fig. 5).In 1954 Farrant was the first to publish negatively stained material, ferritin particles.

scholarly journals Monotonic Functions Method and Its Application to Staging of Patients with Prostate Cancer According to Pretreatment Data

2021 ◽  
Vol 11 (9) ◽  
pp. 3836
Author(s):  
Valeri Gitis ◽  
Alexander Derendyaev ◽  
Konstantin Petrov ◽  
Eugene Yurkov ◽  
Sergey Pirogov ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Learning Algorithm ◽  
Binary Classification ◽  
Preoperative Staging ◽  
Threshold Value ◽  
Logical Function ◽  
Adequate Treatment ◽  
Monotonic Functions ◽  
Selection Of

Prostate cancer is the second most frequent malignancy (after lung cancer). Preoperative staging of PCa is the basis for the selection of adequate treatment tactics. In particular, an urgent problem is the classification of indolent and aggressive forms of PCa in patients with the initial stages of the tumor process. To solve this problem, we propose to use a new binary classification machine-learning method. The proposed method of monotonic functions uses a model in which the disease’s form is determined by the severity of the patient’s condition. It is assumed that the patient’s condition is the easier, the less the deviation of the indicators from the normal values inherent in healthy people. This assumption means that the severity (form) of the disease can be represented by monotonic functions from the values of the deviation of the patient’s indicators beyond the normal range. The method is used to solve the problem of classifying patients with indolent and aggressive forms of prostate cancer according to pretreatment data. The learning algorithm is nonparametric. At the same time, it allows an explanation of the classification results in the form of a logical function. To do this, you should indicate to the algorithm either the threshold value of the probability of successful classification of patients with an indolent form of PCa, or the threshold value of the probability of misclassification of patients with an aggressive form of PCa disease. The examples of logical rules given in the article show that they are quite simple and can be easily interpreted in terms of preoperative indicators of the form of the disease.

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