Role of Blood-Brain Barrier in Alzheimer's Disease

The blood-brain barrier (BBB) is involved in the pathogenesis of Alzheimer's disease (AD). BBB is a highly selective semipermeable structural and chemical barrier which ensures a stable internal environment of the brain and prevents foreign objects invading the brain tissue. BBB dysfunction induces the failure of Aβ transport from brain to the peripheral circulation across the BBB. Especially, decreased levels of LRP-1 (low density lipoprotein receptor-related protein 1) and increased levels of RAGE (receptor for advanced glycation endproducts) at the BBB can cause the failure of Aβ transport. The pathogenesis of AD is related to the BBB structural components, including pericytes, astrocytes, vascular endothelial cells, and tight junctions. BBB dysfunction will trigger neuroinflammation and oxidative stress, then enhance the activity of β-secretase and γ-secretase, and finally promote Aβ generation. A progressive accumulation of Aβ in brain and BBB dysfunction may become a feedback loop that gives rise to cognitive impairment and the onset of dementia. The correlation between BBB dysfunction and tau pathology has been well-reported. Therefore, regulating BBB function may be a new therapeutic target for treating AD.

Diversity of culturable ericoid mycorrhizal fungi of Rhododendron decorum in Yunnan, China

The diversity of ericoid mycorrhizal fungi isolated from Rhododendron decorum Franch. in Yunnan, southwestern China, was examined for the first time. In total 300 hair-root samples were collected from 13 R. decorum individuals in two adjacent wild population sites and one cultivated population site. Two hundred eighteen slow-growing isolates were obtained; the ability of some to form ericoid mycorrhiza was tested in vitro. One hundred twenty-five isolates formed hyphal structures morphologically corresponding to ericoid mycorrhiza, and these were determined by morphological and molecular means to belong to 12 fungal species. There were hardly any differences in species among the three sampled populations. The sequences of several isolates were similar to those of Oidiodendron maius and ericoid mycorrhizal fungi from Helotiales, accounting respectively for 18.4% and 24.8% of the total culturable ericoid mycorrhizal fungi assemblage. Dark septate endophytes were detected in the sampled hair roots by microscopy.

Hydrogen sulfide inhibits mitochondrial fission in neuroblastoma N2a cells through the Drp1/ERK1/2 signaling pathway

Hydrogen sulfide (H2S) has been demonstrated to have various effects on mitochondrial function. The aim of the present study was to investigate the effects of H2S on mitochondrial fission and the potential underlying mechanisms of these effects. Transmission electron microscopy analysis demonstrated that sodium hydrosulfide (NaHS, a donor of H2S) inhibited mitochondrial fission in a dose‑ and time‑dependent manner. Treating neuro‑2a (N2a) mouse neuroblastoma cells with 400 µM NaHS for 16 h significantly increased the % of elongated mitochondria and reduced the number of mitochondria per cell compared with untreated cells. In addition, the viability and ATP generation of N2a cells that were treated with various concentrations of NaHS was examined. The results demonstrated that treatment with 400 and 600 µM NaHS increased cell viability and ATP generation compared with untreated cells. To further understand the effects of H2S on mitochondrial morphology, the protein and mRNA expression levels of dynamin 1 like (Dnm1l, also known as Drp1) were examined, and the results demonstrated that NaHS dose‑dependently reduced Drp1 mRNA and protein levels, consistent with the mitochondrial morphology changes. To determine whether H2S affects mitochondrial morphology through Drp1 expression, Drp1 was overexpressed in N2a cells using a lentivirus encoding the Drp1 cDNA. It was observed that Drp1 overexpression reversed the effects of NaHS. Furthermore, NaHS promoted the phosphorylation of extracellular signal‑regulated kinase (ERK) 1/2, and the effects of NaHS on Drp1 expression were abolished by an ERK1/2 inhibitor (PD98059). The results of the present study indicate that the H2S‑induced decrease in Drp1 mRNA and protein levels and mitochondrial fission may involve the ERK1/2 signaling pathway. The present study suggests that H2S may be used in the future as a potential therapeutic for diseases that may be mediated by abnormal mitochondria fragmentation, such as Alzheimer's disease.

Curcumin Prevents Neuroinflammation by Inducing Microglia to Transform into the M2-phenotype via CaMKKβ-dependent Activation of the AMP-Activated Protein Kinase Signal Pathway

BACKGROUND

Neuroinflammation plays an important role in the pathophysiological process of various neurodegenerative diseases. It is well known that curcumin has obvious anti-inflammatory effects in various neuroinflammation models. However, its effect on the modulation of microglial polarization is largely unknown.

