Regional Amyloid Deposition in Amnestic Mild Cognitive Impairment and Alzheimer's Disease Evaluated by [18F]AV-45 Positron Emission Tomography in Chinese Population

Background

To compare the neocortical amyloid loads among cognitively normal (CN), amnestic mild cognitive impairment (aMCI), and Alzheimer''s disease (AD) subjects with [¹⁸F]AV-45 positron emission tomography (PET).

Materials and Methods

[¹⁸F]AV-45 PET was performed in 11 CN, 13 aMCI, and 12 AD subjects to compare the cerebral cortex-to-whole cerebellum standard uptake value ratios (SUVRs) of global and individual volumes of interest (VOIs) cerebral cortex. The correlation between global cortical [¹⁸F]AV-45 SUVRs and Mini-Mental State Examination (MMSE) scores was analyzed.

Results

The global cortical [¹⁸F]AV-45 SUVRs were significantly different among the CN (1.08±0.08), aMCI (1.27±0.06), and AD groups (1.34±0.13) (p = 0.0003) with amyloidosis positivity rates of 9%, 62%, and 92% in the three groups respectively. Compared to CN subjects, AD subjects had higher SUVRs in the global cortical, precuneus, frontal, parietal, occipital, temporal, and posterior cingulate areas; while aMCI subjects had higher values in the global cortical, precuneus, frontal, occipital and posterior cingulate areas. There were negative correlations of MMSE scores with SUVRs in the global cortical, precuneus, frontal, parietal, occipital, temporal, posterior cingulate and anterior cingulate areas on a combined subject pool of the three groups after age and education attainment adjustment.

Conclusions

Amyloid deposition occurs relatively early in precuneus, frontal and posterior cingulate in aMCI subjects. Higher [¹⁸F]AV-45 accumulation is present in parietal, occipital and temporal gyri in AD subjects compared to the aMCI group. Significant correlation between MMSE scores and [¹⁸F]AV-45 SUVRs can be observed among CN, aMCI and AD subjects.     

A Comparison of Positron Emission Tomography and Colonoscopy for the Detection of Advanced Colorectal Neoplasms in Subjects Undergoing a Health Check-Up

Background & Aims

There is no agreement as to whether F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) screening for advanced colorectal neoplasms is meaningful. This retrospective study was undertaken to determine whether FDG PET/CT may be a valuable screening tool for the detection of advanced colorectal neoplasms.

Methods

A retrospective review of the records of 1,109 FDG PET/CT scans acquired from January 2007 to December 2011 was performed. Colonoscopy and FDG PET/CT imaging were performed within two days of each other. The results of colonoscopy were taken as the gold standard, either with or without the results of the histopathological examination. An advanced neoplasm was defined as the presence of a malignant tumor, an adenoma ≥1 cm, or histological evidence of high-grade dysplasia or significant villous components.

Results

A total of 36 subjects had advanced colorectal neoplasms detected by colonoscopy (totaling 38 neoplasms). Six of the 38 neoplasms were also detected by FDG PET/CT. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of FDG PET/CT in the detection of advanced colorectal neoplasms were 15.8% (6/38), 99.1% (1063/1073), 37.5% (6/16), 97.1% (1063/1095), and 96.2% (1069/1111) respectively. The presence of lesions with an endoscopic size ≤1.5 cm (P<0.001) and low-grade dysplasia (P<0.001) were the main predictors of false-negative FDG PET/CT findings.

Conclusions

We conclude that FDG PET/CT screening of advanced colorectal neoplasms is unwarranted, especially in the presence of lesions with an endoscopic size ≤1.5 cm or low-grade dysplasia.     

Population dynamics of Meloidogyne incognita on black pepper plants in two agro-ecological regions in Vietnam

The objective of our study was to examine the effect of local environmental conditions, especially air temperature and rainfall, in two agro-ecological regions in Vietnam on the population dynamics of Meloidogyne incognita on black pepper plants and on percentage root galling. The two study sites were situated in Cam Lo, Quang Tri province (North Central Coast) and Buon Ma Thuot, Dac Lac province (Central Highlands). At the study sites, 13 plant-parasitic nematode taxa belonging to 12 genera were identified. Ten of these taxa were present in both study sites. Helicotylenchus certus, Hemicriconemoides cocophilus and Pratylenchus coffeae were only found in Buon Ma Thuot. Based on nematode population densities, M. incognita was the most abundant taxon present. Rainfall and air temperature differed significantly between the two study sites. The most important climatic difference was rainfall: in Buon Ma Thuot, the rainy season lasted 2 months longer and the monthly rainfall during the rainy season was much higher compared to Cam Lo. Although this difference resulted in some differences in the population dynamics of M. incognita in the soil and roots of the black pepper variety Vinh Linh, the highest root population densities were observed in both study sites during the first half of the dry season. In Cam Lo, the highest percentage root galling was observed during the first half of the dry season. In Buon Ma Thuot, the highest percentage root galling was observed towards the end of the rainy season. Estimating the population densities if M. incognita to decide on the application of a management strategy should be done during the first half of the dry season.     

