2,165 research outputs found
Molecular approaches to diagnosing and managing infectious diseases: practicality and costs.
As molecular techniques for identifying and detecting microorganisms in the clinical microbiology laboratory have become routine, questions about the cost of these techniques and their contribution to patient care need to be addressed. Molecular diagnosis is most appropriate for infectious agents that are difficult to detect, identify, or test for susceptibility in a timely fashion with conventional methods
Sub-gap spectroscopy of thermally excited quasiparticles in a Nb contacted carbon nanotube quantum dot
We present electronic transport measurements of a single wall carbon nanotube
quantum dot coupled to Nb superconducting contacts. For temperatures comparable
to the superconducting gap peculiar transport features are observed inside the
Coulomb blockade and superconducting energy gap regions. The observed
temperature dependence can be explained in terms of sequential tunneling
processes involving thermally excited quasiparticles. In particular, these new
channels give rise to two unusual conductance peaks at zero bias in the
vicinity of the charge degeneracy point and allow to determine the degeneracy
of the ground states involved in transport. The measurements are in good
agreement with model calculations.Comment: 5 pages, 4 figure
Amino acid incorporation into mitochondrial ribosomes of Neurospora crassa wild-type and Mi-1 mutant
Biogenesis of mitochondrial porin
We review here the present knowledge about the pathway of import and assembly of porin into mitochondria and compare it to those of other mitochondrial proteins. Porin, like all outer mitochondrial membrane proteins studied so far is made as a precursor without a cleavble lsquosignalrsquo sequence; thus targeting information must reside in the mature sequence. At least part of this information appears to be located at the amino-terminal end of the molecule. Transport into mitochondria can occur post-translationally. In a first step, the porin precursor is specifically recognized on the mitochondrial surface by a protease sensitive receptor. In a second step, porin precursor inserts partially into the outer membrane. This step is mediated by a component of the import machinery common to the import pathways of precursor proteins destined for other mitochondrial subcompartments. Finally, porin is assembled to produce the functional oligomeric form of an integral membrane protein wich is characterized by its extreme protease resistance
Automatic Mapping of Atrial Fiber Orientations for Patient-Specific Modeling of Cardiac Electromechanics using Image-Registration
Knowledge of appropriate local fiber architecture is necessary to simulate
patient-specific electromechanics in the human heart. However, it is not yet
possible to reliably measure in-vivo fiber directions, especially in human
atria. Thus, we present a method which defines the fiber architecture in
arbitrarily shaped atria using image registration and reorientation methods
based on atlas atria with fibers predefined from detailed histological
observations. Thereby, it is possible to generate detailed fiber families in
every new patient-specific geometry in an automated, time-efficient process. We
demonstrate the good performance of the image registration and fiber definition
on ten differently shaped human atria. Additionally, we show that
characteristics of the electrophysiological activation pattern which appear in
the atlas atria also appear in the patients' atria. We arrive at analogous
conclusions for coupled electro-mechano-hemodynamical computations
Mitochondrial precursor proteins are imported through a hydrophilic membrane environment
We have analyzed how translocation intermediates of imported mitochondrial precursor proteins, which span contact sites, interact with the mitochondrial membranes. F1-ATPase subunit β(F1β) was trapped at contact sites by importing it into Neurospora mitochondria in the presence of low levels of nucleoside triphosphates. This F1β translocation intermediate could be extracted from the membranes by treatment with protein denaturants such as alkaline pH or urea. By performing import at low temperatures, the ADP/ATP carrier was accumulated in contact sites of Neurospora mitochondria and cytochrome b2 in contact sites of yeast mitochondria. These translocation intermediates were also extractable from the membranes at alkaline pH. Thus, translocation of precursor proteins across mitochondrial membranes seems to occur through an environment which is accessible to aqueous perturbants. We propose that proteinaceous structures are essential components of a translocation apparatus present in contact sites
The trend of susceptibilities to amphotericin B and fluconazole of Candida species from 1999 to 2002 in Taiwan
BACKGROUND: Candida species have various degrees of susceptibility to common antifungal drugs. The extent of resistance to amphotericin B and fluconazole of Candida glabrata isolates causing candidemia has been reported. Active surveillance may help us to monitor the trend of susceptibility to antifungal drugs and to determine if there is an emerging co-resistance to both drugs of Candida species, specifically, of C. glabrata in Taiwan. METHODS: The susceptibilities to amphotericin B and fluconazole of Candida species collected in 1999 and 2002 of the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) were determined by the microdilution method. RESULTS: The antifungal susceptibilities of 342 and 456 isolates collected from 11 hospitals participating in both TSARY 1999 and TSARY 2002, respectively, have been determined. The resistance rate to amphotericin B has increased from 0.3% in the TSARY1999 to 2.2% in the TSARY 2002. In contrast, the resistance rate to fluconazole has decreased from 8.8% to 2.2%. Nevertheless, significantly more C. glabrata isolates were not susceptible to fluconazole in the TSARY 2002 (47.4%) than that in the TSARY 1999 (20.8%). There were 9.8% and 11% of C. glabrata isolates having susceptible-dose dependent and resistant phenotype to fluconazole in the TSARY 1999, verse 45.3% and 2.1% in the TSARY 2002. CONCLUSION: There was an increase of resistance rate to amphotericin B in C. glabrata. On the other hand, although the resistance rate to fluconazole has decreased, almost half of C. glabrata isolates were not susceptible to this drug. Hence, continuous monitoring the emerging of co-resistance to both amphotericin B and fluconazole of Candida species, specifically, of C. glabrata, will be an important early-warning system
A homogenized constrained mixture model of cardiac growth and remodeling: Analyzing mechanobiological stability and reversal
Cardiac growth and remodeling (G&R) patterns change ventricular size, shape,
and function both globally and locally. Biomechanical, neurohormonal, and
genetic stimuli drive these patterns through changes in myocyte dimension and
fibrosis. We propose a novel microstructure-motivated model that predicts
organ-scale G&R in the heart based on the homogenized constrained mixture
theory. Previous models, based on the kinematic growth theory, reproduced
consequences of G&R in bulk myocardial tissue by prescribing the direction and
extent of growth but neglected underlying cellular mechanisms. In our model,
the direction and extent of G&R emerge naturally from intra- and extra cellular
turnover processes in myocardial tissue constituents and their preferred
homeostatic stretch state. We additionally propose a method to obtain a
mechanobiologically equilibrated reference configuration. We test our model on
an idealized 3D left ventricular geometry and demonstrate that our model aims
to maintain tensional homeostasis in hypertension conditions. In a stability
map, we identify regions of stable and unstable G&R from an identical parameter
set with varying systolic pressures and growth factors. Furthermore, we show
the extent of G&R reversal after returning the systolic pressure to baseline
following stage 1 and 2 hypertension. A realistic model of organ-scale cardiac
G&R has the potential to identify patients at risk of heart failure, enable
personalized cardiac therapies, and facilitate the optimal design of medical
devices
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