OBJECTIVE

This study aimed to investigate whether curcumin changed microglia to an anti-inflammatory M2-phenotype by activating the AMP-activated protein kinase (AMPK) signaling pathway.

METHODS

LPS treatment was used to establish BV2 cells and primary microglia neuroinflammation models. The neuroinflammation mouse model was established by an intracerebroventricular (ICV) injection of lipopolysaccharide (LPS) in the lateral septal complex region of the brain. TNF-α was measured by ELISA, and cell viability was measured by Cell Counting Kit-8 (CCK-8). The expression of proinflammatory and anti-inflammatory cytokines was examined by Q-PCR and Western blot analysis. Phenotypic polarization of BV2 microglia was detected by immunofluorescence.

RESULTS

Curcumin enhanced AMPK activation in BV2 microglial cells in the presence and absence of LPS. Upon LPS stimulation, the addition of curcumin promoted M2 polarization of BV2 cells, as evidenced by suppressed M1 and the elevated M2 signature protein and gene expression. The effects of curcumin were inhibited by an AMPK inhibitor or AMPK knockdown. Calmodulin-dependent protein kinase kinase β (CaMKKβ) and liver kinase B1 (LKB1) are upstream kinases that activate AMPK. Curcumin can activate AMPK in Hela cells, which do not express LKB1. However, both the CaMKKβ inhibitor and siRNA blocked curcumin activation of AMPK in LPS-stimulated BV2 cells. Moreover, the CaMKKβ inhibitor and siRNA weaken the effect of curcumin suppression on M1 and enhancement of M2 protein and gene expression in LPS-stimulated BV2 cells. Finally, curcumin enhanced AMPK activation in the brain area where microglia were over-activated upon LPS stimulation in an in vivo neuroinflammation model. Moreover, curcumin also suppressed M1 and promoted M2 signature protein and gene expression in this in vivo model.

CONCLUSION

Curcumin enhances microglia M2 polarization via the CaMKKβ-dependent AMPK signaling pathway. Additionally, curcumin treatment was found to be neuroprotective and thus might be considered as a novel therapeutic agent to treat the neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, etc.

Relative contributions of aqueous and dietary uptake of hydrophobic chemicals to the body burden in juvenile rainbow trout

This study assessed the relative contributions of aqueous versus dietary uptake of three hydrophobic chemicals, 1,2, 4-trichlorobenzene (1,2,4-TCB), 1,2,3,4,5-pentachlorobenzene (PeCB), and 2,2',4,4',6,6'-hexachlorobiphenyl (HCBP). Juvenile rainbow trout (Oncorhynchus mykiss) were exposed separately to chemically spiked water and food for 4 days and 12 days, respectively. Chemical concentrations were measured in the food, water, and tissues, and this allowed calculation of uptake rate constants (k(1) from water exposure, k(d) from food exposure). The k(1) values for the three test chemicals were approximately five orders of magnitude greater than the k(d) values. Using these measured uptake rate constants, a simulation model was used to predict the relative aqueous versus dietary uptake when fish were exposed simultaneously to water and food contaminated with these hydrophobic chemicals. The model predicted for all three test chemicals that the two uptake routes would contribute equally to the chemical body burden in fish whenever the food:water chemical concentration ratio was near 10(5). However, using food:water chemical concentration ratios that might be expected in nature, the model predicted that gill uptake could account for over 98% of fish body burden for both 1,2,4-TCB and PeCB uptake (log K(ow) values of 3.98 and 5.03, respectively). For HCBP (log K(ow) of 7.55), the model predicted that the dietary uptake could contribute over 85% of the body burden. Thus, depending on the actual food:water chemical concentration ratio, aqueous uptake via the gills can predominate even when the chemicals have a log K(ow) value greater than 5.0. In addition, we confirmed that dietary uptake of hydrophobic xenobiotics increases with increasing log K(ow).

