Acoustic detection of absorption of millimeter-band electromagnetic waves in biological objects

Principles of photoacoustic spectroscopy were applied to elaborate a new method for controlling millimeter electromagnetic waves absorption in biological objects. The method was used in investigations of frequency dependence of millimeter wave power absorption in vitro and in vivo in the commonly used experimental irradiation systems.     

Biological structures as photonic objects

Samples of the material of mollusks bowls, peacock wing elements, and human horn skin have been investigated using the methods of spectroscopy, atomic-force microscopy, X-ray diffraction analysis, and thermoconductance. Ordered superstructures were revealed in these objects. Evidence for effective interactions of both electromagnetic and electronic waves with these structures was obtained. It was shown that the interaction with electromagnetic waves reveals photonic properties and the interaction with electronic waves, the semiconducting properties of biological objects.     

A method for improving measuring accuracy in multi-channel impedance spectroscopy (MIS)]

The use of impedance spectroscopy as a diagnostic tool for the investigation of biological objects involves the consideration of numerous parameters impacting on measuring accuracy. This paper describes a calibration method for multichannel instruments that reduces the non-inconsiderable influence of frequency response variations between the channels, thus significantly increasing measuring accuracy. The method is tested in a recently developed, high-resolution, multi-channel bio-impedance analyser. Reduction of the measuring error is demonstrated, and the magnitude and phase resolution is quantified. The advantage of this method lies in its applicability to existing systems. Furthermore, an additional calibration impedance is not needed.     

Structure elucidation of dimeric transmembrane domains of bitopic proteins

The interaction between transmembrane helices is of a great interest because it directly determines biological activity of a membrane protein. Either destroying or enhancing such interactions can result in many diseases related to dysfunction of different tissues in human body. One much studied form of membrane proteins known as bitopic protein is a dimer containing two membrane-spanning helices associating laterally. Establishing structure-function relationship as well as rational design of new types of drugs targeting membrane proteins requires precise structural information about this class of objects. At present time, to investigate spatial structure and internal dynamics of such transmembrane helical dimers, several strategies were developed based mainly on a combination of NMR spectroscopy, optical spectroscopy, protein engineering and molecular modeling. These approaches were successfully applied to homo- and heterodimeric transmembrane fragments of several bitopic proteins, which play important roles in normal and in pathological conditions of human organism.     

Fungal biosorption of silver particles on 20th-century photographic documents

Microbial deterioration is a common problem in photographic collections and is considered a major cause of loss of documents. However, few studies so far have been addressed to biological damage on these materials. Several species of naturally occurring fungi can cause infections on the gelatin-silver emulsion of both positive and negative photographic material, producing defacement and loss of mechanical and aesthetical properties of the objects. In this study a particular phenomenon, spontaneously caused by fungi on 20th-century photographic films and positive supports, was documented by means of variable pressure scanning electron microscopy (VP-SEM) combined with electronic dispersion spectroscopy (EDS). This technique allowed the observation of entire, unaltered films without metallisation thus with a not invasive approach. The ability of some fungi to alter the distribution of silver crystals in the gelatin emulsion was described thanks to a backscattered electrons detector that showed differences in the atomic number of the visualised objects, giving rise to an appreciable contrast in case of different chemical composition.     

Isotopic effects of low concentration of deuterium in water on biological systems

Isotopic effects of deuterium in water are studied in a broad range of concentrations on a number of biological objects of different organization levels. The results obtained show that biological objects are sensitive to variations of isotope composition in water. A decrease or increase in deuterium concentrations in water may cause activation or inhibition of biological functions. The values of biological isotopic effects of low deuterium concentration may even be higher than those of high deuterium concentration. No regularity in response for all the objects studied failed to find out in a range of deuterium concentration in water from 4 ppm to 1%.     

Teaching electron diffraction and imaging of macromolecules.

Electron microscopic analysis can be used to determine the three-dimensional structures of macromolecules at resolutions ranging between 3 and 30 A. It differs from nuclear magnetic resonance spectroscopy or x-ray crystallography in that it allows an object's Coulomb potential functions to be determined directly from images and can be used to study relatively complex macromolecular assemblies in a crystalline or noncrystalline state. Electron imaging already has provided valuable structural information about various biological systems, including membrane proteins, protein-nucleic acid complexes, contractile and motile protein assemblies, viruses, and transport complexes for ions or macromolecules. This article, organized as a series of lectures, presents the biophysical principles of three-dimensional analysis of objects possessing different symmetries.     

