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401.
402.
N. Manzoor O. Anwar Bég S. Shaheen 《Computer methods in biomechanics and biomedical engineering》2019,22(7):685-695
Bionic systems frequently feature electromagnetic pumping and offer significant advantages over conventional designs via intelligent bio-inspired properties. Complex wall features observed in nature also provide efficient mechanisms which can be utilized in biomimetic designs. The characteristics of biological fluids are frequently non-Newtonian in nature. In many natural systems super-hydrophobic slip is witnessed. Motivated by these phenomena, in this paper, we discussed a mathematical model for the cilia-generated propulsion of an electrically-conducting viscoelastic physiological fluid in a ciliated channel under the action of magnetic field. The rheological behavior of the fluid is simulated with the Johnson-Segalman constitutive model which allows internal wall slip. The regular or coordinated movement of the ciliated edges (which line the internal walls of the channel) is represented by a metachronal wave motion in the horizontal direction which generates a two-dimensional velocity profile. This mechanism is imposed by a periodic boundary condition which generates propulsion in the channel flow. Under the classical lubrication approximation, the boundary value problem is non-dimensionalized and solved analytically with a perturbation technique. The influence of the geometric, rheological (slip and Weissenberg number) and magnetic parameters on velocity, pressure gradient and the pressure rise (evaluated via the stream function in symbolic software) are presented graphically and interpreted at length. 相似文献
403.
Hilfiker-Kleiner D Kaminski K Podewski E Bonda T Schaefer A Sliwa K Forster O Quint A Landmesser U Doerries C Luchtefeld M Poli V Schneider MD Balligand JL Desjardins F Ansari A Struman I Nguyen NQ Zschemisch NH Klein G Heusch G Schulz R Hilfiker A Drexler H 《Cell》2007,128(3):589-600
Postpartum cardiomyopathy (PPCM) is a disease of unknown etiology and exposes women to high risk of mortality after delivery. Here, we show that female mice with a cardiomyocyte-specific deletion of stat3 develop PPCM. In these mice, cardiac cathepsin D (CD) expression and activity is enhanced and associated with the generation of a cleaved antiangiogenic and proapoptotic 16 kDa form of the nursing hormone prolactin. Treatment with bromocriptine, an inhibitor of prolactin secretion, prevents the development of PPCM, whereas forced myocardial generation of 16 kDa prolactin impairs the cardiac capillary network and function, thereby recapitulating the cardiac phenotype of PPCM. Myocardial STAT3 protein levels are reduced and serum levels of activated CD and 16 kDa prolactin are elevated in PPCM patients. Thus, a biologically active derivative of the pregnancy hormone prolactin mediates PPCM, implying that inhibition of prolactin release may represent a novel therapeutic strategy for PPCM. 相似文献
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Saeed Ahmad Asad Said Muhammad Muhammad Farooq Aftab Afzal Martin Broadley Scott Young Helen West 《Acta Physiologiae Plantarum》2015,37(1):1-9
Stomatal behavior in response to drought has been the focus of intensive research, but less attention has been paid to stomatal density. In this study, 5-week-old maize seedlings were exposed to different soil water contents. Stomatal density and size as well as leaf gas exchange were investigated after 2-, 4- and 6-week of treatment, which corresponded to the jointing, trumpeting, and filling stages of maize development. Results showed that new stomata were generated continually during leaf growth. Reduced soil water content significantly stimulated stomatal generation, resulting in a significant increase in stomatal density but a decrease in stomatal size and aperture. Independent of soil water conditions, stomatal density and length in the trumpeting and filling stages were greater than in the jointing stage. Irrespective of growth stage, severe water deficit significantly reduced stomatal conductance (G s), decreasing the leaf transpiration rate (T r) and net photosynthetic rate (P n). Stomatal density was significantly negatively correlated with both P n and T r but more strongly with T r, so the leaf instantaneous water use efficiency (WUE i ) correlated positively with stomatal density. In conclusion, drought led to a significant increase in stomatal density and a reduction in stomatal size and aperture, resulting in decreased P n and T r. Because the negative correlation of stomatal density to T r was stronger than that to P n, leaf WUE i tended to increase. 相似文献
407.
