A causal relationship between hearing loss and cognitive impairment.

CONCLUSION: Moderate hearing loss in young mice caused decreases in cognition associated with spatial working and recognition memories in 6 months. These results provide evidence for a causal relationship between hearing loss and cognitive impairment. OBJECTIVES: Hypothesized mechanisms to connect sensory and cognitive functions include the sensory-deprivation, information-degradation, and common-cause hypotheses. This study intended to investigate the effect of hearing loss on cognitive function, as estimated by radial arm maze (RAM) and novel object recognition (NOR) tasks in mice through age- and hearing-matched longitudinal work during a 6-month period. METHODS: Twenty-four male C57BL/6 mice aged 1 month with normal ABR thresholds were used. Twelve mice in the hearing loss (HL) group were exposed to white noise at 110 dB SPL for 60 min every day for 20 days. At post-noise 6 months, all mice underwent RAM and one-trial NOR test. RAM performance measures and NOR discrimination index were compared between two groups. RESULTS: At 6 months after noise exposure, all mice in the experimental group had moderate hearing loss. Most of the RAM performances improved gradually within each group across five trials, probably due to learning effect. The HL group showed lower performance scores than the control group in several trial points in the RAM task. The contact time with the novel object was shorter in the HL group than in the control group.

A Novel Recombinant Enterovirus Type EV-A89 with Low Epidemic Strength in Xinjiang, China.

Enterovirus A89 (EV-A89) is a novel member of the EV-A species. To date, only one full-length genome sequence (the prototype strain) has been published. Here, we report the molecular identification and genomic characterization of a Chinese EV-A89 strain, KSYPH-TRMH22F/XJ/CHN/2011, isolated in 2011 from a contact of an acute flaccid paralysis (AFP) patient during AFP case surveillance in Xinjiang China. This was the first report of EV-A89 in China. The VP1 coding sequence of this strain demonstrated 93.2% nucleotide and 99.3% amino acid identity with the EV-A89 prototype strain. In the P2 and P3 regions, the Chinese EV-A89 strain demonstrated markedly higher identity than the prototype strains of EV-A76, EV-A90, and EV-A91, indicating that one or more recombination events between EV-A89 and these EV-A types might have occurred. Long-term evolution of these EV types originated from the same ancestor provides the spatial and temporal circumstances for recombination to occur. An antibody sero-prevalence survey against EV-A89 in two Xinjiang prefectures demonstrated low positive rates and low titres of EV-A89 neutralization antibody, suggesting limited range of transmission and exposure to the population. This study provides a solid foundation for further studies on the biological and pathogenic properties of EV-A89.