1,936 research outputs found
The Roles of Membrane Rafts in CD32A-Mediated Phagocytosis
Membrane rafts are highly dynamic heterogeneous sterol- and sphingolipid-rich micro-domains on cell surfaces. They are generally believed to provide residency for cell surface molecules (e.g., adhesion and signaling molecules) and scaffolding to facilitate the functions of these molecules such as membrane trafficking, receptor transport, cell signaling, and endocytosis.
The governing, or overall hypothesis, for this project is that membrane rafts provide residency for Fc[gamma]RIIA (CD32A) on K562 cells, and that by doing so they provide a platform from which Fc[gamma]RIIA initiate or carry out their functions, which include migration, signaling, phagocytic synapse formation, and internalization of IgG opsonized targets.
Using immuno-fluorescent laser scanning confocal microscopy and reflection interference microscopy (RIM), we studied the spatial and temporal distributions of membrane rafts and surface receptors, signaling molecules, and cell organelles during the formation of phagocytic contact areas. K562 cells, which naturally express CD32A, a cell surface receptor for the Fc portion of Immuno-globulin G(IgG), was chosen as a model for neutrophils. An opsonized target was modeled using a glass supported lipid bilayer reconstituted with IgG. CD32A was found to cluster and co-localize with membrane rafts. Placing the K562 cells on the lipid bilayer triggered a process of contact area formation that includes binding between receptors and ligands, their recruitment to the contact area, a concurrent membrane raft movement to and concentration in the contact area, and transport of CD32A, IgG, and membrane rafts to the Golgi complex. Characterization of these processes was performed using agents known to disrupt detergent resistant membranes (DRMs), dissolve actin microfilaments, and inhibit myosin motor activity, which abolished the CD32A clusters and prevented the contact area formation. 
The relevance to phagocytosis of contact area formation between K562 cells and lipid bilayers was demonstrated using micro-beads coated with a lipid bilayer reconstituted with IgG as the opsonized target instead of the glass supported planar lipid bilayer. Disruption of membrane rafts, salvation of the actin cytoskeleton, and inhibition of myosin II activity were found to inhibit phagocytosis.
These data suggest membrane rafts play several important roles in CD32A mediated phagocytosis including pre-clustering CD32A, transport of CD32A to the phagocytic cup, and transport of the opsonized target towards the Golgi complex. Here we have provided evidence that membrane rafts serve as platforms which are used to cluster CD32A and transport CD32A along the actin cytoskeleton to the site of phagocytic synapse formation thus allowing for the quick assembly of a phagocytic synapse.

Host genetics and tuberculosis susceptibility
Susceptibility to tuberculosis is multifactorial. The
importance of host genetic factors on the susceptibility
or resistance to tuberculosis has been emphasized by
many workers. Host genetic factors such as human
leucocyte antigens (HLA) and non-HLA genes that are
associated with the susceptibility to tuberculosis will
serve as genetic markers to predispose or predetermine
the development of the disease. Such markers may be
useful to understand the immune mechanism of susceptibility
or resistance to tuberculosis. Association of
various HLA and non-HLA genes with susceptibility
to tuberculosis in various ethnic population has been
established. HLA studies carried out in the Asian
region, especially in India, revealed the association of
HLA-DR2 and -DQ1 antigens with the susceptibility
to pulmonary TB. Further, studies on DNA typing
explored the association of DRB1 *1501 and *1502
(DR2 subtypes) in north Indian and DRB1 *1501, DRB1
*0601 (DQ1 subtype) and DPB1 *02 (DP2 subtype) in
south Indian population. Various studies on non-classical
major histocompatibility complex (MHC) genes and
non-MHC/non-HLA gene polymorphisms such as transporter
associated with antigen processing (TAP), tumour
necrosis factor a and b (TNF a and b), mannose binding
lectin (MBL), vitamin D receptor (VDR) (BsmI,
ApaI, TaqI and FokI polymorphisms), Interleukin-1
receptor antagonist (IL-1RA) and natural resistance
associated macrophage protein-1 (NRAMP-1) genes
revealed the association of TAP2 gene variant along
with HLA–DR2 and functional mutant homozygotes
(FMHs) of MBL with the susceptibility to pulmonary
TB. The polymorphic BsmI, ApaI, TaqI and FokI gene
variants of VDR showed differential susceptibility and
resistance with male and female subjects. These studies
