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W pracy rozpatrywano dwie strategie ewolucyjne (| + k) oraz (|, k) wy­korzystywane do rozwiązywania skomplikowanych problemów optymalizacji numerycz­nej. Omawiane w pracy strategie, inspirowane ewolucją biologiczną i genetyką, operują na populacjach o liczebności | i k potencjalnych rozwiązań z deterministyczną procedurą selekcji. Poprawność działania strategii jako poszukiwanie globalnego minimum funkcji kryterium przedstawiono na przykładzie minimalizacji funkcji Ackleya oraz estymacji pa­rametrów funkcji regresji II rodzaju.
The cancer stem cell theory elucidates not only the issue of tumour initiation and development, tumour’s ability to metastasise and reoccur, but also the ineffectiveness of conventional cancer therapy. This review examines stem cell properties, such as self-renewal, heterogeneity, and resistance to apoptosis. The ‘niche’ hypothesis is presented, and mechanisms of division, differentiation, self-renewal and signalling pathway regulation are explained. Epigenetic alterations and mutations of genes responsible for signal transmission may promote the formation of cancer stem cells. We also present the history of development of the cancer stem cell theory and discuss the experiments that led to the discovery and confirmation of the existence of cancer stem cells. Potential clinical applications are also considered, including therapeutic models aimed at selective elimination of cancer stem cells or induction of their proper differentiation.
Vegetable crops produced in the field from transplants for early harvest are ex-posed to various stressful conditions. Standard treatment for transplants before planting out is hardening, through lowering the temperature or less-frequent watering. This process launches several plant defensive mechanisms against stress. However, chilling must be adjusted to specific crop species or even cultivars, because their response to low tempera-ture may be different. The aim of the present experiment was to determine the effect of transplant chilling on the morphology of broccoli inflorescences. The experiment was conducted in the years 2011–2012. Broccoli transplants were chilled for 1 week or 2 weeks at 6, 10 and 14°C. Control plants were exposed to 18°C. Bud diameter and bud stalk length of broccoli inflorescences were measured, as well as diameter and weight of mature heads. In response to longer transplant chilling period, in the following growing stages plants formed inflorescences with longer bud stalks compared to the non-chilled control. The same tendency was observed for bud diameter in inflorescences. The greatest diameter of buds was noted for plants exposed to 10°C in comparison to the control, with buds about 29% smaller in diameter. Mean diameter of mature heads was the lowest for control plants, while the widest was obtained from plants chilled at 6°C or 10°C for 2 weeks, depending on the year. Chilling of transplants positively influenced the weight of broccoli heads at harvest in most cases, and the heaviest heads were obtained as a result of transplant chilling at 6°C. Relationships between temperature and some parameters of broccoli heads were found and regression equations were created.
The association between polymorphism in both DNA repair and xenobiotic metabolism genes and can­cer risk has been reported by many authors. Recent studies have revealed the genetic heterogeneity of various populations. Therefore, the aim of our study was to evaluate the frequency of selected polymor­phisms/mutations in 17 minor susceptibility genes and to analyze the pattern of their distribution in a group of 146 healthy, young Polish individuals.The results of our study show that the distribution of studied polymor­phisms displayed a distinct pattern.
CHEK2 gen encodes cell cycle checkpoint kinase 2 that participates in the DNA repair pathway, cell cycle regulation and apoptosis. Mutations in CHEK2 gene may result in kinase inactivation or reduce both catalytic activity and capability of binding other proteins. Some studies indicate that alterations in CHEK2 gene confers increase the risk of breast cancer and some other malignancies, while the results of other studies are inconclusive. Thus the significance of CHEK2 mutations in aetiology of breast cancer is still debatable. The aim of our study was to evaluate the relationship between the breast/ovarian cancer and CHEK2 variants by: i) the analysis of the frequency of selected CHEK2 variants in breast and ovarian cancer patients compared to the controls; ii) evaluation of relationships between the certain CHEK2 variants and clinico-histopathological and pedigree data. The study was performed on 284 breast cancer patients, 113 ovarian cancer patients and 287 healthy women. We revealed the presence of 430T > C, del5395 and IVS2 + 1G > A variants but not 1100delC in individuals from both study and control groups. We did not observe significant differences between cancer patients and controls neither in regard to the frequency nor to the type of CHEK2 variants. We discussed the potential application of CHEK2 variants in the evaluation of breast and ovarian cancer predisposition.
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