Research progress of anti-Alzheimer′s disease drugs targeting Aβ oligomers / 中国药科大学学报

@#Alzheimer''s disease (AD) is the most common cause of senile dementia, accounting for an estimated 60% to 80% of cases, but there are no approved drugs to slow or stop the progressive clinical decline in the past years.Amyloid cascade hypothesis is recognized as the major etiologic basis for AD, however, the failures of several amyloid plaque-targeted programs have led many to dismiss the amyloid beta (Aβ) hypothesis of AD. Several reports show that soluble oligomers of Aβ (AβOs), which appear in brains more than 10 years before the clinical syndrome, are more toxic than Aβ plaque, causing synaptic dysfunction and neuronal apoptosis. Some agents that can effectively inhibit Aβ oligomer formation or block their toxicity made significant efficacy in clinical 2 and 3 trials, with the potential to be approved for the treatment of AD. This article reviews the recent development of AD drugs targeting Aβ oligomers, analyzes their structural characteristics, mechanism of action, preclinical and clinical data, and discusses the future direction of AD treatment, thus providing new strategies for AD drug research.

Prediction of fibril formation by early-stage amyloid peptide aggregation / 药物分析学报

Amyloid fibrils are found in systemic amyloidosis diseases such as Alzheimer's disease, Parkinson's disease, and type II diabetes. Currently, these diseases are diagnosed by observation of fibrils or plaques, which is an ineffective method for early diagnosis and treatment of disease. The goal of this study was to develop a simple and quick method to predict the possibility and speed of fibril formation before its occurrence. Oligomers generated from seven representative peptide segments were first isolated and detected by ion-mobility mass spectrometry (IM-MS). Then, their assemblies were disrupted using formic acid (FA). Interestingly, oligomers that showed small ion intensity changes upon FA addition had rapid fibril formation. By contrast, oligomers that had large ion intensity changes generated fibrils slowly. Two control peptides (aggregation/no fibrils and no aggregation/no fibrils) did not show changes in their ion intensities, which confirmed the ability of this method to predict amyloid formation. In summary, the developed method correlated MS intensity ratio changes of peptide oligomers on FA addition with their amyloid propensities. This method will be useful for monitoring peptide/protein aggregation behavior and essential for their mechanism studies.

Presence of carbohydrate binding modules in extracellular region of class C G-protein coupled receptors (C GPCR): An in silico investigation on sweet taste receptor

Sweet taste receptor (STR) is a C GPCR family member and a suggested drug target for metabolic disorders such asdiabetes. Detailed characteristics of the molecule as well as its ligand interactions mode are yet considerably unclear due toexperimental study limitations of transmembrane proteins. An in silico study was designed to find the putative carbohydratebinding sites on STR. To this end, a-D-glucose and its a-1,4-oligomers (degree of polymerization up to 14) were chosen asprobes and docked into an ensemble of different conformations of the extracellular region of STR monomers (T1R2 andT1R3), using AutoDock Vina. Ensembles had been sampled from an MD simulation experiment. Best poses were furtherenergy-minimized in the presence of water molecules with Amber14 forcefield. For each monomer, four distinct bindingregions consisting of one or two binding pockets could be distinguished. These regions were further investigated withregard to hydrophobicity and hydrophilicity of the residues, as well as residue compositions and non-covalent interactionswith ligands. Popular binding regions showed similar characteristics to carbohydrate binding modules (CBM). Observationof several conserved or semi-conserved residues in these binding regions suggests a possibility to extrapolate the results toother C GPCR family members. In conclusion, presence of CBM in STR and, by extrapolation, in other C GPCR familymembers is suggested, similar to previously proposed sites in gut fungal C GPCRs, through transcriptome analyses. STRmodes of interaction with carbohydrates are also discussed and characteristics of non-covalent interactions in C GPCRfamily are highlighted.

