Non-Invasive Glucose Monitoring Using Optical Sensor and Machine Learning Techniques for Diabetes Applications.

Diabetes is a major public health challenge affecting more than 451 million people. Physiological and experimental factors influence the accuracy of non-invasive glucose monitoring, and these need to be overcome before replacing the finger prick method. Also, the suitable employment of machine learning techniques can significantly improve the accuracy of glucose predictions.

Association Between Obesity and Cardiovascular Outcomes: Updated Evidence from Meta-analysis Studies.

Purpose Of Review: The prevalence of obesity and cardiovascular disease (CVD) has been increasing worldwide. Studies examining the association between adiposity and CVD outcomes have produced conflicting findings. The interplay between obesity and CVD outcomes in the general population and in specific subpopulations is complex and requires further elucidation.

Early detection of metabolic dysregulation using water T analysis of biobanked samples.

Background: The ability to use frozen biobanked samples from cohort studies and clinical trials is critically important for biomarker discovery and validation. Here we investigated whether plasma and serum water transverse relaxation times (T) from frozen biobanked samples could be used as biomarkers for metabolic syndrome (MetS) and its underlying conditions, specifically insulin resistance, dyslipidemia, and subclinical inflammation.

Methods: Plasma and serum aliquots from 44 asymptomatic, non-diabetic human subjects were biobanked at -80°C for 7-9 months.

Aptamer-based search for correlates of plasma and serum water T: implications for early metabolic dysregulation and metabolic syndrome.

Background: Metabolic syndrome is a cluster of abnormalities that increases the risk for type 2 diabetes and atherosclerosis. Plasma and serum water T from benchtop nuclear magnetic resonance relaxometry are early, global and practical biomarkers for metabolic syndrome and its underlying abnormalities. In a prior study, water T was analyzed against ~ 130 strategically selected proteins and metabolites to identify associations with insulin resistance, inflammation and dyslipidemia.

Water T as an early, global and practical biomarker for metabolic syndrome: an observational cross-sectional study.

Background: Metabolic syndrome (MetS) is a highly prevalent condition that identifies individuals at risk for type 2 diabetes mellitus and atherosclerotic cardiovascular disease. Prevention of these diseases relies on early detection and intervention in order to preserve pancreatic β-cells and arterial wall integrity. Yet, the clinical criteria for MetS are insensitive to the early-stage insulin resistance, inflammation, cholesterol and clotting factor abnormalities that characterize the progression toward type 2 diabetes and atherosclerosis.

Compact NMR relaxometry of human blood and blood components.

Nuclear magnetic resonance relaxometry is a uniquely practical and versatile implementation of NMR technology. Because it does not depend on chemical shift resolution, it can be performed using low-field compact instruments deployed in atypical settings. Early relaxometry studies of human blood were focused on developing a diagnostic test for cancer.

Structural determinants of ligand binding in the ternary complex of human ileal bile acid binding protein with glycocholate and glycochenodeoxycholate obtained from solution NMR.

Unlabelled: Besides aiding digestion, bile salts are important signal molecules exhibiting a regulatory role in metabolic processes. Human ileal bile acid binding protein (I-BABP) is an intracellular carrier of bile salts in the epithelial cells of the distal small intestine and has a key role in the enterohepatic circulation of bile salts. Positive binding cooperativity combined with site selectivity of glycocholate and glycochenodeoxycholate, the two most abundant bile salts in the human body, make human I-BABP a unique member of the family of intracellular lipid binding proteins.

Nanofluidity of fatty acid hydrocarbon chains as monitored by benchtop time-domain nuclear magnetic resonance.

The functional properties of lipid-rich assemblies such as serum lipoproteins, cell membranes, and intracellular lipid droplets are modulated by the fluidity of the hydrocarbon chain environment. Existing methods for monitoring hydrocarbon chain fluidity include fluorescence, electron spin resonance, and nuclear magnetic resonance (NMR) spectroscopy; each possesses advantages and limitations. Here we introduce a new approach based on benchtop time-domain (1)H NMR relaxometry (TD-NMR).

NMR structure of a fungal virulence factor reveals structural homology with mammalian saposin B.

