Calculation of the Electromagnetic Field Around a Microtubule

Microtubules are important structures in the cytoskeleton which organizes the cell. A single microtubule is composed of electrically polar structures, tubulin heterodimers, which have a strong electric dipole moment. Vibrations are expected to be generated in microtubules, thus tubulin heterodimers oscillate as electric dipoles. This gives rise to an electromagnetic field which is detected around the cells. We calculate here the electromagnetic field of microtubules if they are excited at 1 GHz. This paper includes work done for the bachelor thesis of the first author.

Correction: Electro-acoustic behavior of the mitotic spindle: A semi-classical coarse-grained model (PLoS ONE (2014) 9:1 (e86501) DOI: 10.1371/journal.pone.0086501)

There are errors in the values reported for parameters a, b, c, and V in Table 1. Please see the correct Table 1 here. [Table Preasented]. There is an error in the equation in the third sentence in the “The arrangement of microtubules” subsection of the Models section. The equation describing the distance from the origin of the coordinate system for MTOC placement on the x-axis is incorrect. Please see the correct equation here: [Formola Presented]. There is an error in the Eq (6) in the “Calculation of the intensity of the electric field” subsection of the Models section. Please see the correct Eq (6) here: [Formola Presented]. There is an error in the Eq (7) in the “Calculation of the intensity of the electric field” subsection of the Models section. Please see the correct Eq (7) here: [Formola Presented]. The authors confirm that the code used in the modelling do not contain the errors in parameters and equations, which affect only the description of the models. The results and conclusions are therefore unaffected by these corrections to the reporting of the methodology. There are errors in the scale of the y-axis shown for the bottom panel of Fig 10. Please see the correct Fig 10 here.[Figure Presented]

Deformation pattern in vibrating microtubule: Structural mechanics study based on an atomistic approach

The mechanical properties of microtubules are of great importance for understanding their biological function and for applications in artificial devices. Although microtubule mechanics has been extensively studied both theoretically and experimentally, the relation to its molecular structure is understood only partially. Here, we report on the structural analysis of microtubule vibration modes calculated by an atomistic approach. Molecular dynamics was applied to refine the atomic structure of a microtubule and a C α elastic network model was analyzed for its normal modes. We mapped fluctuations and local deformations up to the level of individual aminoacid residues. The deformation is mode-shape dependent and principally different in α-tubulins and β-tubulins. Parts of the tubulin dimer sequence responding specifically to longitudinal and radial stress are identified. We show that substantial strain within a microtubule is located both in the regions of contact between adjacent dimers and in the body of tubulins. Our results provide supportive evidence for the generally accepted assumption that the mechanics of microtubules, including its anisotropy, is determined by the bonds between tubulins

Tubulin response to intense nanosecond-scale electric field in molecular dynamics simulation

Intense pulsed electric fields are known to act at the cell membrane level and are already being exploited in biomedical and biotechnological applications. However, it is not clear if electric pulses within biomedically-attainable parameters could directly influence intra-cellular components such as cytoskeletal proteins. If so, a molecular mechanism of action could be uncovered for therapeutic applications of such electric fields. To help clarify this question, we first identified that a tubulin heterodimer is a natural biological target for intense electric fields due to its exceptional electric properties and crucial roles played in cell division. Using molecular dynamics simulations, we then demonstrated that an intense - yet experimentally attainable - electric field of nanosecond duration can affect the bβ-tubulin’s C-terminus conformations and also influence local electrostatic properties at the GTPase as well as the binding sites of major tubulin drugs site. Our results suggest that intense nanosecond electric pulses could be used for physical modulation of microtubule dynamics. Since a nanosecond pulsed electric field can penetrate the tissues and cellular membranes due to its broadband spectrum, our results are also potentially significant for the development of new therapeutic protocols

