144 research outputs found
Уровень обслуживания как показатель надёжности улично-дорожной сети
ABSTRACT The article assesses understanding and interpretation of scientific categories «reliability», «refusal», «congestion». The possibility of using the service level indicator as a criterion of reliability of functioning of street- road network is substantiated, bearing in mind that it reflects in a complex the data on economy, convenience and traffic safety, and through this, the state of a transport flow. Different approaches are given to determine the level of service, to classify features and signs of the work performed. Further directions for improving reliability of highways, searching for the most variable indicator of reliability of the urban transport network are formulated. Keywords: street-road network, reliability, congestion, flow, failure, service level, time buffer, buffer index.Полный текст на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).В статье оцениваются понимание и трактовка научных категорий «надёжность», «отказ», «конгестия». Обосновывается возможность использования показателя уровня обслуживания как критерия надёжности функционирования улично-дорожной сети, имея в виду, что он отражает в комплексе данные об экономичности, удобстве и безопасности движения, а посредством этого и состояние транспортного потока. Приводятся разные подходы к определению уровня обслуживания, к классификации особенностей и признаков выполняемой работы. Формулируются дальнейшие направления совершенствования надёжности автомобильных дорог, поиска наиболее вариативного показателя безотказности городской транспортной сети
Modeling of the Magnetic Susceptibilities of the Ambient- and High-Pressure Phases of (VO)_{2}P_{2}O_{7}
The magnetic susceptibilities chi versus temperature T of powders and single
crystals of the ambient-pressure (AP) and high-pressure (HP) phases of
(VO)_{2}P_{2}O_{7} are analyzed using an accurate theoretical prediction of
chi(T, J1, J2) for the spin-1/2 antiferromagnetic alternating-exchange (J1, J2)
Heisenberg chain. The results are consistent with recent models with two
distinct types of alternating-exchange chains in the AP phase and a single type
in the HP phase. The spin gap for each type of chain is derived from the
respective set of two fitted alternating exchange constants and the one-magnon
dispersion relation for each of the two types of chains in the AP phase is
predicted. The influences of interchain coupling on the derived intrachain
exchange constants, spin gaps, and dispersion relations are estimated using a
mean-field approximation for the interchain coupling. The accuracies of the
spin gaps obtained using fits to the low-T chi(T) data by theoretical low-T
approximations are determined. The results of these studies are compared with
previously reported estimates of the exchange couplings and spin gaps in the AP
and HP phases and with the magnon dispersion relations in the AP phase measured
previously using inelastic neutron scattering.Comment: 25 two-column REVTeX pages, 16 embedded figures, 6 tables. Figures 9
and 10 and Sec. IIIC revised due to errors in Eq. (1) of Ref. 24 which gives
the theoretical one-magnon dispersion relation for coupled
alternating-exchange chains. Minor revisions also made in other section
Glutamine Acts as a Neuroprotectant against DNA Damage, Beta-Amyloid and H2O2-Induced Stress
Glutamine is the most abundant free amino acid in the human blood stream and is ‘conditionally essential’ to cells. Its intracellular levels are regulated both by the uptake of extracellular glutamine via specific transport systems and by its intracellular synthesis by glutamine synthetase (GS). Adding to the regulatory complexity, when extracellular glutamine is reduced GS protein levels rise. Unfortunately, this excess GS can be maladaptive. GS overexpression is neurotoxic especially if the cells are in a low-glutamine medium. Similarly, in low glutamine, the levels of multiple stress response proteins are reduced rendering cells hypersensitive to H2O2, zinc salts and DNA damage. These altered responses may have particular relevance to neurodegenerative diseases of aging. GS activity and glutamine levels are lower in the Alzheimer's disease (AD) brain, and a fraction of AD hippocampal neurons have dramatically increased GS levels compared with control subjects. We validated the importance of these observations by showing that raising glutamine levels in the medium protects cultured neuronal cells against the amyloid peptide, Aβ. Further, a 10-day course of dietary glutamine supplementation reduced inflammation-induced neuronal cell cycle activation, tau phosphorylation and ATM-activation in two different mouse models of familial AD while raising the levels of two synaptic proteins, VAMP2 and synaptophysin. Together, our observations suggest that healthy neuronal cells require both intracellular and extracellular glutamine, and that the neuroprotective effects of glutamine supplementation may prove beneficial in the treatment of AD