Quantification of the relative levels of wild-type and lamivudine-resistant mutant virus in serum of HBV-infected patients using microarray

During the course of lamivudine administration in hepatitis B virus (HBV)-infected patients, a dynamic development of the viral population in serum is observed. Total HBV level is initially reduced, then lamivudine-resistant mutants appear, and finally, the viral level is increased. All methods of mutant detection so far described can only identify mutants in the serum, and cannot determine the proportion of those mutants. In this paper, we report the development of a novel technique that can quantify the relative proportion of mutants in serum utilizing gene microarray technology. Based on the nucleotide sequence at the loci of the mutations in lamivudine-resistant HBV mutants, 28 probes were designed and dotted on glass film to prepare the oligonucleotide microarray. Ten standard curves were established by employing 15 reference plasmids as templates. Ten standard math functions were simulated, which allowed quantification of the proportion of mutants in the sample by measuring the value of fluorescent intensity on the microarray. By utilizing the standard math function, the relative proportion of two different mutation sequences in the mixed template could be detected with an error <10%. The HBV-lamivudine oligonucleotide microarray is reliable to quantify the relative proportion of wild-type HBV vs HBV mutants in patient's sera.

Influence of dissolved humic acid on hydrophobic chemical uptake in juvenile rainbow trout

This study measured the chemical uptake of three hydrophobic chemicals (1,2,4-trichlorobenzene (1,2,4-TCB), 1,2,3,4,5-pentachlorobenzene (PeCB) and 2,2',4,4',6,6'-hexachlorobiphenyl (HCBP) with differing octanol-water partition coefficients (log K(ow) values of 3.95, 5.05 and 7.55, respectively) in juvenile rainbow trout (Oncorhynchus mykiss) after 2-day and 4-day aqueous exposures. Because of the affinity of hydrophobic compounds for dissolved organic carbon (DOC) and previous work demonstrating that fish gills take up these three hydrophobic chemicals, we predicted that chemical uptake into the fish would be lowered by the addition of humic acid to the water (1.54, 4.81 and 14.3 mg/l) compared with control fish (no humic acid added to the water). As predicted, humic acid concentrations of >or=4.81 mg/l significantly reduced the whole body concentrations of all three chemicals when compared with 1.54 mg/l humic acid. This effect of humic acid was greatest for HCBP, the chemical with the highest log K(ow), such that chemical uptake was reduced by 3.4-fold for 14.3 mg/l humic acid compared with the control exposure. However, an unexpected finding was that, compared with the control exposure, the lowest concentration of humic acid tested (1.54 mg/l humic acid) significantly increased chemical uptake by up to 112% for the two chemicals with the lower log K(ow), PeCB and 1,2,4-TCB, and did not affect uptake of the high log K(ow) chemical HCBP. We conclude that the ability of DOC to inhibit aqueous uptake of hydrophobic chemicals was dependent on both the concentration of DOC and the log K(ow) of the chemical, but that low humic acid concentrations of approximately 1.5 mg/l can significantly increase uptake of certain chemicals with a log K(ow) between 4 and 5.

CT imaging as a prognostic indicator for patients with pulmonary injury from acute paraquat poisoning

OBJECTIVE

CT imaging may be an effective diagnostic method for assessing the extent and progression of pulmonary injury in patients with acute paraquat (PQ) poisoning.

METHODS

A retrospective review of 78 patients with acute PQ poisoning (survivor group, n=42; non-survivor group, n=36) was conducted to examine the lung segment involvement and CT image characteristics from baseline (first CT scan at a mean of 2.4 days after poisoning) to treatment time (second CT scan 3 days after the first). We examined the association between prognosis and pulmonary lesions indicated by characteristic effusion, fibrosis and consolidation in CT images.

RESULTS

Significant differences were apparent in CT images at baseline and after 3 days between the survivor and the non-survivor groups, with higher levels of pulmonary segment involvement, effusion, consolidation and fibrosis observed in the non-survivor group at baseline (p<0.05). The non-survivor group also showed rapid lesion progression. The receiver operating characteristic curve indicated that the best prognostic value of baseline CT scanning was achieved when performed 2-3 days following the initial exposure.

CONCLUSION

Prognosis correlated with increasing lung segment involvement, extent of disease characteristics visualised using CT and speed of lesion progression from baseline. Prognostic evaluation using CT scanning can be used to effectively provide earlier treatment for patients at risk for severe complications associated with PQ toxicity, such as acidosis; leukocytosis; and renal, hepatic and pancreatic failures.

ADVANCES IN KNOWLEDGE

Chest CT scan can be used 2-3 days following acute PQ poisoning to determine prognosis.