Evolution of avalanche conducting states in electrorheological liquids

Charge transport in electrorheological fluids is studied experimentally under strongly nonequlibrium conditions. By injecting an electrical current into a suspension of conducting nanoparticles we are able to initiate a process of self-organization which leads, in certain cases, to formation of a stable pattern which consists of continuous conducting chains of particles. The evolution of the dissipative state in such system is a complex process. It starts as an avalanche process characterized by nucleation, growth, and thermal destruction of such dissipative elements as continuous conducting chains of particles as well as electroconvective vortices. A power-law distribution of avalanche sizes and durations, observed at this stage of the evolution, indicates that the system is in a self-organized critical state. A sharp transition into an avalanche-free state with a stable pattern of conducting chains is observed when the power dissipated in the fluid reaches its maximum. We propose a simple evolution model which obeys the maximum power condition and also shows a power-law distribution of the avalanche sizes.Comment: 15 pages, 6 figure

The efficacy of the thyroid peroxidase marker for distinguishing follicular thyroid carcinoma from follicular adenoma

Aim: Expression of thyroid peroxidase (TPO) in the thyroid gland tissue is well known as a sensitive marker of the thyroid malignancy. We have evaluated immunohistochemical assay of TPO for distinguishing follicular thyroid carcinoma from follicular adenoma. Materials and Methods: Sections of formalin-fixed tissues obtained from 92 patients with thyroid tumors (52 follicular carcinomas and 40 follicular adenomas including the Hurthle cell type) were analyzed using a monoclonal antibody (TPO mAb 47) and the avidin-biotin peroxidase complex immunohistochemical technique. Lesions with staining of more than 80% of the follicular cells/specimen were considered benign, while less than 80% were considered malignant. Results: TPO immunostaining correlated with the histopathological diagnosis in 24/40 cases of follicular adenomas and 41/52 cases of follicular carcinomas, giving a specificity of 60% and a sensitivity of 79%. Conclusion: These results suggest that immunohistochemical assay of TPO expression has limited value for the differential diagnosis of follicular thyroid carcinoma from thyroid follicular adenoma.Цель: уровень экспрессии тироидной пероксидазы (ТПО) в ткани щитовидной железы является чувствительным маркером малигнизации этого органа. В работе представлено попытку оценки метода иммуногистохимический детекции ТПО для дифференциальной диагностики фолликулярной карциномы и фолликулярной аденомы щитовидной железы (ФКЩЖ и ФАЩЖ соответственно). Материалы и методы: срезы ткани, зафиксированные в формалине, были получены у 92 пациентов с опухолями щитовидной железы (52 случая — ФКЩЖ и 40 — ФАЩЖ, в том числе тип с клетками Хюртля). Для иммуногистохимического анализа этих срезов использовали моноклональные антитела против ТПО (ТРОmAb47) и авидин-биотиновый комплекс. Препараты опухолей, содержащих более 80% позитивно окрашенных фолликулярных клеток, признавали доброкачественными, а те, что содержали менее 80% таких клеток, — злокачественными. Результаты: интенсивность иммуноокрашивания препаратов коррелировала с гистопатологическим диагнозом в 24 из 40 случаев ФАЩЖ и в 41 из 52 случаев ФКЩЖ. При этом чувствительность метода составляла 79%, специфичность — 60%. Выводы: иммуногистохимический анализ ТПО имеет недостаточную специфичность для дифференциальной диагностики фолликулярной карциномы и фолликулярной аденомы

A machine learning approach to quantifying the specificity of colour–emotion associations and their cultural differences

The link between colour and emotion and its possible similarity across cultures are questions that have not been fully resolved. Online, 711 participants from China, Germany, Greece and the UK associated 12 colour terms with 20 discrete emotion terms in their native languages. We propose a machine learning approach to quantify (a) the consistency and specificity of colour–emotion associations and (b) the degree to which they are country-specific, on the basis of the accuracy of a statistical classifier in (a) decoding the colour term evaluated on a given trial from the 20 ratings of colour–emotion associations and (b) predicting the country of origin from the 240 individual colour–emotion associations, respectively. The classifier accuracies were significantly above chance level, demonstrating that emotion associations are to some extent colour-specific and that colour–emotion associations are to some extent country-specific. A second measure of country-specificity, the in-group advantage of the colour-decoding accuracy, was detectable but relatively small (6.1%), indicating that colour–emotion associations are both universal and culture-specific. Our results show that machine learning is a promising tool when analysing complex datasets from emotion researc