25 research outputs found
Monitoring cholesterol organization in membranes at low concentrations utilizing the wavelength-selective fluorescence approach
We previously showed using a fluorescent analogue of cholesterol (NBD-cholesterol, or 25-[N-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-methyl]amino]-27-norcholesterol), that cholesterol may exhibit local organization at low concentrations in membranes by the formation of transbilayer tail-to-tail dimers of cholesterol (Rukmini, R., Rawat, S.S., Biswas, S.C., Chattopadhyay, A., 2001. Biophys. J. 81, 2122-2134). In this report, we have monitored the microenvironmental features of cholesterol monomers and dimers utilizing wavelength-selective fluorescence spectroscopy. Our results utilizing red edge excitation shift (REES) and wavelength-dependent change in fluorescence anisotropy show that the microenvironment around the NBD moieties in the dimer form is more rigid possibly due to steric constraints imposed by the dimer conformation. These results provide new information and are relevant in understanding the organization of cholesterol in membranes at low concentrations
TPMCF: Temporal QoS Prediction using Multi-Source Collaborative Features
Recently, with the rapid deployment of service APIs, personalized service
recommendations have played a paramount role in the growth of the e-commerce
industry. Quality-of-Service (QoS) parameters determining the service
performance, often used for recommendation, fluctuate over time. Thus, the QoS
prediction is essential to identify a suitable service among functionally
equivalent services over time. The contemporary temporal QoS prediction methods
hardly achieved the desired accuracy due to various limitations, such as the
inability to handle data sparsity and outliers and capture higher-order
temporal relationships among user-service interactions. Even though some recent
recurrent neural-network-based architectures can model temporal relationships
among QoS data, prediction accuracy degrades due to the absence of other
features (e.g., collaborative features) to comprehend the relationship among
the user-service interactions. This paper addresses the above challenges and
proposes a scalable strategy for Temporal QoS Prediction using Multi-source
Collaborative-Features (TPMCF), achieving high prediction accuracy and faster
responsiveness. TPMCF combines the collaborative-features of users/services by
exploiting user-service relationship with the spatio-temporal auto-extracted
features by employing graph convolution and transformer encoder with multi-head
self-attention. We validated our proposed method on WS-DREAM-2 datasets.
Extensive experiments showed TPMCF outperformed major state-of-the-art
approaches regarding prediction accuracy while ensuring high scalability and
reasonably faster responsiveness.Comment: 10 Pages, 7 figure
Membrane localization and dynamics of Nile Red: effect of cholesterol
The organization and dynamics of the hydrophobic fluorescent probe Nile Red incorporated in DOPC vesicles containing varying amounts of cholesterol has been monitored utilizing fluorescence-based approaches which include the red edge excitation shift (REES) approach and the parallax method for depth determination. Our results show that the fluorescence emission maximum, intensity, polarization, and lifetime of Nile Red vary with the cholesterol content of the membrane. Interestingly, Nile Red exhibits significant REES independent of the presence of cholesterol. This indicates that Nile Red is localized in a motionally restricted environment in the membrane. This is supported by analysis of membrane penetration depth of Nile Red using the parallax method which points out to a membrane interfacial localization of Nile Red. These results could be useful in analyzing membrane organization and heterogeneity in natural membranes using Nile Red
A Review on Cucumis sativus L. and its Anti-Ulcer Activity
The term "medicinal plant" refers to a plant that has active components with therapeutic properties and is used to treat disease or illness in various medical systems or conventionally. Every continent uses medicinal plants extensively and successfully. Herbal medicine is an extremely well-known and well-documented technique in Asia. Cucumis sativus L. is a well-known medicinal herb having variety of pharmacological activity. In traditional Unani medicine system this plant is use to cure variety of disease, ulcer is one of them. In this article we have discussed about its anti-ulcer potentiality
Organization and dynamics of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-labeled lipids: a fluorescence approach
Lipids that are labeled with the NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl) group are widely used as fluorescent analogues of native lipids in biological and model membranes to monitor a variety of processes. NBD-labeled lipids have previously been used to monitor the organization and dynamics of molecular assemblies such as membranes, micelles and reverse micelles utilizing the wavelength-selective fluorescence approach. In this paper, we have characterized the organization and dynamics of various NBD-labeled lipids using red edge excitation shift (REES) and other fluorescence approaches which include analysis of membrane penetration depths of the NBD group using the parallax method. We show here that the environment and location experienced by the NBD group of the NBD-labeled lipids could depend on the ionization state of the lipid. This could have potentially important implications in future studies involving NBD-labeled lipids as tracers in a cellular context