Change of Gene Structure and Function by Non-Homologous End-Joining, Homologous Recombination, and Transposition of DNA
An important objective in genome research is to relate genome structure to gene function. Sequence comparisons among orthologous and paralogous genes and their allelic variants can reveal sequences of functional significance. Here, we describe a 379-kb region on chromosome 1 of maize that enables us to reconstruct chromosome breakage, transposition, non-homologous end-joining, and homologous recombination events. Such a high-density composition of various mechanisms in a small chromosomal interval exemplifies the evolution of gene regulation and allelic diversity in general. It also illustrates the evolutionary pace of changes in plants, where many of the above mechanisms are of somatic origin. In contrast to animals, somatic alterations can easily be transmitted through meiosis because the germline in plants is contiguous to somatic tissue, permitting the recovery of such chromosomal rearrangements. The analyzed region contains the P1-wr allele, a variant of the genetically well-defined p1 gene, which encodes a Myb-like transcriptional activator in maize. The P1-wr allele consists of eleven nearly perfect P1-wr 12-kb repeats that are arranged in a tandem head-to-tail array. Although a technical challenge to sequence such a structure by shotgun sequencing, we overcame this problem by subcloning each repeat and ordering them based on nucleotide variations. These polymorphisms were also critical for recombination and expression analysis in presence and absence of the trans-acting epigenetic factor Ufo1. Interestingly, chimeras of the p1 and p2 genes, p2/p1 and p1/p2, are framing the P1-wr cluster. Reconstruction of sequence amplification steps at the p locus showed the evolution from a single Myb-homolog to the multi-gene P1-wr cluster. It also demonstrates how non-homologous end-joining can create novel gene fusions. Comparisons to orthologous regions in sorghum and rice also indicate a greater instability of the maize genome, probably due to diploidization following allotetraploidization
Genetic approaches for studying transgene inheritance and genetic recombination in three successive generations of transformed tobacco
Repair-Mediated Duplication by Capture of Proximal Chromosomal DNA Has Shaped Vertebrate Genome Evolution
DNA double-strand breaks (DSBs) are a common form of cellular damage that can lead to cell death if not repaired promptly. Experimental systems have shown that DSB repair in eukaryotic cells is often imperfect and may result in the insertion of extra chromosomal DNA or the duplication of existing DNA at the breakpoint. These events are thought to be a source of genomic instability and human diseases, but it is unclear whether they have contributed significantly to genome evolution. Here we developed an innovative computational pipeline that takes advantage of the repetitive structure of genomes to detect repair-mediated duplication events (RDs) that occurred in the germline and created insertions of at least 50 bp of genomic DNA. Using this pipeline we identified over 1,000 probable RDs in the human genome. Of these, 824 were intra-chromosomal, closely linked duplications of up to 619 bp bearing the hallmarks of the synthesis-dependent strand-annealing repair pathway. This mechanism has duplicated hundreds of sequences predicted to be functional in the human genome, including exons, UTRs, intron splice sites and transcription factor binding sites. Dating of the duplication events using comparative genomics and experimental validation revealed that the mechanism has operated continuously but with decreasing intensity throughout primate evolution. The mechanism has produced species-specific duplications in all primate species surveyed and is contributing to genomic variation among humans. Finally, we show that RDs have also occurred, albeit at a lower frequency, in non-primate mammals and other vertebrates, indicating that this mechanism has been an important force shaping vertebrate genome evolution
Universal DNA methylation age across mammalian tissues
Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.Publisher PDFPeer reviewe
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Universal DNA methylation age across mammalian tissues.
Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals
РЕЗУЛЬТАТЫ СРАВНЕНИЯ ТЕРАПЕВТИЧЕСКОЙ ЭКВИВАЛЕНТНОСТИ ПРЕПАРАТА ОКСАЛИПЛАТИН-РОНЦ® (ПРОИЗВОДСТВА ФИЛИАЛА «НАУКОПРОФИ» ФГБУ «РОНЦ ИМЕНИ Н.Н. БЛОХИНА» МИНЗДРАВА РОССИИ) С ПРЕПАРАТОМ ЭЛОКСАТИН® (АВЕНТИС ФАРМА, ВЕЛИКОБРИТАНИЯ) В СОСТАВЕ СХЕМЫ MFOLFOX6 В КАЧЕСТВЕ ПЕРВОЙ ЛИНИИ ХИМИОТЕРАПИИ У ПАЦИЕНТОВ С МЕТАСТАТИЧЕСКИМ РАКОМ ТОЛСТОЙ КИШКИ
The combination of fluoropyrimidines with oxaliplatin is one of the standard first line chemotherapy of metastatic colorectal cancer (mCRC). In Russian cancer research center was performed a full cycle of production the drug Oxaliplatin-RONC®, showed equivalence to Eloxatin® in vitro and in vivo. The main purpose of this study was to evaluate the therapeutic equivalence of Oxaliplatin-RONC ® and Eloxatin® in mFOLFOX6 combination as a first line of chemotherapy in patients with mCRR. The second purpose was to compare the safety of drugs.A total of 59 patients were enrolled in the study. Patients were assigned in a 1:1 ratio to receive up to 9 cycles of mFOLFOX6 with Oxaliplatin-RONC® or Eloxatin®; cycles were repeated every 14 days. 30 patients were randomly assigned to OxaliplatinRCRC® and 29 to Eloxatin®. The objective response rate was 46,67% in the OxaliplatinRONC® group and 37,93% in the Eloxatin® group (р (non inferiority)=0,046); 97,5% CI,–0,16–0,33). The median progression-free survival was 6,9 months in the OxaliplatinRONC® group, as compared with 7 months in the Eloxatin® group (P=0.571). The median of duration response rate was 5,5 months in the Oxaliplatin-RONC® and 6,2 months in the Eloxatin® group (p=0.8). The incidence of adverse events grade 3 or 4 was comparable in groups. Oxaliplatin-RONC® and Eloxatin® in the mFOLFOX6 combination showed comparable efficacy and safety in patients with mCRC. Цель исследования. Комбинация фторпиримидинов и оксалиплатина является одним из вариантов первой линии химиотерапии больных метастатическим раком толстой кишки. В филиале «Наукопрофи» ФГБУ «РОНЦ имени Н. Н. Блохина» Минздрава России осуществляется полный цикл производства готовой лекарственной формы препарата Оксалиплатин-РОНЦ® из выпущенной в Германии фармацевтической субстанции. Оксалиплатин-РОНЦ® в доклинических исследованиях invitro и invivo показал эквивалентность оригинальному препарату Элоксатин®. Основной целью данного исследования была оценка терапевтической эквивалентности препарата Оксалиплатин-РОНЦ® и препарата Элоксатин® в составе схемы mFOLFOX6 в качестве 1 линии химиотерапии у больных метастатическим раком толстой кишки. Дополнительной целью данного исследования явилось сравнение безопасности двух препаратов.Материалы и методы. В исследование были включены 59 пациентов с метастатическим раком толстой кишки. Пациенты рандомизированы в соотношении 1:1 и распределены в одну из двух групп терапии: 30 пациентов получали препарат Оксалиплатин-РОНЦ®, 29 – препарат Элоксатин® в составе схемы химиотерапии mFOLFOX6 каждые 2 недели, всего 9 курсов. Основным критерием эффективности явилась частота достижения объективного ответа.Результаты. Объективный ответ на терапию в группе пациентов, получавших Оксалиплатин-РОНЦ®, составил 46,6%, в группе с Элоксатином® – 37,9% (97,5%ДИ, 0,16–0,33, р (non inferiority)=0,046). Медиана времени до прогрессирования в группе Оксалиплатин-РОНЦ® составила 6,9 мес, а в группе Элоксатин® – 7 мес (p=0,5). Медиана длительности объективного ответа у пациентов с подтвержденным объективным ответом в группе Оксалиплатин-РОНЦ® составила 5,5 мес, а в группе Элоксатин® – 6,2 мес (p=0,8). Не было выявлено статистически значимых различий между препаратами по частоте осложнений 3–4 степени.Вывод. В исследовании показана сопоставимая эффективность и переносимость препарата Оксалиплатин-РОНЦ® в сравнении с препаратом Элоксатин® в составе схемы химиотерапии mFOLFOX6 у больных метастатическим раком толстой кишки в качестве первой линии лечения
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