Primary 3D Culture of Human Thyroid Follicle-Like Structures in Platelet Lysate-Based Gel.

The results of 3D culturing of human thyroid follicle-like structures in a gel based on platelet lysate at the gel-air interface are presented. During culturing up to 4 months, no new follicle-like structures were formed and none were destroyed. During the first 2 months, most follicle-like structures increased in size; then, their grown decelerated, but they retained viability. Ki-67+ cells were observed in the majority of follicle-like structures. Most of them produced thyroglobulin. Follicle-like structures get closer, the number of contacts between them increased, and cluster appeared. Thus, the developed 3D culturing system in a gel based on platelet lysate is an adequate approach for maintaining structure and functional activity of human follicle-like structures in vitro for at least 2 months.

A definition of bioinks and their distinction from biomaterial inks.

Biofabrication aims to fabricate biologically functional products through bioprinting or bioassembly (Groll et al 2016 Biofabrication 8 013001). In biofabrication processes, cells are positioned at defined coordinates in three-dimensional space using automated and computer controlled techniques (Moroni et al 2018 Trends Biotechnol. 36 384-402), usually with the aid of biomaterials that are either (i) directly processed with the cells as suspensions/dispersions, (ii) deposited simultaneously in a separate printing process, or (iii) used as a transient support material. Materials that are suited for biofabrication are often referred to as bioinks and have become an important area of research within the field. In view of this special issue on bioinks, we aim herein to briefly summarize the historic evolution of this term within the field of biofabrication. Furthermore, we propose a simple but general definition of bioinks, and clarify its distinction from biomaterial inks.

Terahertz radiation from bismuth surface induced by femtosecond laser pulses.

We report on the first experimental observation of terahertz (THz) wave generation from bismuth mono- and polycrystalline samples irradiated by femtosecond laser pulses. Dependencies of the THz signal on the crystal orientation, optical pulse energy, incidence angle, and polarization are presented and discussed together with features of the sample surfaces. The optical-to-THz conversion efficiency was up to two orders of magnitude higher than for metal at a moderate fluence of ∼1 mJ/cm2. We also found nonlinear effects not previously observed using other metal and semiconductor materials: (a) asymmetry of THz response with respect to a half-turn of a sample around its normal, (b) THz polarization control by orientation of the sample surface, and

[PERIPHERAL AUTONOMOUS REGULATION OF SINUS (SINOATRIAL) NODE IN TYPE 1 AND 2 DIABETES MELLITUS].

The aim of this work was to study peripheral vegetative regulation of pacemaker activity of the sinus (sinoatrial) node (SN) by high resolution analysis of cardiac rhythm variability (CRV) in patients with type 1 and 2 diabetes mellitus (DM). All CRV waves in the temporal and spectral regions were shown to be reduced. Regulatory effects of SN were pathologically distributed as appears from the increase of inefficient sympatho-metabolic influence due to the decrease of sympatho-parasympathetic one. Such change and redistribution of effects of regulatory SN factors are the predictors of cardiovascular disorders associated with DM1 and DM2. The low-amplitude CRV fluctuations of certain period and frequency suggest their pathogenetic relationship with DM decompensation. They differed from normal parasympathetic lengthening of a single RR-interval due to the high speed of pulse passage along parasympathetic fibers. It is supposed that these waves with periods 2.33. ± 2.35 and 2.3 ± 2.1 s and spectral density peaks 0.23 ± 0.045 and 0.24 ± 0.16 Hz showing average and moderate correlation with clinical and laboratory data (r = 0.543 ± 0.028 in DM1 and 0.388 ± 0.034 in DM2) are markers of diabetic endotoxicosis.

[SPREADING OF TISSUE SPHEROIDS FROM PRIMARY HUMAN FIBROBLASTS ON THE SURFACE OF MICROFIBROUS ELECTROSPUN POLYURETHANE MATRIX (A scanning electron microscopic study)].

Tissue spheroids biofabricated from primary human fibroblasts using non-adhesive agarose forms, were placed by 3D bioprinter on the surface of microfibrous electrospun matrix. It was demonstrated that tissue spheroids attached to the surface of matrix during several hours and then gradually spread for several days which indicates high level of biocompatibiity of electrospun microfibrous polyurethane matrix. During this activity, human fibroblasts used processes of leading cell borders for initial step of attachment to matrix filaments. Tissue constructions formed during spreading of tissue spheroids on the surface of electrospun microfibrous polyurethane matrix seem to be a perspective technology platform for development of new methods of biofabrication and 3D bioprinting.