Clinical features and gene mutation analysis of COMP in eight patients with pseudoachondroplasia / 中华内分泌代谢杂志

The clinical features and the mutation of cartilage oligomer matrix protein (COMP) gene were analyzed in 8 patients with pseudoachondroplasia (PSACH).The clinical data and the peripheral blood from 5 male and 3 female probands,their pedigree members,and 250 unrelated volunteers were collected.Eight patients who were sporadic cases,had been detected mutation of COMP gene by DNA sequencing.PSACH is a skeletal disorder characterized by short stature,joint laxity,and early-onset osteoarthritis.The heights of 8 patients were significantly lower than the average level by 3 standard deviations,with short limbs and deformities of legs.Radiographs showed flattening of vertebrae with anterior beaking or tonguing in children and osteoarthritis in adults.As to the patients with short limb dwarfism,short toes,and abnormal radiography findings,PSACH should be suspected and could be confirmed by detection of COMP gene mutation.

Study on the toxic effects of Aβ1-42 oligomers in SHSY5Y with human A53T mutant α-synuclein over-expression / 中国神经精神疾病杂志

Objective To establish an in vitro cell model of Parkinson disease with SHSY5Y cells over-expressing human A53T mutant alpha-synuclein and to examine the effects of Aβ1-42 oligomer on cell survival and autophagy function in the cell model Method The recombinant lentivirus containing the A53T mutant alpha-synuclein gene or empty vector were transfected to SHSY5Y cells. The expression of α-synuclein mRNA in SHSY5Y cells was detected by RT-qPCR. The effect of Aβ1-42 oligomer on cell proliferation was detected with CCK-8 after incubation with Aβ1-42 oligomer for 24 hours. The autophagy-related proteins were evaluated with Western Blot. Result The mRNA and protein levels of alpha-synuclein were significantly increased in SHSY5Y cells expressing alpha-synuclein. There were no significant difference in the cell proliferation between alpha-synuclein group and control group (P<0.001) . Incubation with Aβ1-42 oligomer significantly decreased the proliferation rate in alpha-synuclein group in a dose-dependent manner compared with the control group. The levels of autophagy related proteins including LC3-Ⅱ and Beclin-1 were significantly lower in alpha-synuclein group than in control group (P<0.05). Conclusion This work has constructed an in vitro cell model of Parkinson′s disease. The over-expression of A53T mutant alpha-synuclein do not affect the cell survival whereas the Aβ1-42 oligomer exhibits toxic effects on cells expressing alpha-synuclein possible through suppression of the autophagy activation.

Application of the animal model of intracerebral injection of amyloid-β oligomers to the study of Alzheimer's disease / 药学学报

Progressive accumulation of the amyloid-β peptide (Aβ) in the brain plays a central role in the pathogenesis of Alzheimer's disease (AD). The animal model of intracerebral injection of Aβ oligomers not only provides a method for further exploring the mechanism of Aβ in AD, but also can be used to screen drug candidates targeting Aβ oligomers. This animal model has been widely used in the study of anti-AD drugs and mechanism of AD. In this paper, we summarize the research progress in the animal model of intracerebral injection of soluble Aβ oligomers, including experimental animals, the types of Aβ, the preparation of Aβ oligomers in vitro, injection sites and doses, the duration of modeling, animal behavioral changes, and the pathological mechanisms relating to this animal model, which will contribute to the application of the animal model to various conditions.

Plasma Oligomeric Beta Amyloid in Alzheimer's Disease with History of Agent Orange Exposure

BACKGROUND AND PURPOSE: During the Vietnam War, many Korean soldiers were exposed to Agent Orange. Until now, there existed only limited evidence of association between exposure to Agent Orange and Alzheimer's disease (AD). The main pathological feature of AD is brain amyloidosis. To explore the pathophysiological characteristic of AD with Agent Orange exposure, we compared newly developed amyloid beta (Aβ) oligomer levels in plasma between AD with Agent Orange exposure and without exposure. METHODS: We recruited 48 AD patients with Agent Orange exposure and 66 AD patients without Agent Orange. Using the Multimer Detection System technique, which was based on an enzyme-linked immunosorbent assay, we measured Aβ oligomers in the plasma of study subjects. RESULTS: Compared to normal control patients, plasma Aβ oligomer levels were higher in AD patients regardless of history of Agent Orange exposure. However, AD patients with Agent Orange exposure showed higher plasma Aβ oligomer levels than AD patients without Agent Orange. DISCUSSION: This study showed higher plasma Aβ oligomer levels in AD patients with Agent Orange exposure compared to AD patients without Agent Orange. This finding suggests the possibility of a different pathophysiology of AD patients with Agent Orange exposure from AD patients without Agent Orange.

Calcium mobilizing effect of hawthorn leaf procyanidins in vascular endothelial cells / 中国中药杂志

The hawthorn leaves have the effect of activating blood, removing blood stasis, regulating qi through the veins, dissolving turbidity and lowering lipid. Procyanidinis is one of its main active components and plays an important role in regulating vasoactivity. Previous studies showed that the regulating effect of procyanidins was related to its regulation on nitric oxide secretion from vascular endothelial cells, and this effect was dependent on the extracellular calcium concentration, suggesting that the changes in intracellular calcium ion concentration in endothelial cells may play a key role in this process. However, the research on this issue is still insufficient so far. This study is aimed to observe the effect of hawthorn leaf oligomeric procyanidins (HLP) on calcium mobilization of vascular endothelial cells, and investigate the underlying mechanism. Human umbilical vein endothelial cells (HUVEC) were cultured and labeled with Fura-2. HUVEC were treated with HLP at concentrations of 6.25, 12.5, 25 and 50 mg·L⁻¹, and the intracellular calcium concentrations were measured with a living cell microscope for 30 min. HLP increased the intracellular calcium concentration of HUVEC in a concentration dependent manner; and the intracellular calcium concentrations in 25 and 50 mg·L⁻¹ HLP groups were significantly higher than that in the normal group. With the use of calcium-free incubation buffer, addition of calcium chelating agent EGTA in incubation buffer, or use of inhibitors for sodium calcium exchanger, the effect of HLP was significantly inhibited. On the other hand, the effect of HLP could also be weakened by inhibiting the calcium release from the intracellular storage. In conclusion, these results suggest that HLP can elicit calcium mobilization in vascular endothelial cells, which may be one of the mechanisms for its vascular modulatory activity; and this calcium mobilizing effect may be achieved through promoting both extracellular calcium influx and intracellular calcium release, additionally the former may be related to activating the reverse transport of Na⁺-Ca²⁺ exchangers on the cell membrane.

Level of Alpha-Synuclein Oligomers in Speripheral Blood Plasma and Red Blood Cells in Parkinson's Disease / 中国康复理论与实践

Objective To investigate the level of alpha-synuclein (α-syn) oligomers in peripheral blood plasma and red blood cells (RBC) in patients with Parkinson's disease (PD), and the value of it for diagnosis and evaluation of PD. Methods From March, 2013 to De-cember, 2014, peripheral blood samples were collected from 30 PD patients and 30 healthy coutrols, and the level ofα-syn oligomers in plas-ma and RBC was detected with enzyme linked immunosorbent assay. Results The level of α-syn oligomers was less in both plasma and RBC in the controls than in the patients (t>2.346, P2.242, P0.05). Con-clusion The level ofα-syn oligomers in peripheral RBC and plasma may be helpful for diagnosis of PD, but less for the evaluation of the ill-ness.

Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach

ABSTRACT Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π - bridge, donor group and LUMO are localized on π - bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π - bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π-bridge display an enhanced optoelectronic properties than with less π - bridge.

