Predicting a double mutant in the twilight zone of low homology modeling for the skeletal muscle voltage-gated sodium channel subunit beta-1 (Nav1.4 β1)

The molecular structure modeling of the β1 subunit of the skeletal muscle voltage-gated sodium channel (Nav1.4) was carried out in the twilight zone of very low homology. Structural significance can per se be confounded with random sequence similarities. Hence, we combined (i) not automated computational modeling of weakly homologous 3D templates, some with interfaces to analogous structures to the pore-bearing Nav1.4 α subunit with (ii) site-directed mutagenesis (SDM), as well as (iii) electrophysiological experiments to study the structure and function of the β1 subunit. Despite the distant phylogenic relationships, we found a 3D-template to identify two adjacent amino acids leading to the long-awaited loss of function (inactivation) of Nav1.4 channels. This mutant type (T109A, N110A, herein called TANA) was expressed and tested on cells of hamster ovary (CHO). The present electrophysiological results showed that the double alanine substitution TANA disrupted channel inactivation as if the β1 subunit would not be in complex with the α subunit. Exhaustive and unbiased sampling of “all β proteins” (Ig-like, Ig) resulted in a plethora of 3D templates which were compared to the target secondary structure prediction. The location of TANA was made possible thanks to another “all β protein” structure in complex with an irreversible bound protein as well as a reversible protein–protein interface (our “Rosetta Stone” effect). This finding coincides with our electrophysiological data (disrupted β1-like voltage dependence) and it is safe to utter that the Nav1.4 α/β1 interface is likely to be of reversible nature

International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module

We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN