Effect of Freezing and Thawing on Uptake of Amino Acids into Human Erythrocytes

ABSTRACT - The transport of C-amino acids into human erythrocytes and into erythrocytes which had been frozen and thawed was studied experimentally. The relative rates of uptake were found to be (in decreasing order): phenylalanine, leucine, alanine, trythophan, and glycine. Freezing (using gycerol as the cryoprotective additive) and thawing had no significant effect on either the magnitude of the rate constants or on the order of the above relative rates of amino acid uptake into erythrocytes suspended in isotonic TRIS-HCl buffer

Adsorption of proteins to thin-films of PDMS and its effect on the adhesion of human endothelial cells

This paper describes a simple and inexpensive procedure to produce thin-films of poly(dimethylsiloxane). Such films were characterized by a variety of techniques (ellipsometry, nuclear magnetic resonance, atomic force microscopy, and goniometry) and used to investigate the adsorption kinetics of three model proteins (fibrinogen, collagen type-I, and bovine serum albumin) under different conditions. The information collected from the protein adsorption studies was then used to investigate the adhesion of human dermal microvascular endothelial cells. The results of these studies suggest that these films can be used to model the surface properties of microdevices fabricated with commercial PDMS. Moreover, the paper provides guidelines to efficiently attach cells in BioMEMS devices.Fil: Chumbimuni Torres, Karin Y.. The University of Texas at San Antonio; Estados UnidosFil: Coronado, Ramon E.. The University of Texas at San Antonio; Estados UnidosFil: Mfuh, Adelphe M.. The University of Texas at San Antonio; Estados UnidosFil: Castro Guerrero, Carlos. The University of Texas at San Antonio; Estados UnidosFil: Silva, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Negrete, George R.. The University of Texas at San Antonio; Estados UnidosFil: Bizios, Rena. The University of Texas at San Antonio; Estados UnidosFil: Garcia, Carlos D.. The University of Texas at San Antonio; Estados Unido

Integration and fusion of standard automated perimetry and optical coherence tomography data for improved automated glaucoma diagnostics

<p>Abstract</p> <p>Background</p> <p>The performance of glaucoma diagnostic systems could be conceivably improved by the integration of functional and structural test measurements that provide relevant and complementary information for reaching a diagnosis. The purpose of this study was to investigate the performance of data fusion methods and techniques for simple combination of Standard Automated Perimetry (SAP) and Optical Coherence Tomography (OCT) data for the diagnosis of glaucoma using Artificial Neural Networks (ANNs).</p> <p>Methods</p> <p>Humphrey 24-2 SITA standard SAP and StratusOCT tests were prospectively collected from a randomly selected population of 125 healthy persons and 135 patients with glaucomatous optic nerve heads and used as input for the ANNs. We tested commercially available standard parameters as well as novel ones (fused OCT and SAP data) that exploit the spatial relationship between visual field areas and sectors of the OCT peripapillary scan circle. We evaluated the performance of these SAP and OCT derived parameters both separately and in combination.</p> <p>Results</p> <p>The diagnostic accuracy from a combination of fused SAP and OCT data (95.39%) was higher than that of the best conventional parameters of either instrument, i.e. SAP Glaucoma Hemifield Test (p < 0.001) and OCT Retinal Nerve Fiber Layer Thickness ≥ 1 quadrant (p = 0.031). Fused OCT and combined fused OCT and SAP data provided similar Area under the Receiver Operating Characteristic Curve (AROC) values of 0.978 that were significantly larger (p = 0.047) compared to ANNs using SAP parameters alone (AROC = 0.945). On the other hand, ANNs based on the OCT parameters (AROC = 0.970) did not perform significantly worse than the ANNs based on the fused or combined forms of input data. The use of fused input increased the number of tests that were correctly classified by both SAP and OCT based ANNs.</p> <p>Conclusions</p> <p>Compared to the use of SAP parameters, input from the combination of fused OCT and SAP parameters, and from fused OCT data, significantly increased the performance of ANNs. Integrating parameters by including a priori relevant information through data fusion may improve ANN classification accuracy compared to currently available methods.</p

Presence of functionally active protease-activated receptors 1 and 2 in myenteric glia

Protease-activated receptors (PARs) belong to the family of membrane receptors coupled to G-proteins; their presence is reported in a wide variety of cells. The object of this study was to demonstrate the presence of PAR-1 and PAR-2 in myenteric glia of the guinea pig, and to elucidate the cellular mechanisms that are triggered upon receptor activation. Thrombin and PAR-1 agonist peptide (PARP-1) activate PAR-1 with a maximum mean ± SEM change in intracellular calcium concentration with respect to basal level (δ[Ca 2+ ] i ) of 183 ± 18 nm and 169 ± 6 nm, respectively. Trypsin and PAR-2 agonist peptide (PARP-2) activate PAR-2 with a maximum δ[Ca 2+ ] i of 364 ± 28 nm and 239 ± 19 nm, respectively. Inhibition of phospholipase C by U73312 (1 µm) decreased the δ[Ca 2+ ] i due to PAR-1 activation from 167 ± 10 nm to 87 ± 6 nm. The PAR-2-mediated δ[Ca 2+ ] i decreased from 193 ± 10 nm to 124 ± 8 nm when phospholipase C activity was inhibited. Blockade of sphingosine kinase with dimethylsphingosine (1 µm) decreased the δ[Ca 2+ ] i due to PAR-2 activation from 149 ± 19 nm to 67 ± 1 nm, but did not influence the PAR-1-mediated δ[Ca 2+ ] i . PAR-1 and PAR-2 were localized in myenteric glia by immunolabeling. Our results indicate that PAR-1 and PAR-2 are present in myenteric glia of the guinea pig, and their activation leads to increases in intracellular calcium via different signal transduction mechanisms that involve activation of phospholipase C and sphingosine kinase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66037/1/j.1471-4159.2002.01119.x.pd

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Machine Learning Algorithms for Improved Glaucoma Diagnosis

Primary open angle glaucoma, one of the leading causes of blindness in the world, constitutes a slow progressing condition characterized by damage to the optic nerve and retinal nerve fibre layer, and results in visual field defects afflicting the visual function. Highly specific and sensitive diagnostic tests able to detect the clinically significant glaucomatous changes in the structure of the nerve fiber layer and visual field are therefore required for the early detection and management of this disease. This thesis treats the application of advanced statistical techniques based on machine learning for automated classification of tests from visual field examinations and retinal nerve fibre measurements to detect glaucoma. Diagnostic performance of the applied machine learning classification algorithms was shown to depend primarily on the type of test information that was provided. Optimized parameters from standard automated perimetry tests and OCT measurements of the nerve fibre layer derived from statistical processing to highlight statistically significant functional and structural changes, led to improvements in diagnostic accuracy. Moreover, the combination of structural and functional test information through incorporation of á priori knowledge about the anatomical relationship of the retinal nerve fibre layer and the visual field further increased the diagnostic performance of the automated classification algorithms. Machine Learning Classifiers based on optimized test input data could become useful decision support tools for more accurate glaucoma diagnosis