Parkinson's Disease with Fatigue: Clinical Characteristics and Potential Mechanisms Relevant to α-Synuclein Oligomer

BACKGROUND AND PURPOSE: The aim of this study was to identify the clinical characteristics and potential mechanisms relevant to pathological proteins in Parkinson's disease (PD) patients who experience fatigue. METHODS: PD patients (n=102) were evaluated using a fatigue severity scale and scales for motor and nonmotor symptoms. The levels of three pathological proteins-α-synuclein oligomer, β-amyloid (Aβ)(1-42), and tau-were measured in 102 cerebrospinal fluid (CSF) samples from these PD patients. Linear regression analyses were performed between fatigue score and the CSF levels of the above-listed pathological proteins in PD patients. RESULTS: The frequency of fatigue in the PD patients was 62.75%. The fatigue group had worse motor symptoms and anxiety, depression, and autonomic dysfunction. The CSF level of α-synuclein oligomer was higher and that of Aβ1-42 was lower in the fatigue group than in the non-fatigue group. In multiple linear regression analyses, fatigue severity was significantly and positively correlated with the α-synuclein oligomer level in the CSF of PD patients, after adjusting for confounders. CONCLUSIONS: PD patients experience a high frequency of fatigue. PD patients with fatigue have worse motor and part nonmotor symptoms. Fatigue in PD patients is associated with an increased α-synuclein oligomer level in the CSF.

Transdermal Penetration Enhancement of Arginine Oligomer-chitosan on Tinidazole in vitro and in vivo / 中国药师

Objective:To study the in vitro and in vivo transdermal enhancement of one kind of arginine oligomer-chitosan ( CS-R9). Methods: In vitro mouse skin as the barrier, Franz diffusion cells were used to study the transdermal property of tinidazole ( TNZ) solution in vitro enhanced by CS-R9 using TNZ solution as the negative control and TNZ solution with Azone as the positive control. The rats were randomly divided into three groups, TNZ solution group ( the negative group) , TNZ solution with Azone group (the positive group) and TNZ solution with CS-R9 group. At the predetermined time intervals, 0. 5 ml blood was withdrawn from the rats and TNZ concentration was detected by HPLC to evaluate the enhancement of CS-R9 on TNZ in vivo. Results:Compared with the negative group, CS-R9 had significant enhancement on TNZ trandermal penetration in vitro(P 0. 05). The in vivo results showed CS-R9 exhibited similar transdermal enhancement on TNZ as Azone at the same concentration (P>0. 05), and CS-R9 had sustalned-release property. Conclusion: CS-R9 has promising transdermal en-hancement on TNZ, which is valuable to be studied further.

Spinosin, a C-Glucosylflavone, from Zizyphus jujuba var. spinosa Ameliorates Abeta1-42 Oligomer-Induced Memory Impairment in Mice

Alzheimer's disease (AD) is a neurodegenerative disorder associated with progressive memory loss and neuronal cell death. Although numerous previous studies have been focused on disease progression or reverse pathological symptoms, therapeutic strategies for AD are limited. Alternatively, the identification of traditional herbal medicines or their active compounds has received much attention. The aims of the present study were to characterize the ameliorating effects of spinosin, a C-glucosylflavone isolated from Zizyphus jujuba var. spinosa, on memory impairment or the pathological changes induced through amyloid-beta1-42 oligomer (AbetaO) in mice. Memory impairment was induced by intracerebroventricular injection of AbetaO (50 muM) and spinosin (5, 10, and 20 mg/kg) was administered for 7 days. In the behavioral tasks, the subchronic administration of spinosin (20 mg/kg, p.o.) significantly ameliorated AbetaO-induced cognitive impairment in the passive avoidance task or the Y-maze task. To identify the effects of spinosin on the pathological changes induced through AbetaO, immunohistochemistry and Western blot analyses were performed. Spinosin treatment also reduced the number of activated microglia and astrocytes observed after AbetaO injection. In addition, spinosin rescued the AbetaO-induced decrease in choline acetyltransferase expression levels. These results suggest that spinosin ameliorated memory impairment induced through AbetaO, and these effects were regulated, in part, through neuroprotective activity via the anti-inflammatory effects of spinosin. Therefore, spinosin might be a useful agent against the amyloid b protein-induced cognitive dysfunction observed in AD patients.

