The vascular endothelial cell mediates insulin transport into skeletal muscle.
AuthorsWang H, Liu Z, Li G, Barrett EJ,
JournalAm J Physiol Endocrinol Metab
PubMed ID16569759
'The pathways by which insulin exits the vasculature to muscle interstitium have not been characterized. In the present study, we infused FITC-labeled insulin to trace morphologically (using confocal immunohistochemical methods) insulin transport into rat skeletal muscle. We biopsied rectus muscle at 0, 10, 30, and 60 min after beginning a ... More
LXRbeta is required for adipocyte growth, glucose homeostasis, and beta cell function.
AuthorsGerin I, Dolinsky VW, Shackman JG, Kennedy RT, Chiang SH, Burant CF, Steffensen KR, Gustafsson JA, MacDougald OA
JournalJ Biol Chem
PubMed ID15831500
'Liver X receptors (LXR) alpha and beta are nuclear oxysterol receptors with established roles in cholesterol, lipid, and carbohydrate metabolism. Although LXRs have been extensively studied in liver and macrophages, the importance for development and metabolism of other tissues and cell types is not as well characterized. We demonstrate here ... More
Optical measurement of transverse molecular diffusion in a microchannel.
AuthorsKamholz AE, Schilling EA, Yager P
JournalBiophys J
PubMed ID11259309
'Quantitative analysis of molecular diffusion is a necessity for the efficient design of most microfluidic devices as well as an important biophysical method in its own right. This study demonstrates the rapid measurement of diffusion coefficients of large and small molecules in a microfluidic device, the T-sensor, by means of ... More
Total insulin and IGF-I resistance in pancreatic beta cells causes overt diabetes.
AuthorsUeki K, Okada T, Hu J, Liew CW, Assmann A, Dahlgren GM, Peters JL, Shackman JG, Zhang M, Artner I, Satin LS, Stein R, Holzenberger M, Kennedy RT, Kahn CR, Kulkarni RN
JournalNat Genet
PubMed ID16642022
'An appropriate beta cell mass is pivotal for the maintenance of glucose homeostasis. Both insulin and IGF-1 are important in regulation of beta cell growth and function (reviewed in ref. 2). To define the roles of these hormones directly, we created a mouse model lacking functional receptors for both insulin ... More
Flow cytofluorometric analysis of insulin binding and internalization by Swiss 3T3 cells.
AuthorsMurphy RF, Powers S, Verderame M, Cantor CR, Pollack R
JournalCytometry
PubMed ID6804197
'The binding of a fluorescein-isothiocyanate derivative of insulin to Swiss 3T3 cells was measured by flow cytometry. The kinetics of the subsequent internalization were also measured; at a concentration of 1 microM labeled insulin approximately 25% of the internalization was insulin-specific. The kinetics of endocytosis were contrasted to those of ... More
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for identifying the composition of labeled proteins.
AuthorsLu J, Zenobi R
JournalAnal Biochem
PubMed ID10222003
'Labeled proteins are extensively used in molecular biology and environmental science. The determination of the composition and label ratio is very important for monitoring the efficiency of their separation and purification. In this paper a novel method based on matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry was developed for this ... More
Smart hydrogel particles: biomarker harvesting: one-step affinity purification, size exclusion, and protection against degradation.
AuthorsLuchini A, Geho DH, Bishop B, Tran D, Xia C, Dufour RL, Jones CD, Espina V, Patanarut A, Zhou W, Ross MM, Tessitore A, Petricoin EF, Liotta LA,
JournalNano Lett
PubMed ID18076201
'Disease-associated blood biomarkers exist in exceedingly low concentrations within complex mixtures of high-abundance proteins such as albumin. We have introduced an affinity bait molecule into N-isopropylacrylamide to produce a particle that will perform three independent functions within minutes, in one step, in solution: (a) molecular size sieving, (b) affinity capture ... More
Receptor-ligand internalization.
AuthorsOrlandini G, Ronda N, Gatti R, Gazzola GC, Borghetti A
JournalMethods Enzymol
PubMed ID10506983
Insulin staining of ES cell progeny from insulin uptake.
AuthorsRajagopal J, Anderson WJ, Kume S, Martinez OI, Melton DA
JournalScience
PubMed ID12532008
Localization of analyte molecules in MALDI preparations by confocal laser scanning microscopy.
AuthorsHorneffer V, Forsmann A, Strupat K, Hillenkamp F, Kubitscheck U
JournalAnal Chem
PubMed ID11289411
In this study, the incorporation of Texas Red-labeled avidin into crystals of 2,5-dihydroxybenzoic acid (2,5-DHB) and 2,6-DHB (used as matrixes for matrix-assisted laser desorption/ionization (MALDI)) was investigated by fluorescence spectrophotometry and confocal laser scanning microscopy (CLSM). The analyte distribution in crystals, grown slowly under controlled conditions, was compared to the ... More
Serial immunoassays in parallel on a microfluidic chip for monitoring hormone secretion from living cells.
AuthorsDishinger JF, Kennedy RT
JournalAnal Chem
PubMed ID17263320
A microfluidic chip that allows for the continuous monitoring of cellular secretions from multiple independent living samples was developed. Performance of the device was characterized through the analysis of insulin secretion from islets of Langerhans. The chip contained four individual channel networks, each capable of performing electrophoresis-based immunoassays of the ... More
High-throughput automated post-processing of separation data.
AuthorsShackman JG, Watson CJ, Kennedy RT
JournalJ Chromatogr A
PubMed ID15230534
The development of an efficient method for high-throughput analysis of multiple electropherograms or chromatograms collected in series is presented. The method, encoded in a computer program designated "Cutter", utilizes batch processing for determining chromatographic figures of merit (CFOM) including peak centroid times, heights, areas, signal-to-noise ratios (S/N), variance (sigma2), skew, ... More
Microfluidic chip for continuous monitoring of hormone secretion from live cells using an electrophoresis-based immunoassay.
A microfluidic device has been developed for the determination of insulin secreted from islets of Langerhans by a capillary electrophoresis competitive immunoassay. Online assays were performed by electrophoretically sampling anti-insulin antibody (Ab), fluorescein isothiocyanate-labeled insulin (FITC-insulin), and insulin from separate reservoirs and allowing them to mix as they traveled through ... More
Synthesis and characterization of insulin-fluorescein derivatives for bioanalytical applications.
Human insulin was labeled with fluorescein isothiocyanate (FITC) and fully characterized to yield four distinct insulin-FITC species. High-performance liquid chromatography and electrospray mass spectrometry were used to determine the extent and location of fluorescein conjugation. By changing the reaction conditions (i.e., pH, time, and FITC/insulin ratio) the selectivity of the ... More
Perfusion and chemical monitoring of living cells on a microfluidic chip.
A microfluidic device that incorporates continuous perfusion and an on-line electrophoresis immunoassay was developed, characterized, and applied to monitoring insulin secretion from single islets of Langerhans. In the device, a cell chamber was perfused with cell culture media or a balanced salt solution at 0.6 to 1.5 microL min(-1). The ... More