The effect of protein composition on hydration dynamics.

Water dynamics at the surface of two homologous proteins with different thermal resistances is found to be unaffected by the different underlying amino-acid compositions, and when proteins are folded it responds similarly to temperature variations. Upon unfolding the water dynamics slowdown with respect to bulk decreases by a factor of two. Our findings are explained by the dominant topological perturbation induced by the protein on the water hydrogen bond dynamics.

Effect of zinc salts on respiratory syncytial virus replication.

Zinc supplementation decreases the morbidity of lower respiratory tract infection in pediatric patients in the developing world. We sought to determine if zinc mediates a specific inhibitory effect against the major cause of pediatric lower respiratory tract disease, respiratory syncytial virus (RSV). We determined the in vitro inhibitory effect of three zinc salts (zinc acetate, lactate, and sulfate) on the replication of RSV at various concentrations of 10 and 1 mM and 100 and 10 microM. The degree of inhibition of RSV replication was examined in the presence of zinc during preincubation, adsorption, or penetration and was compared with that caused by salts of other divalent cations. Complete inhibition of RSV plaque formation was observed at 1 and 10 mM, representing reductions that were >or=10(6)-fold. At the lowest concentration tested, 10 microM, we observed >or=1000-fold reductions in RSV yield when zinc was present during preincubation, adsorption, penetration, or egress of virus. The therapeutic indices, determined as ratios of 50% toxicity concentration to 50% inhibitory concentration, were 100, 150, and 120 for zinc acetate, zinc lactate, and zinc sulfate, respectively. The inhibitory effect of zinc salts on RSV was concentration dependent and was not observed with other salts containing divalent cations such as calcium, magnesium, and manganese. RSV plaque formation was prevented by pretreatment of HEp-2 cell monolayer cultures with zinc or by addition of zinc to methylcellulose overlay media after infection. The results of this study suggest that zinc mediates antiviral activity on RSV by altering the ability of the cell to support RSV replication.

Unilateral facial paralysis occurring in an infant with enteroviral otitis media and aseptic meningitis.

We report the case of a four month old infant presenting to the Emergency Department (ED) with irritability and facial asymmetry following a recent bout of gastroenteritis. Physical examination revealed a unilateral peripheral facial nerve paralysis. Common in older children and adults, facial nerve palsy has rarely been described in infancy. Although historically associated with a variety of inflammatory and infectious causes, the pathogenesis remains unclear. In this infant we were able to successfully identify an underlying acute enteroviral infection. Coxsackie B5 was isolated from the middle ear fluid, cerebrospinal fluid (CSF), nasopharyngeal and rectal swabs. After myringotomy drainage of the middle ear fluid and placement of pneumatic equalization tubes, there was rapid and complete resolution of facial paralysis.