Mitochondria are best known as the essential intracellular organelles that host the homeostasis required for cellular survival, but they also have relevance in diverse disease-related conditions, including Alzheimer's disease (AD). Amyloid β (Aβ) peptide is the key molecule in AD pathogenesis, and has been highlighted in the implication of mitochondrial abnormality during the disease progress. Neuronal exposure to Aβ impairs mitochondrial dynamics and function. Furthermore, mitochondrial Aβ accumulation has been detected in the AD brain. However, the underlying mechanism of how Aβ affects mitochondrial function remains uncertain, and it is questionable whether mitochondrial Aβ accumulation followed by mitochondrial dysfunction leads directly to neuronal toxicity. This study demonstrated that an exogenous Aβ1–42 treatment, when applied to the hippocampal cell line of mice (specifically HT22 cells), caused a deleterious alteration in mitochondria in both morphology and function. A clathrin-mediated endocytosis blocker rescued the exogenous Aβ1–42-mediated mitochondrial dysfunction. Furthermore, the mitochondria-targeted accumulation of Aβ1–42 in HT22 cells using Aβ1–42 with a mitochondria-targeting sequence induced the identical morphological alteration of mitochondria as that observed in the APP/PS AD mouse model and exogenous Aβ1–42-treated HT22 cells. In addition, subsequent mitochondrial dysfunctions were demonstrated in the mitochondria-specific Aβ1–42 accumulation model, which proved indistinguishable from the mitochondrial impairment induced by exogenous Aβ1–42-treated HT22 cells. Finally, cellular toxicity was directly induced by mitochondria-targeted Aβ1–42 accumulation, which mimics the apoptosis process in exogenous Aβ1–42-treated HT22 cells. Taken together, these results indicate that mitochondria-targeted Aβ1–42 accumulation is the necessary and sufficient condition for Aβ-mediated mitochondria impairments, and leads directly to cellular death rather than along with other Aβ-mediated signaling alterations.

Cancer immunotherapy is a promising way to eliminate tumor cells by using the patient’s own immune system. Selecting the appropriate animal models to develop or validate preclinical immunotherapeutic trials is now an important aspect of many cancer research programs. Here we discuss the advantages and limitations of using genetically engineered immunodeficient mouse models, patient-derived xenografts (PDXs), and humanized mouse models for developing and testing immunotherapeutic strategies.

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by cognitive deficits, neuroinflammation, and loss of neurons. Recently, it has been shown that ghrelin, a 28 amino acid peptide hormone produced from the stomach and hypothalamus, has been reported as a potential therapeutic agent for several neurological disorders, including Parkinson's disease (PD), stroke, epilepsy, multiple sclerosis, and spinal cord injury. Here we determined the effects of ghrelin on memory impairments and neuropathological changes in an AD mouse model induced by intrahippocampal injection of amyloid-β oligomers (AβO). We report that ghrelin: 1) rescues memory deficits in mice injected with AβO in the hippocampus; 2) decreases AβO-induced microgliosis in hippocampus; 3) attenuates hippocampal neuronal loss mediated by AβO; 4) prevents AβO-associated synaptic degeneration including cholinergic fiber loss. Taken together, our findings demonstrate that ghrelin can ameliorate AβO-induced cognitive impairment associated with neuroinflammation and neuronal loss. These results suggest that ghrelin may be a promising therapeutic agent for the treatment of AD.

Background Azithromycin exposure has been reported to increase the risk of QT prolongation and cardiovascular death. However, findings on the association between azithromycin and cardiovascular death are controversial, and azithromycin is still used in actual practice. Additionally, quantitative assessments of risk have not been performed, including the risk of QT prolongation when patients are exposed to azithromycin in a real-world clinical setting. Therefore, in this study, we aimed to evaluate the risk of exposure to azithromycin on QT prolongation in a real-world clinical setting using a 21-year medical history database of a tertiary medical institution. Methods We analyzed the electrocardiogram results and relevant electronic health records of 402,607 subjects in a tertiary teaching hospital in Korea from 1996 to 2015. To evaluate the risk of QT prolongation of azithromycin, we conducted a case-control analysis using amoxicillin for comparison. Multiple logistic regression analysis was performed to correct for age, sex, accompanying drugs, and disease. Results The odds ratio (OR) for QT prolongation (QTc>450 ms in male and >460 ms in female) on azithromycin exposure was 1.40 (95% confidence interval [CI], 1.23-1.59), and the OR for severe QT prolongation (QTc>500 ms) was 1.43 (95% CI, 1.13-1.82). On the other hand, the ORs on exposure to amoxicillin were 1.06 (95% CI, 0.97-1.15) and 0.88 (95% CI, 0.70-1.09). In a subgroup analysis, the risk of QT prolongation in patients aged between 60 and 80 years was significantly higher when they are exposed to azithromycin. Conclusions The risk of QT prolongation was increased when patients, particularly the elderly aged 60-79 years, were exposed to azithromycin. Therefore, clinicians should pay exercise caution using azithromycin or consider using other antibiotics, such as amoxicillin, instead of azithromycin.

Mechanistic studies of the aromatic hydroxylation by high-valent iron(IV)-oxo porphyrin pi-cation radicals revealed that the aromatic oxidation involves an initial electrophilic attack on the pi-system of the aromatic ring to produce a tetrahedral radical or cationic sigma-complex. The mechanism was proposed on the basis of experimental results such as a large negative Hammett rho value and an inverse kinetic isotope effect. By carrying out isotope labeling studies, the oxygen in oxygenated products was found to derive from the iron-oxo porphyrin intermediates.