Terahertz emission from a metallic surface induced by a femtosecond optic pulse.

Results of experimental and theoretical investigations on generation of terahertz radiation at the interaction of femtosecond laser pulses with a metal surface are presented. Investigations are performed with the laser pulse intensities higher compared with that used in papers [Opt. Lett.29, 2674 (2004); Opt. Lett.30, 1402 (2005)]. The most effective generation is observed for p-polarized optical pulses with incidence angles in the range 5°-10° (from the surface), depending on the kind of metal. For the copper, the exponential growth of terahertz pulse energy with the increase of optical pulse energy was registered. Theoretical interpretation for some of the experimental results is proposed based on the model of free electrons in metal.

[Dysregulation of the sinoatrial node of the heart in patients with coronary heart disease during coronary artery bypass surgery].

Results of estimation of variability of cardiac rhythms in patients with coronary heart disease during coronary artery bypass surgery are presented. The aim of the study was to search for innovative methods for the assessment of the patients' conditions as a criterion for their rational choice for cardiosurgical intervention to enable adequate anesthesiological support and postoperative follow-up. We revealed additional characteristics of cardiac rhythm variability facilitating such choice and predictors of the risk of life-threatening heart arrhythmias. It is shown that high-resolution analysis of cardiac rhythms allows such peculiarities of dynamics of patient's conditions to be revealed that can not be exposed by the existing standard methods.

[Analysis of cardiac rhythm variability in patients with sinoatrial node dysfunction].

The study was designed to elucidate the wave structure of heart rhythm variability (HRV) for the assessment of vegetative regulation of pacemaker activity of the sinoatrial node in 362 patients with coronary heart disease. The results were compared with the data of routine cardiologic examination. Sinus node dysfunction and weakness were shown to be accompanied by differential autonomous dysregulations that may be used as additional symptoms for the diagnosis of arrhythmias. Precision analysis of HRV permits to evaluate the arrhythmogenic events behind vegetative regulation of the sinus node, hemodynamic significance of arrhythmic episodes, and dependence of sinoatrial blockade on the degree of autonomous dysregulation. Autonomous cardioneuropathy syndrome is distinguished, its association with necrobiotic changes in the sinus node is demonstrated by electron microscopy.

Anisotropic effects of terahertz emission from laser sparks in air.

Strong terahertz (THz) radiation can be generated by intense femtosecond laser pulses propagating in air. The excitation of transient current induced in the wake just behind the laser pulse is studied in detail using numerical simulations on the basis of Maxwell's equations for THz-band fields and hydrodynamic model for the plasma motion. It is shown that the thermal effects, anisotropic in character in the case of linear polarized laser field, can explain observed quadrupole-type THz radiation pattern in the experiment performed by Akhmedzhanov [Radiophys. Quantum Electron. 52, 482 (2009)]. Taking into account the transverse structure of the plasma filament, our numerical code enables us to calculate the spatial distribution and temporal evolution of terahertz electron current, its spectrum, and angular emission pattern. It is shown that an expansion of full fields in terms of azimuthal modes is a useful tool for research of THz generation in many situations of practical interest.

[Sinus rhythm variability in bronchial asthma].

The subjects, 265 patients with bronchial asthma (BA) patients (mean age: 41.92 +/- 1.36 yr), were examined using spirometry, peak-flowmetry, body plethysmography, EchoCG, and bronchoscopy with biopsy and histologic study. A high-resolution method--rhythmocardiography with temporal statistical and spectral analysis of sinus rhythm variability at rest and at directed testing using hardware and software complex KAP-RK-01-Micor (Chelyabinsk)--was applied. The patients with BA displayed sinus node dysregulation, insufficient vegetative providence, significant depression of peripheral sympathico-parasympathetic regulation in general, intensification of humoral-and-metabolic influence on pacemaker cells in the sinus node, and the forming of a pathophysiological pattern of response to stimuli during tests.

[Calcium as a regulator of intracellular processes in actinomycetes: a review].

Data on the effects of calcium ions (Ca2+) on processes of morphological and physiological differentiation in cultures of actinomycetes have been reviewed, with emphasis on representatives of the genus Streptomyces. Evidence accumulated thus far, of the regulatory role of serine-threonine protein kinases in the differentiation and of the possible involvement of Ca2+-dependent protein kinases in secondary metabolism (including antibiotic biosynthesis) are analyzed. The possibility that regulatory elements of apoptosis (including Ca2+-dependent) function in actinomycetes is discussed. A hypothesis is advanced, according to which determinants of antibiotic resistance play a key role in the network of signal transduction systems of actinomycetes.

[Antioxidant effect on the growth of Saccharopolyspora erythraea and biosynthesis of erythromycins].

Oxidative stress in the mycelium of submerged culture of S. erythraea, an organism producing erythromycins, was observed. The stress could be eliminated by addition of antioxidants, such as butyloxyanisole, alpha-tocopherol, cytochrome C to the culture. In the presence of the antioxidants the mycelium lysis decreased, the level of the decrease being higher in the medium preferably containing carbohydrates vs. the medium mainly containing lipids (soybean oil). The antioxidants had no specific effect on the biosynthesis of erythromycins.

[Biogenesis and regulation of biosynthesis of erythromycins in Saccharopolyspora erythraea: a review]. / Biogenez i reguliatsiia biosinteza éritromitsinov u Saccharopolyspora erythraea.

Data on the structure and stages of biosynthesis of erythromycins, relating to (1) successive addition of L-mycarose and D-desosamine to the lactones erythronolide B and mycarosyl-erythronolide B, respectively, and (2) biotransformation of erythromycin D to erythromycin A, are presented. Pathways of biosynthesis of L-mycarose, D-desosamine, and methylmalonyl-CoA and methylpropionyl-CoA precursors of erythronolide B are reviewed, along with the properties of genes coding the enzymes involved. Possible mechanisms of biochemical and gene regulation of erythromycin biosynthesis in Saccharopolyspora erythraea are discussed, including the role of factors ensuring predominant formation of the target product, erythromycin A.

[Dependence of the composition of the avermectin complex of Streptomyces avermitilis on glucose content of the growth medium]. / Zavisimost' sostava avermektinovogo kompleksa Streptomyces avermitilis ot soderzhaniia gliukozy v srede.

The effects of glucose concentration in the medium and O-methyl-L-threonine resistance on the ratio of components of the avermectin complex produced by Streptomyces avermitilis have been studied. Glucose deficiency increases the ratio of components A and a, while decreasing that of components 1 in the complex. A mutation that renders the microorganisms resistant to O-methyl-L-threonine (an analog of isoleucine) increases the ratio of components a, while decreasing that of components 1 in the complex. The distribution of a and b in fractions 1 and 2 remains constant: the values of the ratio a/b in the fractions amount, respectively, to 1:1 and 2:1. The relation of the variations in the composition of the avermectin complex to changes in the carbohydrate metabolism of the producer stain, underlain by availability of the source of carbon, is discussed.

Regaining chondrocyte phenotype in thermosensitive gel culture.

Chondrocyte tissue engineering continues to be a challenging problem. When chondrocytes are duplicated in vitro, it is imperative to obtain an adequate number of cells of optimal phenotype. A temperature-sensitive polymer gel, a copolymer of poly(N-isopropylacrylamide) and acrylic acid (PNiPAAm-co-Aac), has the ability of gelling at 37 degrees C (the lower critical solution temperature, LCST) or above and liquefying below that temperature (Vernon and Gutowska, Macromol. Symp. 1996;109:155-167). The hypothesis of this study was that chondrocytes could (1) duplicate in the copolymer gel; (2) regain their chondrocyte phenotype; and (3) be easily recovered from the gel by simply lowering the temperature below 37 degrees C. Chondrocytes from adult rabbit scapular cartilage were harvested and cultured in a monolayer culture until confluency (approximately 2 weeks). Next, the cells were harvested and seeded into the copolymer gel and cultured for 2-4 weeks. The phenotype of the cultured cells was then characterized. Two groups of control cultures, monolayer and agarose gel, were used to compare their ability to maintain chondrocyte phenotype. The results showed that chondrocytes isolated from rabbit scapula can re-express chondrocyte phenotype in agarose culture and polymer gel culture but not in monolayer culture. Also, cultured chondrocytes can be easily recovered from polymer gel culture by simply lowering the temperature. This new in vitro method of chondrocyte culture is recommended for chondrocyte propagation and regaining chondrocyte phenotype before cell seeding or transplantation.