Measurement of Thermal Effects of Doppler Ultrasound: An In Vitro Study

Objective

Ultrasound is considered a safe imaging modality and is routinely applied during early pregnancy. However, reservations are expressed concerning the application of Doppler ultrasound in early pregnancy due to energy emission of the ultrasound probe and its conversion to heat. The objective of this study was to evaluate the thermal effects of emitted Doppler ultrasound of different ultrasound machines and probes by means of temperature increase of in-vitro test-media.

Methods

We investigated the energy-output of 5 vaginal and abdominal probes of 3 ultrasound machines (GE Healthcare, Siemens, Aloka). Two in-vitro test objects were developed at the Center for Medical Physics and Biomedical Engineering, Medical University Vienna (water bath and hydrogel bath). Temperature increase during Doppler ultrasound emission was measured via thermal sensors, which were placed inside the test objects or on the probes’ surface. Each probe was emitting for 5 minutes into the absorbing test object with 3 different TI/MI settings in Spectral Doppler mode.

Results

During water bath test, temperature increase varied between 0.1 and 1.0°C, depending on probe, setting and focus, and was found highest for spectral Doppler mode alone. Maximum temperature increase was found during the surface heating test, where values up to 2.4°C could be measured within 5 minutes of emission.

Conclusions

Activation of Doppler ultrasound in the waterbath model causes a significant increase of temperature within one minute. Thermally induced effects on the embryo cannot be excluded when using Doppler ultrasound in early pregnancy.     

Assessment of skin flaps using optically based methods for measuring blood flow and oxygenation

The objective of this study was to compare two noninvasive techniques, laser Doppler and optical spectroscopy, for monitoring hemodynamic changes in skin flaps. Animal models for assessing these changes in microvascular free flaps and pedicle flaps were investigated. A 2 x 3-cm free flap model based on the epigastric vein-artery pair and a reversed MacFarlane 3 x 10-cm pedicle flap model were used in this study. Animals were divided into four groups, with groups 1 (n = 6) and 2 (n = 4) undergoing epigastric free flap surgery and groups 3 (n = 3) and 4 (n = 10) undergoing pedicle flap surgery. Groups 1 and 4 served as controls for each of the flap models. Groups 2 and 3 served as ischemia-reperfusion models. Optical spectroscopy provides a measure of hemoglobin oxygen saturation and blood volume, and the laser Doppler method measures blood flow. Optical spectroscopy proved to be consistently more reliable in detecting problems with arterial in flow compared with laser Doppler assessments. When spectroscopy was used in an imaging configuration, oxygen saturation images of the entire flap were generated, thus creating a visual picture of global flap health. In both single-point and imaging modes the technique was sensitive to vessel manipulation, with the immediate post operative images providing an accurate prediction of eventual outcome. This series of skin flap studies suggests a potential role for optical spectroscopy and spectroscopic imaging in the clinical assessment of skin flaps.     

The possible contribution of late pleistocene biota to biodiversity in present permafrost zone

During the last decade a wide range of biological objects, which have preserved their viability for tens and hundreds of thousands of years, was found in the samples of permafrost sediments from North-East Eurasia. Among them are bacteria, fungi, algae, moss spores, seeds of higher plants, protists. Along with physiological mechanisms of cryoconservation and constant low temperature of great importance for long-term preservation of biological objects in permafrost layers are ways of burying the organisms and conditions that prevail before the transition of sediments to the permafrost state. The analysis of viability showed by preserved biological objects gives reasons to suppose that some representatives of Pleistocene biota buried in permafrost thickness may contribute to the biodiversity of present cryolite zone.     

Biophotonics methods for functional monitoring of complications of diabetes mellitus

The prevalence of diabetes complications is a significant public health problem with a considerable economic cost. Thus, the timely diagnosis of complications and prevention of their development will contribute to increasing the length and quality of patient life, and reducing the economic costs of their treatment. This article aims to review the current state‐of‐the‐art biophotonics technologies used to identify the complications of diabetes mellitus and assess the quality of their treatment. Additionally, these technologies assess the structural and functional properties of biological tissues, and they include capillaroscopy, laser Doppler flowmetry and hyperspectral imaging, laser speckle contrast imaging, diffuse reflectance spectroscopy and imaging, fluorescence spectroscopy and imaging, optical coherence tomography, optoacoustic imaging and confocal microscopy. Recent advances in the field of optical noninvasive diagnosis suggest a wider introduction of biophotonics technologies into clinical practice and, in particular, in diabetes care units.     

