Defective repair of oxidative base lesions by the DNA glycosylase Nth1 associates with multiple telomere defects

Telomeres are chromosome end structures and are essential for maintenance of genome stability. Highly repetitive telomere sequences appear to be susceptible to oxidative stress-induced damage. Oxidation may therefore have a severe impact on telomere integrity and function. A wide spectrum of oxidative pyrimidine-derivatives has been reported, including thymine glycol (Tg), that are primarily removed by a DNA glycosylase, Endonuclease III-like protein 1 (Nth1). Here, we investigate the effect of Nth1 deficiency on telomere integrity in mice. Nth1 null (Nth1(-/-) ) mouse tissues and primary MEFs harbor higher levels of Endonuclease III-sensitive DNA lesions at telomeric repeats, in comparison to a non-telomeric locus. Furthermore, oxidative DNA damage induced by acute exposure to an oxidant is repaired slowly at telomeres in Nth1(-/-) MEFs. Although telomere length is not affected in the hematopoietic tissues of Nth1(-/-) adult mice, telomeres suffer from attrition and increased recombination and DNA damage foci formation in Nth1(-/-) bone marrow cells that are stimulated ex vivo in the presence of 20% oxygen. Nth1 deficiency also enhances telomere fragility in mice. Lastly, in a telomerase null background, Nth1(-/-) bone marrow cells undergo severe telomere loss at some chromosome ends and cell apoptosis upon replicative stress. These results suggest that Nth1 plays an important role in telomere maintenance and base repair against oxidative stress-induced base modifications. The fact that telomerase deficiency can exacerbate telomere shortening in Nth1 deficient mouse cells supports that base excision repair cooperates with telomerase to maintain telomere integrity.Haritha Vallabhaneni, Nathan O'Callaghan, Julia Sidorova, Yie Li

Menadione Suppresses Benzo(a)pyrene-Induced Activation of Cytochromes P450 1A : Insights into a Possible Molecular Mechanism

Oxidative reactions that are catalyzed by cytochromes P450 1A (CYP1A) lead to formation of carcinogenic derivatives of arylamines and polycyclic aromatic hydrocarbons (PAHs), such as the widespread environmental pollutant benzo(a) pyrene (BP). These compounds upregulate CYP1A at the transcriptional level via an arylhydrocarbon receptor (AhR)-dependent signaling pathway. Because of the involvement of AhR-dependent genes in chemically induced carcinogenesis, suppression of this signaling pathway could prevent tumor formation and/or progression. Here we show that menadione (a water-soluble analog of vitamin K-3) inhibits BP-induced expression and enzymatic activity of both CYP1A1 and CYP1A2 in vivo (in the rat liver) and BP-induced activity of CYP1A1 in vitro. Coadministration of BP and menadione reduced DNA-binding activity of AhR and increased DNA-binding activity of transcription factors Oct-1 and CCAAT/enhancer binding protein (C/EBP), which are known to be involved in negative regulation of AhR-dependent genes, in vivo. Expression of another factor involved in downregulation of CYP1A-pAhR repressor (AhRR)-was lower in the liver of the rats treated with BP and menadione, indicating that the inhibitory effect of menadione on CYP1A is not mediated by this protein. Furthermore, menadione was well tolerated by the animals: no signs of acute toxicity were detected by visual examination or by assessment of weight gain dynamics or liver function. Taken together, our results suggest that menadione can be used in further studies on animal models of chemically induced carcinogenesis because menadione may suppress tumor formation and possibly progression.Peer reviewe

Выращивание и характеризация тканеинженерной конструкции из гладкомышечных клеток коронарной артерии сердца человека