suggest that multicandidate genes are associated with
the susceptibility to pulmonary tuberculosis in India
Role of Human Leucocyte Antigen (HLA) and Non-HLA genes in susceptibility or resistance to pulmonary tuberculosis
Human beings live in an environment endemic
to various diseases. Under such conditions, some
individuals are susceptible to certain diseases while
most are resistant to those diseases. This raises many
questions. One such question is whether the person
who is susceptible is genetically different from the
person who is resistant to the disease? Similarly, in
a family, one of the parents may be affected with a
particular disease (e.g. diabetes); among the children
born to the parents, if one child (younger one)
develops the disease and the other child (elder one)
does not, the question arises why did the younger
one develop the disease and the elder did not, when
both of them were living together with the affected
parent. This raises the possibility of the disease
being inherited from parents. If genetic factors play
a major role in disease susceptibility or resistance,
in what way are they associated with the disease
development? Do they control the immune response
to an antigen and/or pathogen? Do they play a role
in the immune mechanism of susceptibility or
resistance to disease? This article gives an account
of disease susceptibility or resistance in pulmonary
tuberculosis in the context of the host genetic factors,
i.e. HLA (Human Leucocyte Antigens) and non-
HLA genes and their gene products
Enhancing the Photovoltaic Performance of Dye-Sensitised Solar Cells for Building Integrated Applications
The building sector is responsible for more than one-third of global energy consumption. With increasing global population, the demand for energy efficiency buildings and on-site electricity production is rising. Building integrated photovoltaics (BIPV) is one of the most promising contributors to net-zero energy buildings, while also increasing the aesthetic value of the built environment. Among all the transparent solar cells, dye-sensitised solar cells (DSSCs) have low production cost, semi-transparency nature and a range of colours for building design. This thesis presents an overview of the current energy scenario and future prospects, state-of-the-art of photovoltaic technologies and the challenges in commercialising new generation solar cells. The first approach here is to find an efficient and low-cost alternative photoanode, sensitiser and counter electrode for DSSC. The tested materials are high surface area mesoporous TiO2, new ruthenium complex (m-HRD-1) sensitiser and Jet nebulizer spray coated CZTS. All the obtained results are compared with the commercial materials. Secondly, semi-transparent DSSCs are fabricated with different transparencies and their colour properties such as correlated colour temperature and colour rendering index are evaluated. Moreover, glazing properties and daylight glare analysis are studied to assess the possibility of adopting semi-transparent DSSCs into building architectures. Finally, a low solar concentrator is placed on the transparent-DSSCs to enhance their photovoltaic performance. The internal charge transfer mechanism of the DSSCs is also studied to understand the impact of the concentrated light. Furthermore, the performance of the concentrator coupled devices under different light intensities is studied. The results presented here provide a fertile base for further investigation, which will focus on improving the performance of all the new generation low cost solar cells using optical elements with new designs. The target is to improve the performance and stability of the transparent solar cell devices and use them as BIPV materials to overcome the challenges of the increasing energy demand
Algorithm for Pocket Milling using Zig-zag Tool Path
Pocket-milling operations are widely used for scooping out materials during the machiningof aircraft components. This paper presents a tool-path planning algorithm for pocket-millingusing zig-zag method. The algorithm consists of basically three modules, viz., generating toolpathelements using pocket geometry entities as input, finding out intersection points (edgepoints), and rearranging points in a zig-zag fashion. OPTPATH algorithm1,2 is used for generatingtool-path elements. These elements thus generated are used to find out the intersection pointswith all entities. The valid points are arranged in a zig-zag way, which are used for machiningany pocket considered. This algorithm works satisfactorily for all the pocket boundaries havingline-line, line-arc, and arc-arc geometry entities
Fuzzy-Logic based Effective Contour Representation of Occluded Objects