The fungal protein CBP (calcium binding protein) is a known virulence factor with an unknown virulence mechanism. The protein was identified based on its ability to bind calcium and its prevalence as Histoplasma capsulatum's most abundant secreted protein. However, CBP has no sequence homology with other CBPs and contains no known calcium binding motifs.

Structural features responsible for the biological stability of Histoplasma's virulence factor CBP.

The virulence factor CBP is the most abundant protein secreted by Histoplasma capsulatum, a pathogenic fungus that causes histoplasmosis. Although the biochemical function and pathogenic mechanism of CBP are unknown, quantitative Ca (2+) binding measurements indicate that CBP has a strong affinity for calcium ( K D = 6.45 +/- 0.

The RXRalpha C-terminus T462 is a NMR sensor for coactivator peptide binding.

The C-terminal activation function-2 (AF-2) helix plays a crucial role in retinoid X receptor alpha (RXRalpha)-mediated gene expression. Here, we report a nuclear magnetic resonance (NMR) study of the RXRalpha ligand-binding domain complexed with 9-cis-retinoic acid and a glucocorticoid receptor-interacting protein 1 peptide. The AF-2 helix and most of the C-terminal residues were undetectable due to a severe line-broadening effect.

Kinetic mechanism of ligand binding in human ileal bile acid binding protein as determined by stopped-flow fluorescence analysis.

Cooperative ligand binding to human ileal bile acid binding protein (I-BABP) was studied using the stopped-flow fluorescence technique. The kinetic data obtained for wild-type protein are in agreement with a four-step mechanism where after a fast conformational change on the millisecond time scale, the ligands bind in a sequential manner, followed by another, slow conformational change on the time scale of seconds. This last step is more pronounced in the case of glycocholate (GCA), the bile salt that binds with high positive cooperativity and is absent in mutant I-BABP proteins that lack positive cooperativity in their bile salt binding.

Alternate binding mode of C-terminal phenethylamine analogs of G(t)alpha(340-350) to photoactivated rhodopsin.

The C-terminus of the Galpha-subunit of transducin plays an important role in receptor recognition. Synthetic peptides corresponding to the last 11 residues of the subunit have been shown to stabilize the photoactivated form of rhodopsin, Rh*. The Rh*-bound structure of the G(t)alpha(340-350) peptide has been determined using transferred nuclear overhauser effect NMR.

Relative strength of cation-pi vs salt-bridge interactions: the Gtalpha(340-350) peptide/rhodopsin system.

Interactions between cationic and aromatic side chains of amino acid residues, the so-called cation-pi interaction, are thought to contribute to the overall stability of the folded structure of peptides and proteins. The transferred NOE NMR structure of the G(t)alpha(340-350) peptide bound to photoactivated rhodopsin (R*) geometrically suggests a cation-pi interaction stabilizing the structure between the epsilon-amine of Lys341 and the aromatic ring of the C-terminal residue, Phe350. This interaction has been explored by varying substituents on the phenyl ring to alter the electron density of the aromatic ring of Phe350 and observing the impact on binding of the peptide to R*.

A faster migrating variant masquerades as NICD when performing in vitro gamma-secretase assays with bacterially expressed Notch substrates.

Intramembrane proteolysis is a new and rapidly growing field. In vitro assays utilizing recombinant substrates for gamma-secretase, an intramembrane-cleaving enzyme, are critically important in order to characterize the biochemical properties of this unusual enzyme. Several recombinant Notch proteins of varying length are commonly used as in vitro substrates for CHAPSO-solubilized gamma-secretase.

Analysis of ligand binding and protein dynamics of human retinoid X receptor alpha ligand-binding domain by nuclear magnetic resonance.

Retinoid X receptors (RXRs) are nuclear receptors that can activate transcription as homodimers or as obligate heterodimeric partners of other nuclear receptors. While the crystal structures of the RXR ligand-binding domains (LBD) have been previously determined, the dynamics of activation is less well characterized at an atomic level. To probe the effect of ligand binding on RXR LBD dynamics, we initiated nuclear magnetic resonance studies of recombinant human RXRalpha LBD (T223-T462) with and without bound 9-cis-retinoic acid (9cRA).

Determinants of cooperativity and site selectivity in human ileal bile acid binding protein.

