Industrial toxicology of metals of the platinum group

Metals of the platinum group have found important application in technology and industry. Compounds of these metals display a broad spectrum of toxic effects on the organism. In persons dealing with them in the production, they induce allergic occupational diseases of the respiratory passages, dermatoses, affections of the eyes. Their resorptive chronic effect in experiment is characterized by reduction in the body mass of the animals and the content of haemoglobin in the blood, by disturbances of the protein-synthesizing function of the liver, decreased cholinesterase activity in the blood, impaired carbohydrate and lipid metabolism, reduced concentrating capacity of the liver, development of glomerulonephritis. Platinum and platinoids irritate mucous membranes and skin. They penetrate the organism through intact skin. Data on the distribution of the metals in the organs and on their elimination from the organism are reported. Toxicity of the metals of the platinum group is correlated with valence of the compounds and with electron structure. MAC for milling and condensation aerosols of poorly soluble compounds (metal and its oxides) are recommended at 0.1 mg/m3. For aerosols of all soluble compounds of platinum and platinoids, MAC of 0.001 mg/m3 are recommended.     

Anaerobic Microbial Degradation of Polypropylene and Polyvinyl Chloride Samples

Microbiology - Resistance to biodegradation, which is among the most advantageous features of synthetic polymers, is also the reason for their accumulation in the environment and therefore...     

Genetic and morphological divergence between Littorina fabalis ecotypes in Northern Europe

Low dispersal marine intertidal species facing strong divergent selective pressures associated with steep environmental gradients have a great potential to inform us about local adaptation and reproductive isolation. Among these, gastropods of the genus Littorina offer a unique system to study parallel phenotypic divergence resulting from adaptation to different habitats related with wave exposure. In this study, we focused on two Littorina fabalis ecotypes from Northern European shores and compared patterns of habitat‐related phenotypic and genetic divergence across three different geographic levels (local, regional and global). Geometric morphometric analyses revealed that individuals from habitats moderately exposed to waves usually present a larger shell size with a wider aperture than those from sheltered habitats. The phenotypic clustering of L. fabalis by habitat across most locations (mainly in terms of shell size) support an important role of ecology in morphological divergence. A genome scan based on amplified fragment length polymorphisms (AFLPs) revealed a heterogeneous pattern of differentiation across the genome between populations from the two different habitats, suggesting ecotype divergence in the presence of gene flow. The contrasting patterns of genetic structure between nonoutlier and outlier loci, and the decreased sharing of outlier loci with geographic distance among locations are compatible with parallel evolution of phenotypic divergence, with an important contribution of gene flow and/or ancestral variation. In the future, model‐based inference studies based on sequence data across the entire genome will help unravelling these evolutionary hypotheses, improving our knowledge about adaptation and its influence on diversification within the marine realm.     

Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes

Both classical and recent studies suggest that chromosomal inversion polymorphisms are important in adaptation and speciation. However, biases in discovery and reporting of inversions make it difficult to assess their prevalence and biological importance. Here, we use an approach based on linkage disequilibrium among markers genotyped for samples collected across a transect between contrasting habitats to detect chromosomal rearrangements de novo. We report 17 polymorphic rearrangements in a single locality for the coastal marine snail, Littorina saxatilis. Patterns of diversity in the field and of recombination in controlled crosses provide strong evidence that at least the majority of these rearrangements are inversions. Most show clinal changes in frequency between habitats, suggestive of divergent selection, but only one appears to be fixed for different arrangements in the two habitats. Consistent with widespread evidence for balancing selection on inversion polymorphisms, we argue that a combination of heterosis and divergent selection can explain the observed patterns and should be considered in other systems spanning environmental gradients.     

Neuropeptide Organization of the Nociceptive and Antinociceptive Brain Systems in the Cat

Using radioimmune techniques, we studied in detail the concentrations of -endorphin (-En), met- and leu-enkephalins (mE and lE, respectively), and substance P (SP) in a number of structures of the brainstem and forebrain of the cat. According to the proposed concept, these structures comprise the noci- and antinociceptive brain systems (NS and ANS). The above indices were measured in intact animals and in animals after nociceptive electrocutaneous stimulation (NECS) of the limb, stimulation of the ventrolateral zone of the midbrain central gray (vl SGC, a nociceptive midbrain structure), stimulation of the dorsolateral part of the above region and dorsal raphe nucleus (dl SGC and Rd, antinociceptive midbrain structures), and after combined stimulations (NECS preceded by conditioning stimulation of one of the above midbrain zones). We found that in the norm maximum SP concentrations were observed in the NS structures, while those of -En and mE were the highest in the hypothalamic nuclei belonging to the ANS and in its midbrain centers (dl SGC and Rd). Nociceptive ECS, stimulations of the studied midbrain zones, and combinations of these stimulations could result in specific and, in some cases, very significant (by an order of magnitude and more) shifts in the concentrations of the mentioned neuropeptides in the studied set of the central structures. After NECS and its combination with vl SGC stimulation, SP concentrations in the NS structures considerably increased, while -En and mE concentrations in the ANS components dropped. Stimulations of the dl SGC and Rd were accompanied by increases in the mE and -En levels and simultaneous drops in the SP concentrations in the ANS components; reciprocate shifts were observed within the NS. Changes in the lE level, which were related to the influences used, were less specific and mostly appeared as increases in this index in the structures of both the NS and ANS. Combinations of NECS with conditioning stimulations of the vl SGC, dl SGC, or Rd demonstrated that the latter exert significant modulatory effects on the NECS-induced shifts in the concentrations of the studied neuropeptides. Considering the obtained data, a hypothetical scheme of neuropeptide organization of the cerebral NS and ANS has been proposed. In the examined brain structures, there are neuronal populations belonging to the two main neurochemical systems. One of them is SP-ergic, while another consists of mE- and -En-ergic neurons; these systems are in antagonistic relations. Changes in the levels of mE and -En always induce the attended opposite shifts in the SP levels, and vice versa. The lE-ergic neuronal populations, which co-exist with the above neurochemical systems, are relatively nonspecifically activated by either (noci- and antinociceptive) drives, but, according to the pattern of its responses, the lE-ergic system is closer to the SP-ergic one. It is supposed that pain signals, when coming to the vl SGC, activate SP- and lE-ergic neuronal populations; later on, the posterior and lateral hypothalamic nuclei and preoptic region are involved in the transmission of the above signals. When released by the corresponding neuronal populations in the vl SGC, lE activates the key ANS structures (dl SGC and Rd), and the latter, in turn, activate other components of this system, which form its ascending compartment (ventromedial, dorsomedial, and paraventricular hypothalamic nuclei, septum, basolateral amygdala, hippocampal fields 3 and 4, and cingular cortex). In the ANS,-En and mE function as transmitters.     