Aim. To optimize a bioengineered I-Wire platform to grow tissue-engineered constructs (TCs) derived from coronary artery smooth muscle cells and characterize the mechano-elastic properties of the grown TCs.Materials and methods. A fibrinogen-based cell mixture was pipetted in a casting mold having two parallel titanium anchoring wires inserted in the grooves on opposite ends of the mold to support the TC. The casting mold was 3 mm in depth, 2 mm in width and 12 mm in length. To measure TC deformation, a flexible probe with a diameter of 365 mcm and a length of 42 mm was utilized. The deflection of the probe tip at various tensile forces applied to the TC was recorded using an inverted microscope optical recording system. The elasticity modulus was calculated based on a stretch-stress diagram reconstructed for each TC. The mechano-elastic properties of control TCs and TCs under the influence of isoproterenol (Iso), acetylcholine (ACh), blebbistatin (Bb), and cytochalasin D (Cyto-D) were evaluated. Immunohistochemical staining of smooth muscle α-actin, desmin and the cell nucleuswas implemented for the structural characterization of the TCs.Results. The TCs formed on day 5–6 of incubation. Subsequent measurements during the following 7 days did not reveal significant changes in elasticity. Values of the elastic modulus were 7.4 ± 1.5 kPa on the first day, 7.9 ± 1.4 kPa on the third day, and 7.8 ± 1.9 kPa on the seventh day of culturing after TC formation. Changes in the mechano-elastic properties of the TCs in response to the subsequent application of Bb and Cyto-D had a two-phase pattern, indicating a possibility of determining active and passive elements of the TC elasticity. The application of 1 µM of Iso led to an increase in the value of the elastic modulus from 7.9 ± 1.5 kPa to 10.2 ± 2.1 kPa (p < 0.05, n = 6). ACh did not cause a significant change in elasticity.Conclusion. The system allows quantification of the mechano-elastic properties of TCs in response to pharmacological stimuli and can be useful to model pathological changes in vascular smooth muscle cells.Цель. Оптимизировать биоинженерную платформу I-Wire для выращивания тканеинженерных конструкций (ТК) из гладкомышечных клеток (ГМК) артериальных сосудов и охарактеризовать  механоэластические свойства полученных ТК.Материалы и методы. Клеточную смесь на основе фибрина засевали в канал матрицы из полидиметилоксана  с вставками из титановой проволоки на противоположных концах канала для  горизонтальной поддержки конструкции. Размеры канала: глубина 3 мм, ширина 2 мм и длина 12 мм. Для измерения деформации ТК использовали гибкий зонд диаметром 365 мкм и длиной 42 мм. Отклонение кончика зонда при различной силе растяжения, приложенной к ТК, регистрировали с помощью системы оптической регистрации на основе инвертированного микроскопа. Модуль упругости вычисляли на основе диаграмм растяжения ТК. Были оценены механоэластические свойства конструкций в контроле и под действием изопротеренола (Изо), ацетилхолина (Ацх), блеббистатина (Бб) и цитохалазина Д (Цито-Д). Для структурной характеризации конструкций использовали метод иммуногистохимического окрашивания конструкций на α-актин гладких мышц, десмин и ядра клеток.Результаты. Формирование конструкций происходило на 5–6-й день инкубации. Последующие измерения в течение 7 дней не выявили значительных изменений эластичности. Значения величины модуля упругости конструкций составили 7,4 ± 1,5 кПа в первый день после их формирования, 7,9 ± 1,4 кПа – на 3-й и 7,8 ± 1,9 кПа – на 7-й день культивирования. Изменения механоэластических свойств ТК в ответ на  последовательное применение Бб и Цито-Д имели двухфазный характер, что демонстрирует возможность выделения активного и пассивного элементов эластичности гладкомышечных конструкций. Добавление 1 мкМ Изо приводило к увеличению значения величины модуля упругости с 7,9 ± 1,5 кПа до 10,2 ± 2,1 кПа (p < 0,05, n = 6). Добавление Ацх не вызывало значимого изменения эластичности.Заключение. Представленная система позволяет количественно оценивать механоэластические свойства ТК в ответ на фармакологическое воздействие и может быть полезна в моделировании патологических изменений в ГМК сосудов

Immunoglobulinopathies in patients with angioimmunoblastic T-cell lymphoma

Contex. Angioimmunoblastic T-cell lymphoma (AITL) is a rare form of non-Hodgkins lymphoma, characterized by generalized lymphadenopathy, hepatosplenomegaly and dysproteinemia. Hypergammaglobulinaemia is revealed in 50-83% pts with AITL. However, the characteristics of immunoglobulinopathies observed in AITL are scarce. Objective: The aim of the study was to characterize quantitative and qualitative immunoglobulinopathies in patients with AITL at the onset of the disease. Patients and methods. 55 patients with newly diagnosed AITL were enrolled in the study, the male/female ratio was 30/25; median age was 61 (29-81) years. Diagnosis was based on standard WHO criteria. Immunochemical studies of blood serum included serum protein electrophoresis/immunofixation, nephelometric quantification of total immunoglobulins, serum free light chain assay. Results. Quantitative and qualitative immunoglobulinopathies were determined in 49 (89,1%) of 55 pts. Quantitative immunoglobulinopathies were revealed in 47 (85.5%) of 55 cases, qualitative - in 14 (25,5%). Combination quantitative and qualitative immunoglobulinopathies was observed in 12 (21,8%) of 55 pts. The detected immunoglobulinopathies were divided into 4 groups: polyclonal hypergammaglobulinaemia, hypogammaglobulinaemia, oligoclonal gammapathy, and monoclonal gammapathy. Polyclonal hypergammaglobulinaemia was marked in 41 (74.5%) of 55 pts, elevated level of IgG was determined in 27 (49,15%) of 55 cases, IgM - in 18 (32,7%) and IgA - in 21 (38.2%). Interestingly, polyclonal IgE hypergammaglobulinaemia was detected in 12 (48,0%) of 25 cases of performed studies. Hypogammaglobulinaemia was detected in 8 (14,5%) of 55 cases. Oligoclonal gammapathy was determined in 4 (7.3%) of 55 pts. Monoclonal gammapathy was revealed in 11 (20,0%) of 55 cases. The amount of monoclonal immunoglobulin varied from 2.6 to 14.1 g/l. Monoclonal immunoglobulin Gk was detected in 5 of 11 pts, Gλ - in 2, Mλ - in 2, Mk - in 2. Monoclonal gammapathy was accompanied by polyclonal hypergammaglobulinaemia in 9 of 11 cases, hypogammaglobulinaemia - in 2. Conclusions. Quantitative and qualitative immunoglobulinopathies are observed in most patients at the onset of AITL. Quantitative abnormalities were determined more often than qualitative. Monoclonal gammapathy can be a manifestation of lymphoproliferation and other concomitant disorders. The prognostic value of immunochemical parameters is still unclear and requires dynamic observation and study

