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排序方式: 共有186条查询结果,搜索用时 15 毫秒
1.
Unnikrishnan Nair N. Silpa Subhash S. M. Sunoj 《Biometrical journal. Biometrische Zeitschrift》2023,65(3):2200008
In the present communication, we propose a quantile-based measure for the divergence between two survival functions. This can also be used in a dynamic way where the divergence between survival functions varies with time. Several new properties of the proposed measure are investigated with suitable examples. The behavior of the measure for various reliability models is also investigated. A real data analysis is employed to compare the relative efficacy of two treatment groups using the proposed divergence measure. 相似文献
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Unnikrishnan Parayil Babu Velukutty Anu Gopinath 《Chemical Speciation and Bioavailability》2013,25(4):153-167
AbstractConcentrations of heavy metals (Cd, Co, Cr, Cu and Fe) in surface sediments and their partitioning behaviour between exchangeable, reducible (Fe-Mn oxide bound) and organic/residual phases of the sediments in a typical backwater system of Kerala, viz. the southern upstream part of Cochin Estuarine System (South India), have been studied. Spatial and temporal variations of trace metals are discussed with special reference to pH, dissolved oxygen, salinity, organic carbon and texture of sediment. Metal concentrations in the tide gated part of the estuary were found to be significantly higher when compared to metal concentrations reported from the unrestricted part of the Cochin estuarine system and also those from many of the unpolluted estuaries worldwide. The higher levels of heavy metals in the study area and their characteristic distribution and partitioning behaviour in the surficial sediments were attributed to the presence of a salinity barrier across the backwater system and also by the massive use of pesticides and chemical fertilizers in the vast area of agricultural land near the backwater system. 相似文献
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Issac Praveen Kumar Karan Rupmanjari Guru Ajay Pachaiappan R. Arasu Mariadhas Valan Al-Dhabi Naif Abdullah Choi Ki Choon Harikrishnan Ramasamy Raj Jesu Arockia 《Molecular biology reports》2021,48(8):5857-5872
Molecular Biology Reports - Plant-derived phytochemicals such as flavonoids have been explored to be powerful antioxidants that protect against oxidative stress-related diseases. In the present... 相似文献
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S. Indumathi R. Harikrishnan J. S. Rajkumar D. Sudarsanam M. Dhanasekaran 《Cell and tissue research》2013,352(3):537-549
The applicability of stem cells from the human endometrium and fallopian tube for regeneration is a fascinating area of research because of the role of these cells in dynamic tissue remodelling and their cyclical regenerative property during the menstrual cycle and pregnancy. Nevertheless, studies on the identity of biomarkers of these stem cells are limited and need to be extended. The present study has aimed at exploring the tissue-specific biomarkers of stem cells derived from the human endometrium and fallopian tube compared with those from bone marrow. Cells were isolated from human endometrium and fallopian tubes and characterized for biomarkers, including CD34, CD133, CD117, CD90, CD105, CD73, nestin, CD29, CD44, CD31, CD54, CD166, CD106, CD49d, CD45, ABCG2, SSEA4, OCT4, SOX2, CD140b and CD146, by flowcytometry. Both endometrium and fallopian tube sources exhibited positivity over a wide range of markers, as did bone marrow. In particular, they exhibited pluripotency, perivascular and mesenchymal stem cell markers and cell adhesion molecules, thereby suggesting their relevance in tissue repair and regeneration. Overall, the results of this study provide evidence for the presence of stem cells in the human endometrium and fallopian tube, which could thus represent additional stem cell sources for regenerative medicine. 相似文献
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The v-Abl protein encoded by Abelson murine leukemia virus (Ab-MLV) induces transformation of pre-B cells via a two-stage process. An initial proliferative phase during which cells with limited tumorigenic potential expand is followed by a crisis period marked by high levels of apoptosis and erratic growth. Transformants that survive this phase emerge as fully malignant cells and usually contain mutations that disable the p53 tumor suppressor pathway. Consistent with the importance of p53 in this process, pre-B cells from p53 null animals bypass crisis. Thus, the transformation process reflects a balance between signals from the v-Abl protein that drive transformation and those coming from the cellular response to inappropriate growth. One prediction of this hypothesis is that Ab-MLV mutants that are compromised in their ability to transform cells may be less equipped to overcome the effects of p53. To test this idea, we examined the ability of the P120/R273K mutant to transform pre-B cells from wild-type, p53 null, and Ink4a/Arf null mice. The SH2 domain of the v-Abl protein encoded by this mutant contains a substitution that affects the phosphotyrosine-binding pocket, and this mutant is compromised in its ability to transform NIH 3T3 and pre-B cells, especially at 39.5 degrees C. Our data reveal that loss of p53 or Ink4a/Arf locus products complements the transforming defect of the P120/R273K mutant, but it does not completely restore wild-type function. These results indicate that one important transforming function of v-Abl proteins is overcoming the effects of a functional p53 pathway. 相似文献
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Jesudason R Sato S Parameswaran H Araujo AD Majumdar A Allen PG Bartolák-Suki E Suki B 《Biophysical journal》2010,99(9):3076-3083
Many fundamental cellular and extracellular processes in the body are mediated by enzymes. At the single molecule level, enzyme activity is influenced by mechanical forces. However, the effects of mechanical forces on the kinetics of enzymatic reactions in complex tissues with intact extracellular matrix (ECM) have not been identified. Here we report that physiologically relevant macroscopic mechanical forces modify enzyme activity at the molecular level in the ECM of the lung parenchyma. Porcine pancreatic elastase (PPE), which binds to and digests elastin, was fluorescently conjugated (f-PPE) and fluorescent recovery after photobleach was used to evaluate the binding kinetics of f-PPE in the alveolar walls of normal mouse lungs. Fluorescent recovery after photobleach indicated that the dissociation rate constant (koff) for f-PPE was significantly larger in stretched than in relaxed alveolar walls with a linear relation between koff and macroscopic strain. Using a network model of the parenchyma, a linear relation was also found between koff and microscopic strain on elastin fibers. Further, the binding pattern of f-PPE suggested that binding sites on elastin unfold with strain. The increased overall reaction rate also resulted in stronger structural breakdown at the level of alveolar walls, as well as accelerated decay of stiffness and decreased failure stress of the ECM at the macroscopic scale. These results suggest an important role for the coupling between mechanical forces and enzyme activity in ECM breakdown and remodeling in development, and during diseases such as pulmonary emphysema or vascular aneurysm. Our findings may also have broader implications because in vivo, enzyme activity in nearly all cellular and extracellular processes takes place in the presence of mechanical forces. 相似文献
10.
Caloric restriction and genomic stability 总被引:1,自引:0,他引:1
Caloric restriction (CR) reduces the incidence and progression of spontaneous and induced tumors in laboratory rodents while increasing mean and maximum life spans. It has been suggested that CR extends longevity and reduces age-related pathologies by reducing the levels of DNA damage and mutations that accumulate with age. This hypothesis is attractive because the integrity of the genome is essential to a cell/organism and because it is supported by observations that both cancer and immunological defects, which increase significantly with age and are delayed by CR, are associated with changes in DNA damage and/or DNA repair. Over the last three decades, numerous laboratories have examined the effects of CR on the integrity of the genome and the ability of cells to repair DNA. The majority of studies performed indicate that the age-related increase in oxidative damage to DNA is significantly reduced by CR. Early studies suggest that CR reduces DNA damage by enhancing DNA repair. With the advent of genomic technology and our increased understanding of specific repair pathways, CR has been shown to have a significant effect on major DNA repair pathways, such as NER, BER and double-strand break repair. 相似文献