Targeting vulnerable microcircuits in the ventral hippocampus of male transgenic mice to rescue Alzheimer-like social memory loss

BACKGROUND

Episodic memory loss is a prominent clinical manifestation of Alzheimer's disease (AD), which is closely related to tau pathology and hippocampal impairment. Due to the heterogeneity of brain neurons, the specific roles of different brain neurons in terms of their sensitivity to tau accumulation and their contribution to AD-like social memory loss remain unclear. Therefore, further investigation is necessary.

METHODS

We investigated the effects of AD-like tau pathology by Tandem mass tag proteomic and phosphoproteomic analysis, social behavioural tests, hippocampal electrophysiology, immunofluorescence staining and in vivo optical fibre recording of GCaMP6f and iGABASnFR. Additionally, we utilized optogenetics and administered ursolic acid (UA) via oral gavage to examine the effects of these agents on social memory in mice.

RESULTS

The results of proteomic and phosphoproteomic analyses revealed the characteristics of ventral hippocampal CA1 (vCA1) under both physiological conditions and AD-like tau pathology. As tau progressively accumulated, vCA1, especially its excitatory and parvalbumin (PV) neurons, were fully filled with mislocated and phosphorylated tau (p-Tau). This finding was not observed for dorsal hippocampal CA1 (dCA1). The overexpression of human tau (hTau) in excitatory and PV neurons mimicked AD-like tau accumulation, significantly inhibited neuronal excitability and suppressed distinct discrimination-associated firings of these neurons within vCA1. Photoactivating excitatory and PV neurons in vCA1 at specific rhythms and time windows efficiently ameliorated tau-impaired social memory. Notably, 1 month of UA administration efficiently decreased tau accumulation via autophagy in a transcription factor EB (TFEB)-dependent manner and restored the vCA1 microcircuit to ameliorate tau-impaired social memory.

CONCLUSION

This study elucidated distinct protein and phosphoprotein networks between dCA1 and vCA1 and highlighted the susceptibility of the vCA1 microcircuit to AD-like tau accumulation. Notably, our novel findings regarding the efficacy of UA in reducing tau load and targeting the vCA1 microcircuit may provide a promising strategy for treating AD in the future.

Refinement of nanoporous copper by dealloying the Al-Cu alloy in NaOH solution containing sodium dodecyl sulfate

This work reports the refinement of nanoporous copper (NPC) ligaments by introducing the sodium dodecyl sulfate (SDS) surfactant in the dealloying process. The Al₈₀Cu₂₀ (at%) alloy precursor is chemically dealloyed in a mixed solution of NaOH and SDS surfactant, producing NPC with a hierarchical microstructure. Micron-scaled skeletons that build up higher level networks consist of geometrically similar nano-scaled bi-continuous ligament-pore networks at the lower level. It has been found that the size of the ligaments in the lower level networks reduces from ∼32 nm to ∼24 nm with increasing SDS concentration to 1 mM. Further increasing the SDS concentration to 5 mM only leads to a slight ligament size decrease to ∼21 nm. Remarkably, nano-sized cones are formed on the lower level network surface in the dealloying solution containing 1 mM SDS, and the cone number greatly rises when the SDS concentration increases to 5 mM. The surface diffusivity of Cu adatoms is evaluated based on the experimental data, and the refinement of the ligament as well as the formation of cones are associated with the decreased surface diffusivity and the retarded Cu adatom motions with the addition of SDS. Quantum chemical calculations and molecular dynamics simulations are performed to model the adsorption behavior of SDS. It has been found that the SDS-substrate interaction increases with the number of SDS molecules before SDS reaches saturation.

[Comparison and reflection of standardization of public health management system both at home and abroad]

Objective: To better promote the standardization of public health management in China, and provide evidence for the development and improvement of the standardization strategy and management system in public health field in China. Methods: This paper summarizes and analyzes the information about the standardized management mechanism collected from international organizations related with standardization in public health. Results: The standards in public health varied in different management systems of the international organizations, and there were great differences in organization nature, standard types, application, release, organization structure, standard development principles, advantages, transformation, promotion and implementation, and evaluation. Conclusion: China can benefit from the studying of the working mechanism of the international organization related with standardization in public health to facilitate its own standardization in public health.

Mode-dependent effect of high-frequency electrical stimulation of the anterior thalamic nucleus on amygdala-kindled seizures in rats

Deep brain stimulation (DBS) is an emerging treatment of epilepsy. Anterior nucleus of the thalamus (ANT) is considered to be an attractive target due to its close connection to the limbic structures and wide regions of neocortex. The present study aimed to investigate the effects of high frequency stimulation (HFS) targeting the ANT on amygdala-kindled seizures in Wistar rats in two different stimulation modes i.e. pre-treatment and post-treatment stimulations, mimicking the scheduled and responsive stimulations in clinical use respectively. When fully-kindled seizures were achieved by daily amygdala kindling (1 s train of 1 ms pulses at 60 Hz), HFS (15 min train of 100 μs pulses at 150 Hz and 450-800 μA) was applied in two modes for 10 days. Bilateral post-treatment with HFS reduced the incidence of generalized seizures and the mean behavioral seizure stage and shortened average afterdischarge duration (ADD) and generalized seizure duration (GSD), while bilateral pre-treatment with HFS resulted in a similar but much weaker inhibition of seizures. On the other hand, we also found the two stimulation modes both increased the afterdischarge threshold (ADT) and the differences of current intensity between ADT and generalized seizure threshold (GST) i.e. Δ(GST-ADT). However, Δ(GST-ADT) increased by at least 20 μA in bilateral post-treatment group, while less in bilateral pre-treatment group. Additionally, unilateral post-treatment with HFS failed to inhibit seizures. Our data show that anti-epileptic effect of bilateral post-treatment with HFS of ANT is much stronger than that of bilateral pre-treatment HFS, indicating bilateral responsive stimulation might be more appropriate for clinical anti-epileptic treatment of ANT HFS.

A preliminary study of apparent diffusion coefficient in chemotherapy-induced liver damage

OBJECTIVES

To investigate changes in the hepatic apparent diffusion coefficient (ADC) in patients undergoing chemotherapy.

METHODS

We enrolled 54 patients (25 women; mean age 57.0±13.1 years, range 29-89 years) undergoing chemotherapy for tumor and 10 controls (7 women; mean age 55.1±17.5 years, range 23-81 years). The patients were tested for serum alanine aminotransferase (ALT) activity (abnormal, normal) and fatty liver. Hepatic ADC values were compared among controls, patients and subgroups. Pearson correlation coefficient was used to assess the correlation between ADC and ALT activity.

RESULTS

Hepatic ADC0,850 (×10(-3) mm2/s) was lower for patients than controls (1.14±0.18 vs. 1.28±0.12, P=0.02) and was lower for patients with than without fatty liver and controls (1.01±0.06 vs. 1.18±0.18 and 1.28±0.12, respectively, all P<0.01), with no significant difference between patients without fatty liver and controls (P=0.07). ADC0,850 was lower for patients with abnormal ALT than normal ALT activity and controls (0.99±0.06 vs. 1.17±0.18 and 1.28±0.12, respectively, all P<0.05), with a significant difference also being seen between patients with normal ALT activity and controls (P=0.04). Hepatic ADC0,850 was not correlated with ALT activity in patients (r=-0.24, P=0.08).

CONCLUSIONS

Although ADC did not correlate with ALT values, it did distinguish patient likely to have chemotherapy-induced liver damage as indicated by abnormal ALT values or fatty liver. These mechanisms need to be disentangled.