We present a fuzzy-based network for the sharpening of object contour even in the presence of occlusion. The contour representation of objects can be effectively handled by the structure tensor method. This work proposes an occlusion detection and filling strategy using the square patch selection method. Based on the interpolation method, the fuzzy-assisted square patch selection can be used to fill the occluded pixels. Due to the occluded pixels, the depth map may have anomalies in the low-texture and high-exposure areas. Before converting a depth map to a point cloud, it is essential to filter out the outliers in the depth map to obtain a more accurate point cloud. To improve the precision of the depth map, improved occlusion detection and management procedures is required.The occlusion regions may be confirmed through belief propagation, which may produce noisy results in occluded regions, sharp objects, and object boundaries. We strived to build a model that differentiates the occluded pixels from others by exploiting sharp boundary transitions. We have used a stereo geometry structure to develop the required deep neural models to handle occlusion. We built the model by creating layers for every pipeline component and made it to learn the contour representation model using an adaptive fuzzy-based approach. In existing approaches, the bias must be properly predicted with the Gaussian distribution. The proposed model eradicated the pixel bleeding effect by exploiting the bimodal distribution with Gaussian and SMD (Stereo Mixture Density) functions and by finding smoothening bias.The suitable depth values were assigned to the occluded regions obtained. The experimental results demonstrated that the proposed approach generates more stable depth maps with fewer constraints than the existing methods. The experimental results were compared with the standard SMD-Net and other state-of-the-art models
Training fisherwomen in fish processing
A project on training fisherwomen for their participation in rural development, sponsored by Ford Foundation (U.S.A), has been started by
the Centre for Agricultural and Rural Development Studies, T.N AU.,at the Fisheries College, Tuticorin. The project alms to select a few literate
rural women with leadership qualities for Imparting to them a training In the organisational and managerial aspects of a viable fish processing
enterprise. It also alms to assist the trained fisherwomen in organising and operating cottage industries by continued technical backing and thus
making the production units demonstration centres for the benefit of other women In the region.
The preliminary survey helped in identifying 5 candidates from each of the 3 selected villages. The pre-survey revealed the respondents'
choice of subject-areas to undergo training and their enthusiasm to learn techniques for the preparation of fish products like fish pickle and MasI
Meen. It also revealed their desire to be exposed to new products like fish wafers, fish oil, fish meal, shark fin-rays etc. The pre- and post evaluations
of the training programme helped In I) identifying training needs In the fields of marketing and financial management; II) Identifying
some low-cost technological substitutes for some of the commercial products (eg: 'Gadi' for vineger); ill) identifying the products or techniques
appreciated by the trainees and the products or techniques that received lukewarm response with reasons for such a response: Iv) Identifying the
level of managerial efficiency gained by the trainees and the kind of support required for each Individual to start cottage industries. The programme
Is being followed up by Interpersonal contacts and the co-ordinate efforts of the development departments
OPTIMIZATION OF SURFACE ROUGHNESS OF AISI 304 AUSTENITIC STAINLESS STEEL IN DRY TURNING OPERATION USING TAGUCHI DESIGN METHOD
The present work is concentrated with the dry turning of AISI 304 Austenitic Stainless Steel (ASS). This paper presents the influence of cutting parameters like cutting speed, feed rate and depth of cut on the surface roughness of austenitic stainless steel during dry turning. A plan of experiments based on Taguchi’s technique has been used to acquire the data. An orthogonal array, the signal to noise (S/N) ratio and the analysis of variance (ANOVA) are employed to investigate the cutting characteristics of AISI 304 austenitic stainless steel bars using TiC and TiCN coated tungsten carbide cutting tool. Finally the confirmation tests that have been carried out to compare the predicted values with the experimental values confirm its effectiveness in the analysis of surface roughness
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