Development of a multiplex PCR assay based on the pilA gene sequences to detect different types of Acidovorax citrulli

Bacterial fruit blotch (BFB) of cucurbits, caused by Acidovorax citrulli, is a major threat to commercial watermelon and melon production worldwide. At present, there are at least two genetically distinct sub-populations (group I and II) of A. citrulli that differ in host preference among cucurbit species and copper sensitivity. In this study, we analyzed the pilA gene sequences of 103 A. citrulli strains from China and other countries. Based on these data, we classified all tested A. citrulli strains into three types. The pilA-based type 1 strains in this study coincided with the previously established group I strains; while the type 2 strains coincided with group II strains. Ten strains that did not cluster with group I or II strains were classified into a new type, designated type 3. Based on differences in pilA sequences, we designed a multiplex PCR assay to distinguish the three A. citrulli pilus types. This multiplex PCR assay has proven to be viable for strain typing of 139 A. citrulli strains and for the detection of this pathogen in artificially inoculated seeds and leaves and naturally infected leaves and fruits. This assay proved to be rapid, accurate, reliable and applicable for early distinction of A. citrulli types associated with BFB epidemics. It may also inform the judicious and environmentally sound use of bactericides, especially copper-based compounds.

Impaired autophagy in amyloid-beta pathology: A traditional review of recent Alzheimer's research

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder. The major pathological changes in AD progression are the generation and accumulation of amyloid-beta (Aβ) peptides as well as the presence of abnormally hyperphosphorylated tau proteins in the brain. Autophagy is a conserved degradation pathway that eliminates abnormal protein aggregates and damaged organelles. Previous studies have suggested that autophagy plays a key role in the production and clearance of Aβ peptides to maintain a steady-state of Aβ peptides levels. However, a growing body of evidence suggests that autophagy is significantly impaired in the pathogenesis of AD, especially in Aβ metabolism. Therefore, this article reviews the latest studies concerning the mechanisms of autophagy, the metabolism of Aβ peptides, and the defective autophagy in the production and clearance of Aβ peptides. Here, we also summarize the established and new strategies for targeting autophagy in vivo and through clinical AD trials to identify gaps in our knowledge and to generate further questions.

Recognition and binding of voltage-dependent anion channel-1 with ATP and NADH by spectroscopic analysis and molecular docking

Recognition and binding of voltage-dependent anion channel-1 with ATP and NADH by spectroscopic analysis and molecular docking.

Anti-Cognitive Decline by Yinxing-Mihuan-Oral-Liquid via Activating CREB/BDNF Signaling and Inhibiting Neuroinflammatory Process

BACKGROUND: Cognitive decline in the normal aging process is one of the most common and prominent problems. Delaying and alleviating cognitive impairment is an important strategy of anti-aging. This study is to aim at investigating the effects of Yinxing-Mihuan-Oral-Liquid(GMOL) on the CREB/BDNF signaling in the normal aging process.METHODS: SD rats were randomly divided into GMOL group and control group. The Morris water maze (MWM) was introduced for behavioral test. Immunohistochemistry and immunofluorescence were used for cAMP response element binding protein 1(CREB1), p-CREB(Ser133), brain-derived neurotrophic factor(BDNF), synaptophysin(SYP) and glial fibrillary acidic protein(GFAP). Western blot was conducted for investigating the levels of CREB1 and p-CREB(Ser133), BDNF, SYP, GFAP and interleukin 6(IL-6). RESULTS:  Our data showed that compared with the control group, GMOL group had higher expression of memory-related proteins, decreased inflammatory factors, and enhanced spatial learning and memory ability.CONCLUSION: The study results show that GMOL ameliorates cognitive impairment of the normal aged SD rats via enhancing the expression of memory biomarkers and inhibiting inflammatory process. The potential neuroprotective role of GMOL in the process of aging may be related to mitigating cognitive decline via activating CREB/BDNF signaling and inhibiting inflammatory process.

[A study of the mechanism of L-NNA on sleep inhibition]

In the present study, the sleep-waking cycle and the immunoreactivity of 5-HT-containing neurons in rats receiving intraperitoneal injections of N-Nitro-L-arginine (L-NNA, 50 mg/kg) and L-arginine (L-arg, 110 mg/kg) were observed respectively. The results showed that injection of L-NNA suppressed both slow wave sleep (SWS) and rapid eye movement sleep (REMS) and increased mean arterial pressure (MAP). L-arg markedly attenuated MAP, whereas SWS and REMS were unchanged. The effects of L-NNA on sleep and MAP were reversed by preinjection of L-arg. In comparison with control group, the positive cells in dorsal raphe nucleus (DR) and raphe magus nucleus (MnR) increased 2 h after injection of L-NNA. The effect was attenuated by preadministration of L-arg. All these results suggest that L-arg: NO pathway is involved in the regulation of sleep-waking cycle and the increment of the positive immunoreactivity of the 5-HT-containing neurons in the DR may be related to the sleep-suppressive effects induced by L-NNA.