An Electroacoustic Analysis for Determining the Effect of Amoxicillin on Microbial Cells

The probability of determining the effects of amoxicillin, which is one of β-lactam antibiotics, on microbial cells of Escherichia coli by the electroacoustic analysis method was shown for the first time. A piezoelectric resonator with a lateral electric field with a 1-mL liquid container was used as a biological sensor. It has been established that in the presence of amoxicillin the frequency dependence of the real and imaginary parts of the electrical impedance of a resonator loaded with a suspension of sensitive cells differs significantly from those of the resonator with a control of a microbial cell suspension without an antibiotic. When the resonator is loaded with the amoxicillin-resistant cell suspension, these dependencies are virtually the same. These results open prospects for the use of electroacoustic analysis methods to register the effect of β-lactam antibiotics on microbial cells and evaluate their antibacterial activity.     

Application of the method of electro-acoustical analysis for the detection of bacteriophages in a liquid phase

The possibility of the application of electro-acoustic analysis for the detection of bacteriophages was demonstrated for the first time based on the example of the interaction of the FA1-Sp59b bacteriophage with bacterial cells of the strain Azospirillum lipoferum Sp59b. Piezoelectric cross-field resonators with a 1-mL chamber for analyzed liquid were used as the biological sensor. It was revealed that the dependences of the real and imaginary parts of the electrical impedance of the resonator loaded with a suspension of viruses and microbial cells on the frequency was significantly different from those dependences of the resonator that contained a control cell suspension without the virus. It was shown that detection of the FA1-Sp59b bacteriophage using microbial cells was possible with both extraneous viral particles and extraneous microbial cells. The proposed method allows one to accurately determine the type of identified virus after a 5-minute interaction with indicating bacterial culture. As well, the minimum concentration of viruses is five virus particles per cell. These results as a whole demonstrate the possibility of detecting specific interactions of bacteriophages with microbial cells and provide a basis for the development of a biological sensor for the quantitative detection of viruses directly in the liquid phase.     

Status epilepticus impairs synaptic plasticity in rat hippocampus and is followed by changes in expression of NMDA receptors

Cognitive deficits and memory loss are frequent in patients with temporal lobe epilepsy. Persistent changes in synaptic efficacy are considered as a cellular substrate underlying memory processes. Electrophysiological studies have shown that the properties of short-term and long-term synaptic plasticity in the cortex and hippocampus may undergo substantial changes after seizures. However, the neural mechanisms responsible for these changes are not clear. In this study, we investigated the properties of short-term and long-term synaptic plasticity in rat hippocampal slices 24 h after pentylenetetrazole (PTZ)-induced status epilepticus. We found that the induction of long-term potentiation (LTP) in CA1 pyramidal cells is reduced compared to the control, while short-term facilitation is increased. The experimental results do not support the hypothesis that status epilepticus leads to background potentiation of hippocampal synapses and further LTP induction becomes weaker due to occlusion, as the dependence of synaptic responses on the strength of input stimulation was not different in the control and experimental animals. The decrease in LTP can be caused by impairment of molecular mechanisms of neuronal plasticity, including those associated with NMDA receptors and/or changes in their subunit composition. Realtime PCR demonstrated significant increases in the expression of GluN1 and GluN2A subunits 3 h after PTZ-induced status epilepticus. The overexpression of obligate GluN1 subunit suggests an increase in the total number of NMDA receptors in the hippocampus. A 3-fold increase in the expression of the GluN2B subunit observed 24 h after PTZ-induced status epilepticus might be indicative of an increase in the proportion of GluN2B-containing NMDA receptors. Increased expression of the GluN2B subunit may be a cause for reducing the magnitude of LTP at hippocampal synapses after status epilepticus.     

Historical biogeography of the Yucatan Peninsula,Mexico: a perspective from ferns (Monilophyta) and lycopods (Lycophyta)

Based on known data sets and maximum entropy distribution data of fern and lycopod species registered in the Yucatán Peninsula, track and parsimony analyses were undertaken to evaluate the contribution of these groups to the establishment of biogeographical relationships of the peninsula with other areas. The resulting generalized tracks clearly agree with the geological origin of the peninsula and the previously recognized relationship with the Greater Antilles is not supported for ferns and lycopods. Instead, a Central American generalized track connects the Yucatán Peninsula with south‐eastern México and Central America. Floristically, the peninsula harbours 66 species of ferns and lycopods. Seven are registered for the first time in the Yucatán Peninsula and one is a new species for México. These species do not follow the latitudinal pattern expected if ecological factors, such as humidity and rainfall, were the most important in determining their distributions. Groups of areas recognized with parsimony analysis of endemicity could not be defined as provinces as a result of the lack of endemic species. Nevertheless, a regionalization scheme based on maximum entropy distribution data and supported by track analyses is proposed. Two separate districts are recognized within the Yucatán Peninsula: arid/dry Yucatán in the north and El Petén (humid) in the south. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 775–786.     