Human ileal bile acid binding protein (I-BABP) is a member of the family of intracellular lipid-binding proteins and is thought to play a role in the enterohepatic circulation of bile salts. Our group has previously shown that human I-BABP binds two molecules of glycocholate (GCA) with low intrinsic affinity but an extraordinary high degree of positive cooperativity. Besides the strong positive cooperativity, human I-BABP exhibits a high degree of site selectivity in its interactions with GCA and glycochenodeoxycholate (GCDA), the two major bile salts in humans.

A single hydroxyl group governs ligand site selectivity in human ileal bile acid binding protein.

The recognition between proteins and their native ligands is fundamental to biological function. In vivo, human ileal bile acid binding protein (I-BABP) encounters a range of bile salts that vary in the number and position of steroidal hydroxyl groups and the presence and type of side-chain conjugation. Therefore, it is necessary to understand how chemical variability in the ligand affects the energetic and structural aspects of its recognition.

The NMR structure of a stable and compact all-beta-sheet variant of intestinal fatty acid-binding protein.

Intestinal fatty acid-binding protein (I-FABP) has a clam-shaped structure that may serve as a scaffold for the design of artificial enzymes and drug carriers. In an attempt to optimize the scaffold for increased access to the interior-binding cavity, several helix-less variants of I-FABP have been engineered. The solution-state NMR structure of the first generation helix-less variant, known as Delta17-SG, revealed a larger-than-expected and structurally ill-defined loop flanking the deletion site.

Steroid ring hydroxylation patterns govern cooperativity in human bile acid binding protein.

Human ileal bile acid binding protein (I-BABP) is a member of the intracellular lipid binding protein family. This protein is thought to function in the transcellular transport and enterohepatic circulation of bile salts. Human I-BABP binds two molecules of glycocholate, the physiologically most abundant bile salt, with modest intrinsic affinity but a remarkably high degree of positive cooperativity.

Measurement of methyl 13C-1H cross-correlation in uniformly 13C-, 15N-, labeled proteins.

An understanding of side chain motions in protein is of great interest since side chains often play an important role in protein folding and intermolecular interactions. A novel method for measuring the dynamics of methyl groups in uniformly 13C-, 15N-labeled proteins has been developed by our group. The method relies on the difference in peak intensities of 13C quartet components of methyl groups, in a spectrum recording the free evolution of 13C under proton coupling in a constant-time period.

Two homologous rat cellular retinol-binding proteins differ in local conformational flexibility.

Cellular retinol-binding protein I (CRBP I) and cellular retinol-binding protein II (CRBP II) are closely homologous proteins that play distinct roles in the maintenance of vitamin A homeostasis. The solution structure and dynamics of CRBP I and CRBP II were compared by multidimensional NMR techniques. These studies indicated that differences in the mean backbone structures of CRBP I and CRBP II were localized primarily to the alphaII helix.

An embryo-associated fatty acid-binding protein in the filarial nematode Brugia malayi.

Brugia malayi is a filarial nematode parasite that causes lymphatic filariasis, a disease that affects millions of people in the tropics. Sexual reproduction of filarial worms occurs within the lymphatic vessels of the human host and is crucial for transmission of the parasite to the mosquito vector. We have previously identified several B.

Synthesis of [3,4-(13)c(2)]-enriched bile salts as NMR probes of protein-ligand interactions.

Synthetic methodology that allows for incorporation of isotopic carbon at the C-3 and C-4 positions of bile salts is reported. Three [3,4-(13)C(2)]-enriched bile salts were synthesized from either deoxycholic or lithocholic acid. The steroid 3alpha-OH group was oxidized and the A-ring was converted into the Delta(4)-3-ketone.

Energetics by NMR: site-specific binding in a positively cooperative system.

Proteins with multiple binding sites exhibit a complex behavior that depends on the intrinsic affinities for each site and the energetic communication between the sites. The contributions from intrinsic affinity and cooperativity are difficult to deconvolute using conventional binding experiments that lack information about the occupancies of individual sites. Here, we report the concerted use of NMR and isothermal titration calorimetry to determine the intrinsic and cooperative binding free energies for a ligand-protein complex.