Structure elucidation of dimeric transmembrane domains of bitopic proteins

The interaction between transmembrane helices is of great interest because it directly determines biological activity of a membrane protein. Either destroying or enhancing such interactions can result in many diseases related to dysfunction of different tissues in human body. One much studied form of membrane proteins known as bitopic protein is a dimer containing two membrane-spanning helices associating laterally. Establishing structure-function relationship as well as rational design of new types of drugs targeting membrane proteins requires precise structural information about this class of objects. At present time, to investigate spatial structure and internal dynamics of such transmembrane helical dimers, several strategies were developed based mainly on a combination of NMR spectroscopy, optical spectroscopy, protein engineering and molecular modeling. These approaches were successfully applied to homo- and heterodimeric transmembrane fragments of several bitopic proteins, which play important roles in normal and in pathological conditions of human organism.Key words: bitopic proteins, transmembrane domain dimer, spatial structure, dynamics, protein-protein interactions, protein-membrane interactions, molecular modeling, NMR     

Hydrolysable tannins change physicochemical parameters of lipid nano-vesicles and reduce DPPH radical - Experimental studies and quantum chemical analysis

Tannins belong to plant secondary metabolites exhibiting a wide range of biological activity. One of the important aspects of the realization of the biological effects of tannins is the interaction with lipids of cell membranes. In this work we studied the interaction of two hydrolysable tannins: 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG) and 1,2-di-O-galloyl-4,6-valoneoyl-β-d-glucose (T1) which had the same number of both aromatic rings (5) and hydroxyl groups (15) but differing in flexibility due to the presence of valoneoyl group in the T1 molecule with DMPC (dimyristoylphosphatidylcholine) lipid nano-vesicles (liposomes). Tannins-liposomes interactions were investigated using fluorescence spectroscopy, differential scanning calorimetry, laser Doppler velocimetry, dynamic light scattering and Fourier Transform Infra-Red spectroscopy. It was shown that more flexible PGG molecules stronger decreased the microviscosity of the liposomal membranes and increased the values of negative zeta potential in comparison with the more rigid T1. Both compounds diminished the phase transition temperature of DMPC membranes, interacted with liposomes via PO groups of head of phospholipids and their hydrophobic regions. These tannins neutralized DPPH free radicals with the stoichiometry of the reaction equal 1:1.The effects of the studied compounds on liposomes were discussed in relation to tannin quantum chemical parameters calculated by molecular modeling.     

DNA amplification using PCR with abutting primers

Molecular Biology - DNA analysis of ñîmplex biological objects (wastewater, soil, archaeological and forensic samples, etc.) is currently of great interest. DNA of these objects is...     

Possibility of using near infrared irradiation for early cancer diagnosis

Penetration of near infrared radiation (NIR) through biological tissues (human wrist, muscle and skin of hen, muscle of mollusk) was studied. The possibilities of visualizing various objects within biological tissues were examined. It is found that: (a) it is possible to see small objects with millimeter and sub-millimeter dimensions; and (b) by using NIR rays it is possible to distinguish different parts of small homogeneous biological tissues. NIR can be a possible tool in the near future to visualize millimeter size cancerous outgrowths located inside human body cavities. It will enable diagnosis of cancer at an early stage of development.     

A review of projection radiography of plasma and biological objects in X-Pinch radiation

A review of studies on the X-pinch as a radiation source for X-ray projection shadow radiography (XPSR) and X-ray absorption spectroscopy (XAS) is presented. The ultimate capabilities of the techniques and ways of their achievement are considered. XPSR has been successfully used to study high-energy-density plasma objects, in particular, exploding wires and wire arrays. Using XPSR, the internal structure and dynamics of a wire explosion and wire array implosion have been investigated for the first time, which has made it possible to develop an adequate consistent theory of the processes occurring in the wire loads of generators with currents from several units of kiloamperes to a few tens of megamperes. The use of XAS for diagnostics of wire loads has allowed one for the first time to measure the parameters of matter in the wire core and plasma corona of the load. X-ray images of various biological objects have obtained, including those with the use of the phase contrast method. This review is a logical continuation of the review “Х-Pinch” [Plasma Phys. Rep. 41, 319, 493 (2015)], in which the Х-pinch as a physical object was considered.     

Quantitative electron probe X-ray microanalysis of thin objects using an independent mass determination method

Elemental mass fraction determinations on thin biological specimens by quantitative electron probe X-ray microanalysis commonly use a total mass estimation based on registration of X-ray continuum. We have tested whether the accurary of such determinations on individual biological objects can be improved when a densitometric method for mass determination is used. Air-dried femtoliter droplets with dry masses in the order of 10⁻¹⁶ kg were used as model objects. An improvement of over two-fold upon the continuum method could be achieved.