Intact olfactory memory in the 5xFAD mouse model of Alzheimer's disease from 3 to 15 months of age.

Alzheimer's disease (AD) is an age-related neurodegenerative disorder that causes profound cognitive dysfunction. Deficits in olfactory memory occur in early stages of AD and may be useful in AD diagnosis. The 5xFAD mouse is a commonly used model of AD, as it develops neuropathology, cognitive and sensori-motor dysfunctions similar to those seen in AD. However, olfactory memory dysfunction has not been studied adequately or in detail in 5xFAD mice. Furthermore, despite sex differences in AD prevalence and symptom presentation, few studies using 5xFAD mice have examined sex differences in learning and memory. Therefore, we tested olfactory memory in male and female 5xFAD mice from 3 to 15 months of age using a conditioned odour preference task. Olfactory memory was not impaired in male or female 5xFAD mice at any age tested, nor were there any sex differences. Because early-onset impairments in very long-term (remote) memory have been reported in 5xFAD mice, we trained a group of mice at 3 months of age and tested olfactory memory 90 days later. Very long-term olfactory memory in 5xFAD mice was not impaired, nor was their ability to perform the discrimination task with new odourants. Examination of brains from 5xFAD mice confirmed extensive Aß-plaque deposition spanning the olfactory memory system, including the olfactory bulb, hippocampus, amygdala and piriform cortex. Overall this study indicates that male and female 5xFAD mice do not develop olfactory memory deficits, despite extensive Aß deposition within the olfactory-memory regions of the brain.

Cardiac toxicity of the echinocandins: chance or cause and effect association?

WHAT IS KNOWN AND OBJECTIVE: Fungal infections pose a constant risk to critically ill and immunosuppressed patients. The echinocandin antifungals give practitioners an arsenal of agents with apparently lower toxicity relative to older agents. The objective of this commentary is to review the cardiac toxicity of the echinocandin antifungals in the light of recent evidence and published case reports. COMMENT: Three case reports detail cardiac decompensation following the initiation of anidulafungin and caspofungin and corroborate ex vivo laboratory results, in which rat hearts exposed to anidulafungin and caspofungin had significantly decreased cardiac contractility. Our hypothesized mechanism of toxicity of anidulafungin and caspofungin is mitochondrial toxicity. WHAT IS NEW AND CONCLUSION: The clinical corroboration of the ex vivo work presented above highly suggests that the cardiac toxicity seen with some of the echinocandin antifungals is a cause and effect pattern, not a chance finding.