Culturing cells
ex vivo that differentiate and maintain
in vivo characteristics holds great promise not only for the pragmatic revelations of cell function but also in tissue engineering and ...regenerative medicine. Lack of
de-novo extra-cellular matrix (ECM) milieu, which plays a crucial role in generating physical and chemical signals besides providing structural support is attributed to be the major hurdle in normal cell growth
in vitro. Hence, to comprehend the outcome of cell biology research in clinical context, it is important that the cell culture based models should incorporate both the three dimensional (3D) organization and multi cellular complexity of an organ while allowing experimental interventions in a desirable manner. This calls for the development of ECM-mimicking 3D scaffold, which can be integrated with relevant ECM cues to offer cell interactive versatility for different medical and non-medical applications. Present review discusses the status of ECM mimicking for 3D cell culture and its diverse implications.
DNA damage induced by reactive oxygen species and several chemotherapeutic agents promotes both p53 and poly (ADP-ribose) polymerase (PARP) activation. p53 activation is well known to regulate ...apoptotic cell death, whereas robust activation of PARP-1 has been shown to promote a necrotic cell death associated with energetic collapse. Here we identify a novel role for p53 in modulating PARP enzymatic activity to regulate necrotic cell death. In mouse embryonic fibroblasts, human colorectal and human breast cancer cell lines, loss of p53 function promotes resistance to necrotic, PARP-mediated cell death. We therefore demonstrate that p53 can regulate both necrotic and apoptotic cell death, mutations or deletions in this tumor-suppressor protein may be selected by cancer cells to provide not only their resistance to apoptosis but also to necrosis, and explain resistance to chemotherapy and radiation even when it kills via non-apoptotic mechanisms.
A previous contribution in the literature dealt with an interesting way of compensating for the source resistance in the familiar bandpass and bandstop forms of the Wien network in the sense that the ...centre frequency is maintained at the value for an ideal source. In the present article, the author makes a detailed analysis of these circuits, and shows that in both configurations, not only the centre frequency is maintained constant, but the frequency response can also be improved thereby.
The simplest network for matching a load resistance <inline-formula> <tex-math notation="TeX">R_{L}</tex-math></inline-formula> to a source resistance <inline-formula> <tex-math notation="TeX">R_{s} ...</tex-math></inline-formula> at a single frequency is analyzed to find an expression for the matching bandwidth with a specified tolerance on the reflection coefficient. The results are used to find the characteristics of dual- and triple-frequency impedance matching networks, designed by applying frequency transformation to the single-frequency network. Finally, comments are made about some general features of multiple-frequency matching networks.
The first Hall network is examined in detail to find and optimize the peak magnitude, which occurs in its bandpass response. It is shown that the same network with a reorientation, can act as a ...bandstop filter. This is also examined in detail and choice of parameters to maximise the peak/minimize the dip is discussed. In both networks, the critical frequency (of peak/dip) can be controlled by a potentiometer, keeping the magnitude of the peak/dip a constant.
Engineering a functional tissue ex vivo requires a synchronized effort towards developing technologies for ECM mimicking scaffold and cultivating tissue-specific cells in an integrated and controlled ...manner. Cell-interactive scaffolds in three dimensions (3D), designed and processed appropriately with an apt biomaterial to yield optimal porosity and mechanical strength is the key in tissue engineering (TE). In order to accomplish these facets in a 3D scaffold, multiple techniques and processes have been explored by researchers all over the world. New techniques offering reasonable flexibility to use blends of different materials for integrated tissue-specific mechanical strength and biocompatibility have an edge over conventional methods. They may allow a combinatorial approach with a mix of materials while incorporating multiple processing techniques for successful creation of tissue-specific ECM mimics. In this review, we analyze the material requirement from different TE perspectives, while discussing pros and cons of advanced fabrication techniques for scale-up manufacturing.
In this brief, we present the redesign the familiar bridged-T and parallel-T RC networks, for single resistance control of the notch/null frequencies, The two networks are analyzed, and the relevant ...parameters and conditions are derived. The transfer functions are simulated for various values of parameters, and the conclusions are recorded.
Wetting transition of water on graphite and boron-nitride (BN) surfaces is investigated by molecular dynamics simulation. In particular, we report the effect of temperature and system size on the ...contact angle of water droplet on the two surfaces. Wetting temperature of water on graphite is found to be 470
±
5
K, which is in good agreement with the estimate of Zhao (Phys. Rev. B 76 (2007) 041402) using grand-canonical Monte Carlo simulations. On the other hand, wetting temperature of water on BN surface is estimated to be lower, 438
±
5
K. Temperature dependence of line tension of water droplet on both the surfaces is also studied, and found to vary between 10
−10 and 10
−9
N for temperature in the range of 300–420
K. In this work, line tension for water on graphite and BN surfaces is observed to have a logarithmic proportional behavior with the contact angle.
Symmetry permeates nature and is fundamental to all laws of physics. One example is parity (mirror) symmetry, which implies that flipping left and right does not change the laws of physics. Laws for ...electromagnetism, gravity and the subatomic strong force respect parity symmetry, but the subatomic weak force does not. Historically, parity violation in electron scattering has been important in establishing (and now testing) the standard model of particle physics. One particular set of quantities accessible through measurements of parity-violating electron scattering are the effective weak couplings C2q, sensitive to the quarks' chirality preference when participating in the weak force, which have been measured directly only once in the past 40 years. Here we report a measurement of the parity-violating asymmetry in electron-quark scattering, which yields a determination of 2C2u - C2d (where u and d denote up and down quarks, respectively) with a precision increased by a factor of five relative to the earlier result. These results provide evidence with greater than 95 per cent confidence that the C2q couplings are non-zero, as predicted by the electroweak theory. They lead to constraints on new parity-violating interactions beyond the standard model, particularly those due to quark chirality. Whereas contemporary particle physics research is focused on high-energy colliders such as the Large Hadron Collider, our results provide specific chirality information on electroweak theory that is difficult to obtain at high energies. Our measurement is relatively free of ambiguity in its interpretation, and opens the door to even more precise measurements in the future.
Community-based programs in rural low-and middle-income country settings are well-placed to conduct gender transformative activities that aid program sustainability and catalyse wider social change, ...such as reducing gender inequities that in turn improve health outcomes. The Anchal program is a drowning prevention intervention for children aged 1-5 years old in rural Bangladesh. It provides community crèche-based supervision delivered by local trained paid-female volunteers. We aimed to identify the influence of the Anchal program on gender norms and behaviours in the community context, and the effects these had on program delivery and men and women's outcomes. Qualitative in-depth interviews, focus group discussions and observations were conducted with program beneficiaries and providers. Gender outcomes were analysed using FHI 360's Gender Integration Framework. The Anchal program was found to be a gender accommodating program as it catered for communities' gender-based roles and constraints but did not actively seek to change underlying beliefs, perceptions and norms that led to these. The program in some cases enhanced the independence and status of female community staff. This changed perceptions of communities towards acceptable levels of physical mobility and community involvement for women. Conversely, gender affected program delivery by reducing the ability of female supervisory staff to engage with male community leaders. The double burden of wage and household labour carried by local female staff also limited performance and progression. Gender-based constraints on staff performance, attrition and community engagement affected efficiency of program delivery and sustainability. The Anchal program both adapted to and shaped community gender norms and roles. The program has well-established relationships in the community and can be leveraged to implement gender transformative activities to improve gender-based equity. Health programs can broaden their impacts and target social determinants of health like gender equity to increase program sustainability and promote equitable health outcomes.
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