Ali Muhammad Mehmood Azra Anjum Muhammad Sohail Tarrar Moazzam Nazir Khan Shaheen N. Riazuddin Sheikh 《Molecular and cellular biochemistry》2015,403(1-2):267-276
Molecular and Cellular Biochemistry - Type 1 diabetes mellitus (DM) is a strong risk factor for the development of diabetic cardiomyopathy (DCM) which is the leading cause of morbidity and... 相似文献
408.
Yang GX Lian ZX Kikuchi K Moritoki Y Ansari AA Liu YJ Ikehara S Gershwin ME 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(11):7281-7287
Plasmacytoid dendritic cells (pDCs) play a central role in host innate and adaptive immunity and are thought to be of lymphoid origin. However, in IL-7Ralpha-/- mice, which are deficient in T and B lymphocytes, pDCs are still found in lymphoid organs, which suggests that there is a lymphoid-independent pathway for the development of pDCs. Previous work has demonstrated that pDCs originate from both lymphoid and myeloid progenitors (MPs). However, it is not clear whether the function of pDCs is different relative to their origin. In an effort to compare the characteristics and functions between pDCs generated from different progenitors, we performed adoptive transfer studies using highly enriched populations of common lymphoid progenitors (CLPs) and MPs from the bone marrow of control mice and examined their potential and developmental kinetics for the generation of pDCs. Interestingly, although CLPs were polarized to generate pDCs, MPs were polarized to generate conventional dendritic cells and the kinetics of pDC generation from MPs was reached earlier than from CLPs. Furthermore, CLPs have the potential to generate more pDCs on a per cell basis. Moreover, MP-derived pDCs produce relatively higher levels of IFN-alpha than CLP-derived pDCs following CpG stimulation. These data indicate that MPs are multipotential and have the capacity to develop into not only myeloid cells, but also pDCs, which have distinct characteristics and function compared to that of lymphoid origin and, therefore, imply a more important role for MP-derived pDCs in conditions where the function of lymphoid progenitors is impaired or compromised. 相似文献
409.
Cynthia Shaheen Cameron Hastie Kimberly Metera Shane Scott Zhi Zhang Sitong Chen Gracia Gu Lisa Weber Brian Munsky Fedor Kouzine David Levens Craig Benham Sabrina Leslie 《Nucleic acids research》2022,50(5):2754
Many cellular processes occur out of equilibrium. This includes site-specific unwinding in supercoiled DNA, which may play an important role in gene regulation. Here, we use the Convex Lens-induced Confinement (CLiC) single-molecule microscopy platform to study these processes with high-throughput and without artificial constraints on molecular structures or interactions. We use two model DNA plasmid systems, pFLIP-FUSE and pUC19, to study the dynamics of supercoiling-induced secondary structural transitions after perturbations away from equilibrium. We find that structural transitions can be slow, leading to long-lived structural states whose kinetics depend on the duration and direction of perturbation. Our findings highlight the importance of out-of-equilibrium studies when characterizing the complex structural dynamics of DNA and understanding the mechanisms of gene regulation. 相似文献
410.
Harold M. McClure Daniel C. Anderson Patricia N. Fultz Aftab A. Ansari Tamar Jehuda-Cohen Francois Villinger Sherry A. Klumpp William Switzer Ellen Lockwood Anne Brodie Harry Keyserling 《Journal of medical primatology》1991,20(4):182-187
Fifteen SIV-infected rhesus monkeys delivered 13 livebirths and two stillbirths; one livebirth died at three days of age. While all infants were culture-negative for SIV at birth, nine had maternal antibodies that disappeared by six months of age. Three infants subsequently seroconverted and became virus positive at 9–15 months. Milk samples from all mothers were virus-negative at parturition but samples from four animals were virus-positive at nine and 12 months. This study documents maternal transmission of SIV and suggests transmission by breast-feeding. 相似文献