Development of a quantitative, cell-line based assay to measure ADCC activity mediated by therapeutic antibodies.

Antibody-dependent cellular cytotoxicity (ADCC) contributes to clinical efficacy of a broad range of antibody therapeutics. However, reproducible quantitation of ADCC activity on a cellular level remains highly challenging, as ADCC assays rely on primary effector cells associated with laborious cell purification procedures, resulting in highly donor-dependent results. Here, we report the development of an in vitro ADCC method based on an engineered human natural killer cell line as effectors.

Enzyme molecular mechanism as a starting point to design new inhibitors: a theoretical study of O-GlcNAcase.

O-Glycoprotein 2-acetamino-2-deoxy-β-D-glucopyranosidase (O-GlcNAcase) hydrolyzes O-linked 2-acetamido-2-deoxy-β-D-glucopyranoside (O-GlcNAc) residues from post-translationally modified serine/threonine residues of nucleocytoplasmic protein. The chemical process involves substrate-assisted catalysis, where two aspartate residues have been identified as the two key catalytic residues of O-GlcNAcase. In this report, the first step of the catalytic mechanism used by O-GlcNAcase involving substrate-assisted catalysis has been studied using a hybrid quantum mechanical/molecular mechanical (QM/MM) Molecular Dynamics (MD) calculations.

Temperature dependence of the kinetic isotope effects in thymidylate synthase. A theoretical study.

In recent years, the temperature dependence of primary kinetic isotope effects (KIE) has been used as indicator for the physical nature of enzyme-catalyzed H-transfer reactions. An interactive study where experimental data and calculations examine the same chemical transformation is a critical means to interpret more properly temperature dependence of KIEs. Here, the rate-limiting step of the thymidylate synthase-catalyzed reaction has been studied by means of hybrid quantum mechanics/molecular mechanics (QM/MM) simulations in the theoretical framework of the ensemble-averaged variational transition-state theory with multidimensional tunneling (EA-VTST/MT) combined with Grote-Hynes theory.

Ataxia telangiectasia: a "disease model" to understand the cerebellar control of vestibular reflexes.

Experimental animal models have suggested that the modulation of the amplitude and direction of vestibular reflexes are important functions of the vestibulocerebellum and contribute to the control of gaze and balance. These critical vestibular functions have been infrequently quantified in human cerebellar disease. In 13 subjects with ataxia telangiectasia (A-T), a disease associated with profound cerebellar cortical degeneration, we found abnormalities of several key vestibular reflexes.

Vestibulo-cerebellar disease impairs the central representation of self-orientation.

Transformation of head-fixed otolith signals into a space-fixed frame of reference is essential for perception of self-orientation and ocular motor control. In monkeys the nodulus and ventral uvula of the vestibulo-cerebellum facilitate this transformation by computing an internal estimate of direction of gravity. These experimental findings motivated the hypothesis that degeneration of the vestibulo-cerebellum in humans alter perceptual and ocular motor functions that rely on accurate estimates of gravity, such as subjective visual vertical (SVV), static ocular counterroll (OCR), and gravity-dependent modulation of vertical ocular drifts.

Evidence summaries tailored to health policy-makers in low- and middle-income countries.

Objective: To describe how the SUPPORT collaboration developed a short summary format for presenting the results of systematic reviews to policy-makers in low- and middle-income countries (LMICs).

Methods: We carried out 21 user tests in six countries to explore users' experiences with the summary format. We modified the summaries based on the results and checked our conclusions through 13 follow-up interviews.

Biofilm formation at the solid-liquid and air-liquid interfaces by Acinetobacter species.

Background: The members of the genus Acinetobacter are Gram-negative cocobacilli that are frequently found in the environment but also in the hospital setting where they have been associated with outbreaks of nosocomial infections. Among them, Acinetobacter baumannii has emerged as the most common pathogenic species involved in hospital-acquired infections. One reason for this emergence may be its persistence in the hospital wards, in particular in the intensive care unit; this persistence could be partially explained by the capacity of these microorganisms to form biofilm.

First identification and characterization of an AdeABC-like efflux pump in Acinetobacter genomospecies 13TU.

Non-Acinetobacter baumannii spp. are emerging among clinical Acinetobacter isolates causing nosocomial infections, and some (such as genomospecies 13TU) appear to be multidrug resistant. The prevalence of non-Acinetobacter baumannii spp.