Diethylmaleate and iodoacetate in combination caused profound cell death in astrocytes

Energy failure and oxidative stress have been implicated in the pathogenesis of ischemia. Here, we report a potential link between cytosolic phospholipase A₂ (cPLA₂) activation and energy failure/oxidative stress‐induced astrocyte damage involving reactive oxygen species (ROS), protein kinase C‐α (PKC‐α), Src, Raf, and extracellular signal‐regulated kinase (ERK) signaling and concurrent elevation of endogenous chelatable zinc. Energy failure and oxidative stress were produced by treating astrocytes with glycolytic inhibitor iodoacetate and glutathione chelator diethylmaleate, respectively. Diethylmaleate and iodoacetate in combination caused augmented damage to astrocytes in a time‐ and concentration‐dependent manner. The cell death caused by diethylmaleate/iodoacetate was accompanied by increased ROS generation, PKC‐α membrane translocation, Src, Raf, ERK, and cPLA₂ phosphorylation. Pharmacological studies revealed that these activations all contributed to diethylmaleate/iodoacetate‐induced astrocyte death. Intriguingly, the mobilization of endogenous chelatable zinc was observed in diethylmaleate/iodoacetate‐treated astrocytes. Zinc appears to act as a downstream mediator in response to diethylmaleate/iodoacetate treatment because of the attenuating effects of its chelator N,N,N′,N′‐tetrakis(2‐pyridylmethyl)ethylenediamine. These observations indicate that ROS/PKC‐α, Src/Raf/ERK signaling and cPLA₂ are active participants in diethylmaleate/iodoacetate‐induced astrocyte death and contribute to a vicious cycle between the depletion of ATP/glutathione and the mobilization of chelatable zinc as critical upstream effectors in initiating cytotoxic cascades.

     

Functional Investigation of Transmembrane Helix 3 in H+-Translocating Pyrophosphatase

H⁺-translocating pyrophosphatase (H⁺-PPase, EC 3.6.1.1) plays an important role in acidifying vacuoles by transporting protons across membranes at the expense of pyrophosphate (PP_i) hydrolysis. Vigna radiata H⁺-PPase (VrH⁺-PPase) contains 16 transmembrane helices (TMs). The hydrophobicity of TM3 is relatively lower than that of most other TMs, and the amino acids in this TM are highly conserved in plants. Furthermore, TM5 and -6, which are the core TMs involving in H⁺-PPase functions, are near TM3. It is thus proposed that TM3 is associated with H⁺-PPase activity. To address this possibility, site-directed mutagenesis was applied in this investigation to determine the role of TM3 in VrH⁺-PPase. Upon alanine/serine substitution, T138 and S142, whose side chains face toward the center TMs, were found to be involved in efficient proton transport. G149/S153 and G160/A164 pairs at the crucial termini of the two GxxxG-like motifs are indispensable in maintaining enzymatic activities and conformational stability. Moreover, stability in the vicinity surrounding G149 is pivotal for efficient expression. S153, M161 and A164 are critical for the K⁺-mediated stimulation of H⁺-PPase. Taken together, our results demonstrate that TM3 plays essential roles in PP_i hydrolysis, proton transport, expression, and K⁺ stimulation of H⁺-PPase.     

A DNA vaccine against cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) prevents tumor growth

Co-stimulatory signaling pathway triggered by the binding of B7.1/B7.2 (CD80/86) of antigen-presenting cells (APCs) to CD28 of T cells is required for optimal T-cell activation. Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is a negative regulator of T cell activation, which competes with CD28 for B7.1/B7.2 binding with a greater affinity. Ipilimumab, a monoclonal antibody against CTLA-4, has shown positive efficacy in a pivotal clinical trial for the treatment of metastatic melanoma and was approved by FDA. However, the cost of monoclonal antibody-based therapeutics might limit the number of patients treated. To develop a novel therapeutics specifically targeting CTLA-4, we constructed a DNA vaccine by cloning the sequence of CTLA-4 fused with a transmembrane domain sequence of placental alkaline phosphatase (PLAP) into a mammalian expression plasmid, pVAC-1. Immunization with the resulting construct, pVAC-1-hCTLA-4, elicited antibody specific to human CTLA-4 with cross reactivity to murine CTLA-4, which was sufficient for inhibiting B16F10 tumor growth in c57BL/6 mice in the absence of measurable toxicity. Coupling liposome with pVAC-1-mCTLA-4 could break tolerance to self-antigen in BALB/c mice and induce potent immunity against murine CTLA-4, and suppress growth of subcutaneous renal cell carcinoma (Renca).     