Study of soft X-ray emission from Z-pinches with a complex atomic composition

Results are presented from experimental studies of Z-pinches produced by implosion of aluminum and tungsten cylindrical wire arrays in the Angara-5-1 facility. The electron temperature T _e and density n _e of the high-temperature pinch plasma have been determined by analyzing line emission from multicharged ions. For the same mass and radius of the array and the same number of wires in it, the intensity of line emission of H- and He-like Al ions from an imploded Al + W wire array containing even a small amount of tungsten (7 wt %) is one order of magnitude lower than that from an Al array. As the W content increases, the total soft X-ray (SXR) yield increases, while the duration of the SXR pulse decreases. For the 30% W content in the array, the power and duration of the SXR pulse are nearly the same as those recorded during the implosion of a W array with the same linear mass and radius and the same number of wires. Results are also presented from experiments with nested wire arrays in which the outer and inner shells were made of Al and W wires, respectively. It is found that, in this case, the effect of tungsten on the line emission of aluminum is much weaker than that in experiments with arrays in which tungsten and aluminum wires were placed in the same shell, even if the mass of the inner (tungsten) shell was larger than that of the outer (aluminum) one. At the same time, the inner W shell plays a significant role in the implosion dynamics of a nested wire array, reducing the duration of the SXR pulse and increasing the SXR power.     

Immunophenotypic peculiarities of mobilized stem (CD34+) cells in blood from patients with severe spinal cord injury

Immunophenotype of mobilized stem blood cells (CD34+) was studied in 29 patients with late post-traumatic spinal lesions. The CD34+ cells demonstrated different levels of expression of CD45, CD38, monomorphic determinants HLA-DR and gp130 epitopes. Most patients presented with a CD34+ cell fraction with no or low expression of common leukocytic antigen CD45. Only 2 patients had greater than 15 percent of HLA-DR-CD38- cells in the CD34+ fraction. A common transducer molecule of interleukin-6 family cytokines gp130 was expressed on stem (CD34+) cells in all the cases, 26 percent of the patients had an activated gp130 phenotype, i.e. a combination of C7+ and A1- epitopes.     

Presynaptic serotonergic modulation of spontaneous and miniature synaptic activity in frog lumbar motoneurons

The effects of serotonin (5-HT, 30 μM) on spontaneous and miniature synaptic activity in lumbar motoneurons from the isolated Rana ridibunda spinal cord were investigated using intracellular recording. 5-HT increased the frequency of spontaneous (sPSPs) and miniature postsynaptic potentials (mPSPs). The effect of 5-HT on different subpopulations of mPSPs was multidirectional: it increased the frequency of glutamatergic excitatory mPSPs by 18% and decreased the frequency of glycinergic inhibitory mPSPs by 28%, but had no effect on the frequency of GABAergic inhibitory mPSPs. The amplitude and kinetic parameters of any subpopulation of mPSPs did not change. The data obtained show that 5-HT regulates the probability of glutamate and glycine release from the presynaptic terminals ending at frog spinal motoneurons. 5-HT shifts the balance between synaptic excitation and inhibition in the spinal neural network toward excitation. Thus, 5-HT participates in control of motor output and provides its facilitation.     

Multinuclear blue copper-proteins: the evolutionary design

The review presents both our own and literature data on studies of pathways of evolution of the so-called multinuclear blue copper-proteins (MBCP) that have the domain organization. The MBCP are widely spread in living nature, they have been revealed in cells of archei, bacteria, and eukaryotes. The MBCP composition includes the copper-proteins such different by their properties as oxidases, reductase, blood coagulation factors V and VIII. Most likely, MBCP have been originated from a low-molecular protein-precursor similar topologically with the blue electron-transporting protein of the cupredoxin type, as a result of action of various evolutionary mechanisms: amplification of genes, formation of protein structures by different combinations of domains, a change of size of domains, the segment elongation at the expense of the activational domain, formation and loss of copper-binding centers, variation of amino acid ligands in such centers, the appearance of centers of binding of other proteins, glycosylation, etc.