Comparative analysis of the chemical composition and size of starch granules in grain between diploid and tetraploid sweetcorn cultivars

Background. Improving the taste and nutritional value of sweetcorn using genetic selection techniques is an important trend. The tetraploid sugary maize cultivar ‘Baksanskaya sakharnaya’ (k-23426) has a number of advantages in terms of taste and marketability over traditional diploid varieties.The purpose of the research was to identify the distinctive biochemical characteristics that affect the taste of this cultivar in comparison with the diploid reference (cv. ‘Rannyaya Lakomka’, с-1775).Materials and methods. The differences in phenotypic traits between diploid (2n) and tetraploid (4n) maize plants were assessed. Infrared spectroscopy was used to study the difference in the biochemical composition of kernels in terms of protein, starch and oil content. Accumulation of metabolites in a dry kernel was studied using gas–liquid chromatography with mass spectrometry.Results. Comparison of the phenotypic traits in 2n and 4n sweetcorn plants showed that 4n had a better ear structure, protein and oil content. Analysis of metabolites showed that quantitative indicators of chemical components changed in kernels of the 4n sweetcorn without changing the qualitative composition. The chemical composition of the metabolites in 4n sweetcorn grain was characterized by an increase in the synthesis of most organic acids and protein amino acids, phosphoric acid, fatty acids, some monosaccharides, phenolic compounds, and phytosterols. A decrease in the content of most polyhydric alcohols, disaccharides, trisaccharides, some monosaccharides, and phenolic compounds was observed. An inhibitory effect of a su2 gene dose on the size of starch granules was found. Conclusion. The studies showed the advantage of the 4n sweetcorn over the 2n one due to its improved ear structure and biochemical composition, which positively affected the taste qualities

First experience of using Brentuximab vedotin and modified program NHL-BFM-90 in the front-line treatment of patient with anaplastic large-cell lymphoma: a case report and a review of literature

Nodal anaplastic ALK-negative large cell lymphoma (nALCL, ALK-) is a Т-cell lymphoma that is characterized by aggressive clinical course and low sensitivity to СНОР (cyclophosphamide, doxorubicin, vincristine, prednisolone) and other chemotherapy regimen. In the article we present a literature review and describe our clinical case of nALCL, ALK-. For the first time a combination of Brentuximab vedotin with modified program NHL-BFM-90 was used as a first-line therapy. As a result of immunochemotherapy a complete antineoplastic effect was obtained. For consolidation of this effect high-dose chemotherapy with following autologous blood stem cell transplantation was performed. The chosen treatment tactics allowed to achieve a complete remission in a medium risk group patient

Impact of Atherosclerosis- and Diabetes-Related Dicarbonyls on Vascular Endothelial Permeability: A Comparative Assessment

Background. Malondialdehyde (MDA), glyoxal (GO), and methylglyoxal (MGO) levels increase in atherosclerosis and diabetes patients. Recent reports demonstrate that GO and MGO cause vascular endothelial barrier dysfunction whereas no evidence is available for MDA. Methods. To compare the effects of MDA, GO, or MGO on endothelial permeability, we used human EA.hy926 endothelial cells as a standard model. To study cortical cytoplasm motility and cytoskeletal organization in endothelial cells, we utilized time-lapse microscopy and fluorescent microscopy. To compare dicarbonyl-modified protein band profiles in these cells, we applied Western blotting with antibodies against MDA- or MGO-labelled proteins. Results. MDA (150–250 μM) irreversibly suppressed the endothelial cell barrier, reduced lamellipodial activity, and prevented intercellular contact formation. The motile deficiency of MDA-challenged cells was accompanied by alterations in microtubule and microfilament organization. These detrimental effects were not observed after GO or MGO (250 μM) administration regardless of confirmed modification of cellular proteins by MGO. Conclusions. Our comparative study demonstrates that MDA is more damaging to the endothelial barrier than GO or MGO. Considering that MDA endogenous levels exceed those of GO or MGO and tend to increase further during lipoperoxidation, it appears important to reduce oxidative stress and, in particular, MDA levels in order to prevent sustained vascular hyperpermeability in atherosclerosis and diabetes patients