Discovery of 3-phenyl-1H-5-pyrazolylamine derivatives containing a urea pharmacophore as potent and efficacious inhibitors of FMS-like tyrosine kinase-3 (FLT3)

Preclinical investigations and early clinical trials suggest that FLT3 inhibitors are a viable therapy for acute myeloid leukemia. However, early clinical data have been underwhelming due to incomplete inhibition of FLT3. We have developed 3-phenyl-1H-5-pyrazolylamine as an efficient template for kinase inhibitors. Structure–activity relationships led to the discovery of sulfonamide, carbamate and urea series of FLT3 inhibitors. Previous studies showed that the sulfonamide 4 and carbamate 5 series were potent and selective FLT3 inhibitors with good in vivo efficacy. Herein, we describe the urea series, which we found to be potent inhibitors of FLT3 and VEGFR2. Some inhibited growth of FLT3-mutated MOLM-13 cells more strongly than the FLT3 inhibitors sorafenib (2) and ABT-869 (3). In preliminary in vivo toxicity studies of the four most active compounds, 10f was found to be the least toxic. A further in vivo efficacy study demonstrated that 10f achieved complete tumor regression in a higher proportion of MOLM-13 xenograft mice than 4 and 5 (70% vs 10% and 40%). These results show that compound 10f possesses improved pharmacologic and selectivity profiles and could be more effective than previously disclosed FLT3 inhibitors in the treatment of acute myeloid leukemia.     

Identification and characterization of autotransporter proteins of Yersinia pestis KIM

Yersinia pestis is a Gram-negative bacterium that causes plague. Currently, plague is considered a re-emerging infectious disease and Y. pestis a potential bioterrorism agent. Autotransporters (ATs) are virulence proteins translocated by a variety of pathogenic Gram-negative bacteria across the cell envelope to the cell surface or extracellular environment. In this study, we screened the genome of Yersinia pestis KIM for AT genes whose expression might be relevant for the pathogenicity of this plague-causing organism. By in silico analyses, we identified ten putative AT genes in the genomic sequence of Y. pestis KIM; two of these genes are located within known pathogenicity islands. The expression of all ten putative AT genes in Y. pestis KIM was confirmed by RT-PCR. Five genes, designated yapA, yapC, yapG, yapK and yapN, were subsequently cloned and expressed in Escherichia coli K12 for protein secretion studies. Two forms of the YapA protein (130 kDa and 115 kDa) were found secreted into the culture medium. Protease cleavage at the C terminus of YapA released the protein from the cell surface. Outer membrane localization of YapC (65 kDa), YapG (100 kDa), YapK (130 kDa), and YapN (60 kDa) was established by cell fractionation, and cell surface localization of YapC and YapN was demonstrated by protease accessibility experiments. In functional studies, YapN and YapK showed hemagglutination activity and YapC exhibited autoagglutination activity. Data reported here represent the first study on Y. pestis ATs.     

Synthesis and anti-Trypanosoma cruzi activity of naphthoquinone-containing triazoles: Electrochemical studies on the effects of the quinoidal moiety

In our continued search for novel trypanocidal compounds, twenty-six derivatives of para- and ortho-naphthoquinones coupled to 1,2,3-triazoles were synthesized. These compounds were evaluated against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. Compounds 17–24, 28–30 and 36–38 are described herein for the first time. Three of these novel compounds (28–30) were found to be more potent than the standard drug benznidazole, with IC₅₀/24 h values between 6.8 and 80.8 μM. Analysis of the toxicity to heart muscle cells led to LC₅₀/24 h of <125, 63.1 and 281.6 μM for 28, 29 and 30, respectively. Displaying a selectivity index of 34.3, compound 30 will be further evaluated in vivo. The electrochemical properties of selected compounds were evaluated in an attempt to find correlations with trypanocidal activity, and it was observed that more electrophilic quinones were generally more potent.