Análisis funcional de oligómeros de alfa-sinucleína en la permeabilidad de membranas / Functional analysis of oligomeric alpha-synuclein in membrane permeabilization / Análise funcional dos oligômeros de alfa-sinucleína na permeabilidade das membranas

La enfermedad de Parkinson es un desorden neurodegenerativo común originado por la muerte celular dentro de la substancia nigra pars compacta. Se caracteriza por la presencia de agregados intracelulares proteicos compuestos principalmente por la alfa-sinucleína. Aunque los mecanismos moleculares por los cuales esta proteína contribuye a la toxicidad neuronal todavía se desconocen, se ha sugerido que los intermediarios oligoméricos son citotóxicos y permeabilizan las membranas celulares posiblemente a través de complejos que forman un poro en la bicapa; sin embargo, este mecanismo es altamente controversial. Así pues es necesario identificar el mecanismo por el cual ocurre la permeabilización de membranas para entender la interacción entre oligómeros y lípidos y poder estimar la relevancia biológica de este proceso.En este trabajo se evaluó por espectroscopía de fluorescencia la liberación de contenidos acuosos originados por oligómeros de alfa-sinucleína desde vesículas fosfolipídicas de distinta composición mediante el método ANTS/DPX. Los resultados muestran que la disrupción de membranas solo ocurre en presencia de lípidos aniónicos y también por parámetros de empaquetamiento lipídico, lo que sugiere que la accesibilidad a la región hidrofóbica de las vesículas modula la interacción lípido-oligómero.

Parkinson's disease is a common neurodegenerative disorder marked by increased cell death within the substantia nigra pars compacta. It is characterized by the presence of intracellular aggregates composed primarily of the protein alpha-synuclein. How the aggregation of a-synuclein is related to neuronal degeneration is an important unresolved question. Oligomeric intermediates have been found to be more toxic to cells than monomeric or fibrillar forms of the protein. A possible mechanism by which oligomers could be toxic is through the disruption and permeabilization of cellular membranes. The proposed disruption mechanism is the formation of pore-like structures within the lipid bilayer although this mechanism is still highly controversial. To identify the mechanism through which membrane permeabilization is facilitated and to estimate the biological relevance of this process, it is crucial to have a greater knowledge of the lipid-oligomer interaction. The membrane disruptive effect of Alpha-synuclein oligomers on lipid vesicles of different headgroup composition using the ANTS/DPX assay was evaluated in this work. It was shown that membrane permeabilization is mainly determined by the presence of negatively charged lipids and also by lipid packing parameters, suggesting that the accessibility to the bilayer hydrocarbon core modulates oligomer-membrane interaction.

pars compacta. é caracterizada pela presença de agregados intracelulares protéicos compostos especialmente pela alfa-sinucleína.Mesmo que se desconheça os mecanismos moleculares por onde essa proteína contribui para toxicidade neuronal, existe uma possibilidade de que os intermediários oligoméricos sejam citotóxicos, e permeabilizam as membranas celulares possivelmente através de complexos que formam um poro na capa dupla, entretanto, este mecanismo gera muita controvérsia. Sendo assim, é necessário identificar o mecanismo responsável pela permeabilidade das membranas para entender a interação entre os oligômeros e os lipídios, e para ter uma estimativa da relevância biológica deste processo. Neste trabalho, analisamos através de espectroscopia de fluorescência, a liberação dos conteúdos aquoso originados por oligômeros de alfa-sinucleína a partir das vesículas fosfolídicas de composição diferente através do método ANTS/DPX. Os resultados mostraram que a ruptura de membranas ocorrerá somente diante da presença de lipídios aniônicos, e também pelos parâmetros de empacotamento lipídico, e isso sugere que a acessibilidade à região hidrofóbica das vesículas faz a modulação da interação lípidio-oligômero.