Head position during resting modifies spontaneous daytime decrease of downbeat nystagmus.

Background: The intensity of downbeat nystagmus (DBN) decreases during the daytime when the head is in upright position.

Objective: This prospective study investigated whether resting in different head positions (upright, supine, prone) modulates the intensity of DBN after resting.

Methods: Eye movements of 9 patients with DBN due to cerebellar (n = 2) or unknown etiology (n = 7) were recorded with video-oculography.

Velocity storage contribution to vestibular self-motion perception in healthy human subjects.

Self-motion perception after a sudden stop from a sustained rotation in darkness lasts approximately as long as reflexive eye movements. We hypothesized that, after an angular velocity step, self-motion perception and reflexive eye movements are driven by the same vestibular pathways. In 16 healthy subjects (25-71 years of age), perceived rotational velocity (PRV) and the vestibulo-ocular reflex (rVOR) after sudden decelerations (90°/s(2)) from constant-velocity (90°/s) earth-vertical axis rotations were simultaneously measured (PRV reported by hand-lever turning; rVOR recorded by search coils).

Effect of 4-aminopyridine on gravity dependence and neural integrator function in patients with idiopathic downbeat nystagmus.

Downbeat nystagmus (DBN) is a frequent sign in patients with cerebellar degeneration. It consists of an upward drift of the eye that does not depend on vertical head position (spontaneous drift, SD), a gravity-dependent component (GD), and a gaze-evoked drift reflecting gaze-holding impairment (deficient neural integrator function). The potassium-channel blocker 4-aminopyridine (4-AP) is reported to reduce DBN in patients with cerebellar atrophy but with little or no effect in patients with idiopathic DBN.

Estimation of the burden of cardiovascular disease attributable to modifiable risk factors and cost-effectiveness analysis of preventative interventions to reduce this burden in Argentina.

Background: Cardiovascular disease (CVD) is the primary cause of mortality and morbidity in Argentina representing 34.2% of deaths and 12.6% of potential years of life lost (PYLL).

Health technology assessment for resource allocation decisions: are key principles relevant for Latin America?

Objectives: A set of fifteen key principles (KP) has been recently proposed to guide decisions on the structure of HTA programs, the methods of HTA, the processes for conducting HTA and the use of HTA findings in decision-making. The objective of this research is to explore whether these KPs are relevant and useful in Latin America (LA), and to what extent they are being applied.

Methods: A Web-based survey was sent to 11,792 HTA researchers and users in LA to explore the perceived relevance of each KP, its current level of application and the gap between these two.

Application of Grote-Hynes theory to the reaction catalyzed by thymidylate synthase.

A theoretical study of dynamic effects on the rate-limiting step of the thymidylate synthase catalyzed reaction has been carried out by means of Grote-Hynes theory, successfully predicting the values of the recrossing effects for a chemical reaction that involves the transfer of a classical light particle. The transmission coefficients, obtained at 278, 293, 303, and 313 K, are almost invariant and in all cases far from unity, revealing a significant coupling of the environment motions and the reaction coordinate. Nevertheless, their energetic contribution to the activation free energy represents less than 0.

Predicting nocturnal hypoventilation in hypercapnic chronic obstructive pulmonary disease patients undergoing long-term oxygen therapy.

Background: Chronic obstructive pulmonary disease (COPD) patients are very sensitive to changes in pulmonary mechanics and central ventilation control during sleep and may develop significant gas exchange alterations with increased hypoxemia and hypercapnia. Oxygen therapy improves nocturnal desaturation but can worsen hypoventilation.

Objectives: To analyze the prevalence of nocturnal hypoventilation (NHV) in hypercapnic COPD patients and to determine predictive factors for this phenomenon.

Predictors of mortality in chest wall disease treated with noninvasive home mechanical ventilation.

Rationale: The long-term evolution of patients with chest wall disease and chronic respiratory failure treated with noninvasive home mechanical ventilation (NIHMV) is poorly known.

Objectives: The aim of this prospective observational study was to analyze the variables associated with mortality in a cohort of chest wall disease patients with chronic respiratory failure undergoing long-term follow-up after starting treatment with NIHMV.