Diverging climate trends in Mongolian taiga forests influence growth and regeneration of Larix sibirica

Central and semiarid north-eastern Asia was subject to twentieth century warming far above the global average. Since forests of this region occur at their drought limit, they are particularly vulnerable to climate change. We studied the regional variations of temperature and precipitation trends and their effects on tree growth and forest regeneration in Mongolia. Tree-ring series from more than 2,300 trees of Siberian larch (Larix sibirica) collected in four regions of Mongolia’s forest zone were analyzed and related to available weather data. Climate trends underlie a remarkable regional variation leading to contrasting responses of tree growth in taiga forests even within the same mountain system. Within a distance of a few hundred kilometers (140–490 km), areas with recently reduced growth and regeneration of larch alternated with regions where these parameters remained constant or even increased. Reduced productivity could be correlated with increasing summer temperatures and decreasing precipitation; improved growth conditions were found at increasing precipitation, but constant summer temperatures. An effect of increasing winter temperatures on tree-ring width or forest regeneration was not detectable. Since declines of productivity and regeneration are more widespread in the Mongolian taiga than the opposite trend, a net loss of forests is likely to occur in the future, as strong increases in temperature and regionally differing changes in precipitation are predicted for the twenty-first century

The MHD nature of ionospheric wave packets excited by the solar terminator

We obtained the first experimental evidence for the magnetohydrodynamic (MHD) nature of ionospheric medium-scale travelling wave packets (MSTWP). We used data on total electron content (TEC) measurements obtained at the dense Japanese network GPS/GEONET (1220 stations) in 2008-2009. We found that the diurnal, seasonal and spectral MSTWP characteristics are specified by the solar terminator (ST) dynamics. MSTWPs are the chains of narrow-band TEC oscillations with single packet's duration of about 1-2 hours and oscillation periods of 10-20 minutes. Their total duration is about 4--6 hours. The MSTWP spatial structure is characterized by a high degree of anisotropy and coherence at the distance of more than 10 wavelengths. The MSTWP direction of travelling is characterized by a high directivity regardless of seasons. Occurrence rate of daytime MSTWPs is high in winter and during equinoxes. Occurrence rate of nighttime MSTIDs has its peak in summer. These features are consistent with previous MS travelling ionosphere disturbance (TID) statistics obtained from 630-nm airglow imaging observations in Japan. In winter, MSTWPs in the northern hemisphere are observed 3-4 hours after the morning ST passage. In summer, MSTWPs are detected 1.5-2 hours before the evening ST occurrence at the point of observations, at the moment of the evening ST passage in the magneto-conjugate point. Both the high Q-factor of oscillatory system and synchronization of MSTWP occurrence with the solar terminator passage at the point of observations and in the magneto-conjugate area testify the MHD nature of ST-excited MSTWP generation. The obtained results are the first experimental evidence for the hypothesis of the ST-generated ion sound waves.Comment: 12 pages, 3 figure

Mathematical Modelling of DNA Replication Reveals a Trade-off between Coherence of Origin Activation and Robustness against Rereplication

Eukaryotic genomes are duplicated from multiple replication origins exactly once per cell cycle. In Saccharomyces cerevisiae, a complex molecular network has been identified that governs the assembly of the replication machinery. Here we develop a mathematical model that links the dynamics of this network to its performance in terms of rate and coherence of origin activation events, number of activated origins, the resulting distribution of replicon sizes and robustness against DNA rereplication. To parameterize the model, we use measured protein expression data and systematically generate kinetic parameter sets by optimizing the coherence of origin firing. While randomly parameterized networks yield unrealistically slow kinetics of replication initiation, networks with optimized parameters account for the experimentally observed distribution of origin firing times. Efficient inhibition of DNA rereplication emerges as a constraint that limits the rate at which replication can be initiated. In addition to the separation between origin licensing and firing, a time delay between the activation of S phase cyclin-dependent kinase (S-Cdk) and the initiation of DNA replication is required for preventing rereplication. Our analysis suggests that distributive multisite phosphorylation of the S-Cdk targets Sld2 and Sld3 can generate both a robust time delay and contribute to switch-like, coherent activation of replication origins. The proposed catalytic function of the complex formed by Dpb11, Sld3 and Sld2 strongly enhances coherence and robustness of origin firing. The model rationalizes how experimentally observed inefficient replication from fewer origins is caused by premature activation of S-Cdk, while premature activity of the S-Cdk targets Sld2 and Sld3 results in DNA rereplication. Thus the model demonstrates how kinetic deregulation of the molecular network governing DNA replication may result in genomic instability