Stress in Morphine-Addicted Rats: Antistressor Properties of Comenic Acid

In chronic experiments carried out on 128 rats we demonstrated that the withdrawal syndrome revealed in morphine-addicted animals is combined with the development of stress. This was reflected in an increase in the total duration of grooming behavior and in changes in its temporal pattern. In morphine-addicted animals, only the initial and final phases of the seven successive grooming phases remained clearly pronounced, whereas intermediate stages were lost. A recycling of the initial grooming stage, which could result in self-inflicted damage to the skin, was observed. Under conditions of complete discontinuation of morphine, disturbances of grooming were even intensified, and during 18 days after discontinuation of the drug such disturbances gradually disappeared. Injections of comenic acid against the background of discontinuation of morphine significantly accelerated the process of normalization of both the duration and pattern of grooming (9 days after discontinuation of the drug). In intact rats, comenic acid did not induce noticeable disturbances of grooming. We conclude that comenic acid possesses antistressor properties under conditions of the withdrawal syndrome.     

Structural diversity of nucleoside phosphonic acids as a key factor in the discovery of potent inhibitors of rat T-cell lymphoma thymidine phosphorylase

Structurally diverse, sugar-modified, thymine-containing nucleoside phosphonic acids were evaluated for their ability to inhibit thymidine phosphorylase (TP, EC 2.4.2.4) purified from spontaneous T-cell lymphomas of an inbred Sprague-Dawley rat strain. From a large set of tested compounds, among them a number of pyrrolidine-based derivatives, 10 nucleotide analogues with IC₅₀ values below 1 μM were selected. Out of them, four compounds strongly inhibited the enzyme with IC₅₀ values lying in a range of 11–45 nM. These most potent compounds might be bi-substrate analogues.     

Oncolytic Viruses in the Therapy of Lymphoproliferative Diseases

Molecular Biology - Cancer is a leading causes of death. Despite significant success in the treatment of lymphatic system tumors, the problems of relapse, drug resistance and effectiveness of...     

Glacial history of the North Atlantic marine snail, Littorina saxatilis, inferred from distribution of mitochondrial DNA lineages

The North Atlantic intertidal gastropod, Littorina saxatilis (Olivi, 1792), exhibits extreme morphological variation between and within geographic regions and has become a model for studies of local adaptation; yet a comprehensive analysis of the species' phylogeography is lacking. Here, we examine phylogeographic patterns of the species' populations in the North Atlantic and one remote Mediterranean population using sequence variation in a fragment of the mitochondrial cytochrome b gene (607 bp). We found that, as opposed to many other rocky intertidal species, L. saxatilis has likely had a long and continuous history in the Northwest Atlantic, including survival during the last glacial maximum (LGM), possibly in two refugia. In the Northeast Atlantic, several areas likely harboured refugial populations that recolonized different parts of this region after glacial retreat, resulting in strong population structure. However, the outlying monomorphic Venetian population is likely a recent anthropogenic introduction from northern Europe and not a remnant of an earlier wider distribution in the Mediterranean Sea. Overall, our detailed phylogeography of L. saxatilis adds an important piece to the understanding of Pleistocene history in North Atlantic marine biota as well as being the first study to describe the species' evolutionary history in its natural range. The latter contribution is noteworthy because the snail has recently become an important model species for understanding evolutionary processes of speciation; thus our work provides integral information for such endeavours.     

Using of 4-thiouridine and 4-thiothymidine for pyrimidine nucleoside phosphorylase studing

4-Thiouridine and 4-thiothymidine were developed as efficient substrates for spectrophotometric determination of uridine phosphorylase and thymidine phosphorylase activity. 4-Thiouridine has maximum absorbance at 330 nm (pH 7.5). The change in extinction coefficient for 4-thiouridine/4-thiouracil, deltaepsilon is 3000 M(-1) x cm(-1). It appeared that 4-thiouridine is a good substrate for uridine phosphorylase with Michaelis-Menten constant 130 microM and kcat 49 s(-1). In the case of 4-thiothymidine/4-thiothymine deltaepsilon is even larger: 5000 M(-1) x cm(-1) at 336 nm.