Methods: Chest wall disease patients who began NIHMV between 1996 and 2005 were followed up, with death as the primary outcome.

Economic evaluations on cardiovascular preventive interventions in Argentina.

Cardiovascular diseases are the main cause of death in Argentina. This article analyzes economic evaluations on cardiovascular prevention for this country. A literature search was conducted in five electronic databases during December 2009.

Theoretical study of the temperature dependence of dynamic effects in thymidylate synthase.

A theoretical study of the temperature dependence of dynamic effects in the rate limiting step of the reaction catalyzed by thymidylate synthase is presented in this paper. From hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) optimizations of transition state structures within a fully flexible molecular model, free downhill molecular dynamics trajectories have been performed at four different temperatures. The analysis of the reactive and non-reactive trajectories in the enzyme environment has allowed us to study the geometric and electronic coupling between the substrate, the cofactor and the protein.

Theoretical QM/MM studies of enzymatic pericyclic reactions.

The chorismate to prephenate enzyme catalyzed reaction has been used in this review as the conduit to show different theoretical approaches that have been used over the years in our laboratory to explain its molecular mechanism. This pericyclic reaction has the advantage that other protein scaffolds such as catalytic antibodies or some promiscuous enzymes present certain chorismate mutase activity. The obtained results on all these protein environments, by comparison with the uncatalyzed reaction in solution, have been used to propose, as a general conclusion, that the origin of enzyme catalysis is in the relative electrostatic stabilization of the transition state with respect to the Michaelis complex.

Quantum mechanical/molecular mechanical molecular dynamics simulation of wild-type and seven mutants of CpNagJ in complex with PUGNAc.

The enzyme O-glycoprotein 2-acetamino-2-deoxy-beta-d-glucopyranosidase (O-GlcNAcase) is responsible for the removal of N-acetylglucosamine moieties from 2-acetamido-2-deoxy-beta-D-glucopyranose (O-GlcNAc) residues of serine/threonine residues of modified proteins. We herein present results of hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations applied to the study of the interactions established between a bacterial Clostridium perfringens homologue (CpNagJ) and PUGNAc, a potent known inhibitor of this enzyme. Electrostatic binding free energy and energy term decomposition have been computed for the wild-type CpNagJ and several mutants: D297N, D298N, Y335F, N390A, N396A, D401A, and W490A.

Effects of ring castration with local anesthesia and analgesia in Holstein calves at 3 months of age on welfare indicators.

Forty-seven Holstein calves (130 +/- 3.43 kg of BW and 95 +/- 1.5 d of age) were randomly assigned to 2 treatments [intact (INT), n = 23; or castrated (CAS), n = 24] to evaluate the effect of ring castration at 3 mo of age on welfare indicators.

Mapping introspection's blind spot: reconstruction of dual-task phenomenology using quantified introspection.

Psychologists often dismiss introspection as an inappropriate measure, yet subjects readily volunteer detailed descriptions of the time and effort that they spent on a task. Are such reports really so inaccurate? We asked subjects to perform a psychological refractory period experiment followed by extensive quantified introspection. On each trial, just after their objective responses, subjects provided no less than four subjective estimates of the timing of sensory, decision and response events.

Sleep hypoventilation due to increased nocturnal oxygen flow in hypercapnic COPD patients.

Unlabelled: This study shows the risks and benefits of increasing the nocturnal oxygen flow in hypercapnic COPD patients undergoing LTOT, as recommended by some COPD treatment guidelines to avoid nocturnal desaturation.

Background And Objective: Several COPD treatment guidelines recommend increasing oxygen flow during sleep to avoid nocturnal desaturation. However, such an increase could have deleterious clinical and gas exchange effects.

Toward Understanding the Photochemistry of Photoactive Yellow Protein: A CASPT2/CASSCF and Quantum Theory of Atoms in Molecules Combined Study of a Model Chromophore in Vacuo.

Photochemical processes that take place in biological molecules have become an increasingly important research topic for both experimentalists and theoreticians. In this work, we report the reaction mechanism of a model of the photoactive yellow protein (PYP) chromophore in vacuo. The results obtained here, using a strategy based on the simultaneous use of the minimum energy path concept and the quantum theory of atoms in molecules applied to this excited state process, suggest a possible way in which the protein could increase the efficiency of the reaction.