Galactosylated alginate and sodium alginate：What is the optimal mass ratio for maintaining the mechanical stability? / 中国组织工程研究

10.3969/j.issn.2095-4344.2013.25.012

Biodistribution of 99mTc Tricarbonyl Glycine Oligomers

99mTc tricarbonyl glycine monomers, trimers, and pentamers were synthesized and evaluated for their radiolabeling and in vivo distribution characteristics. We synthesized a 99mTc-tricarbonyl precursor with a low oxidation state (I). 99mTc(CO)3(H2O)3 + was then made to react with monomeric and oligomeric glycine for the development of bifunctional chelating sequences for biomolecules. Labeling yields of 99mTc-tricarbonyl glycine monomers and oligomers were checked by high-performance liquid chromatography. The labeling yields of 99mTc-tricarbonyl glycine and glycine oligomers were more than 95%. We evaluated the characteristics of 99mTc-tricarbonyl glycine oligomers by carrying out a lipophilicity test and an imaging study. The octanol-water partition coefficient of 99mTc tricarbonyl glycine oligomers indicated hydrophilic properties. Single-photon emission computed tomography imaging of 99mTc-tricarbonyl glycine oligomers showed rapid renal excretion through the kidneys with a low uptake in the liver, especially of 99mTc tricarbonyl triglycine. Furthermore, we verified that the addition of triglycine to prototype biomolecules (AGRGDS and RRPYIL) results in the improvement of radiolabeling yield. From these results, we conclude that triglycine has good characteristics for use as a bifunctional chelating sequence for a 99mTc-tricarbonyl-based biomolecular imaging probe.

Application of Pseudoreplica Technique in Electron Microscope Observation of A? / 医学研究杂志

Objective To investigate the effects of application of pseudoreplica technique in electron microscope observation of A?.Methods With the modification of classical pseudoreplica technique,ADDLs were spotted and concentrated on the gel before negative staining.Results The structures of 5nm to10nm spherical granules and 20 to 30nm coils were visualized by transmission electron microscopy(TEM).Conclusion Pseudoreplica is rapid and effective in ADDLs condensation,negative staining especially in further ultra miero structure observation and research.

Preventive Effects of Chitosan on the Disorders of Hepatic Functions and Lipid Metabolism in Rats Treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

This study was conducted to fine out the preventive effects of chitosan and chitosan oligomer on the disorders of hepatic functions and lipid metabolism induced by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), using adult male rats (SD) for four weeks. Rats were fed chitosan (4%) or chitosan oligomer (4%) diets respectively before 3weeks of TCDD treatment (50 ug/kg BW) by intraperitoneal injection and then continually supplied these diets for one week until being sacrificed. The elevation of serum total and LDL cholesterol levels induced by TCDD treatment was significantly reduced in the rats fed chitosan diets. The increment of liver triglyceride levels caused by TCDD treatment was tended to suppress in all rats fed chitosan and chitosan oligomer diets. Fecal total lipid and cholesterol excretion were high levels in the rats fed chitosan diets. The hepatic cytosolic catalase activities significantly decreased by TCDD treatment appeared recovering trend by chitosan diets. In hepatic microsomal cytochrome p-450, NADPH cytochrome p-450 reductase, ethoxycoumarin-o-deethylase (ECOD) and benzphetamin N-demethylase (BPND), chitosan than chitosan oligomer diets apparently decreased the increasing levels by TCDD treatment. In histochemical observation, the fat droplets and apoptosis of hepatocytes by TCDD treatment were markedly alleviated by chitosan and chitosan oligomer diets. These results indicate that chitosan, more than chitosan oligomer can exert preventive effects on some disorders of hepatic functions and lipids accumulation by TCDD.