Implication of altered α7 nicotinic receptors and amyloid deposition in the Alzheimer's brain

Introduction

Brain amyloid-β protein (Aβ) deposition is a key pathology of Alzheimer's disease (AD). Cholinergic degeneration, including reductions in α7 nicotinic acetylcholine receptors (α7-nAChR), is also known as a pathophysiology of AD. Recent imaging studies have shown cognitively normal subjects with Aβ depositions, indicating a missing link between Aβ deposition and cognitive decline.

Objectives

To clarify relationships among the Aβ burden, α7-nAChR availability, and cognitive declines in AD.

Aims

To measure brain Aβ deposition and α7-nAChR availability in the same patients with AD using positron emission tomography (PET).

Methods

Twenty AD patients and age-matched 20 healthy adults were studied. The α7-nAChR availability and Aβ deposition were evaluated using PET with [11C]MeQAA and [11C]PIB, respectively. Levels of specific binding were estimated by a simplified reference tissue method (BPND) for [11C]MeQAA and a tissue ratio method (SUVR) for using [11C]PIB. The values were compared with clinical measures of various cognitive functions using regions of interest (ROIs)-based and statistical parametric mapping (SPM) analyses.

Results

[11C]MeQAA BPND levels were extensively lower in the cholinergic projection regions of AD. There was a significant negative correlation between [11C]PIB SUVR and [11C]MeQAA BPND in the nucleus basalis of Mynert (NBM). The NBM [11C]PIB SUVR was negatively correlated with the [11C]MeQAA BPND level in the anterior and posterior cingulate cortices, whereas the relation within the same region showed weak correlation. Also we found significant correlation between cognitive decline and [11C]MeQAA BPND levels in the NBM.

Conclusions

Aβ deposition-linked α7-nAChR dysfunction may account for cognitive decline in AD.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Association between serum uric acid and lumbar spine bone mineral density in peri- and postmenopausal Japanese women

SUMMARY

Previous studies on the association between uric acid and bone mineral density yielded conflicting results. In this study, we demonstrated positive association between uric acid and lumbar spine bone mineral density in peri- and postmenopausal Japanese women. Further research is needed to elucidate the underlying mechanism.

INTRODUCTION

Oxidative stress has been implicated in the pathogenesis of osteoporosis. Uric acid, a potent antioxidant substance, has been associated with bone mineral density but previous studies have yielded conflicting results. The objective of the study was to examine the association between serum uric acid and lumbar spine bone mineral density (BMD).

METHODS

This was a retrospective analysis of medical records of 615 women, aged 45-75 years, who had lumbar spine BMD measurement by dual-energy X-ray absorptiometry as a part of health checkup from August 2011 to July 2012.

RESULTS

Mean serum uric acid level was 4.7 mg/dL. Serum uric acid level was positively and significantly associated with lumbar spine BMD independent of age, body mass index, smoking, drinking, physical activity, years after menopause, diabetes mellitus, hypertension, serum calcium, estimated glomerular filtration rate, plasma C-reactive protein, and serum alkaline phosphatase (standardized beta = 0.078, p = 0.049). Uric acid rapidly increased until the age of 60 years, and then decelerated but continued to increase thereafter. The association between lumbar spine BMD and uric acid remained significantly positive after excluding women older than 60 years.

CONCLUSION

The present study showed that higher uric acid levels were linearly associated with higher lumbar spine BMD in peri- and postmenopausal Japanese women. Further research is needed to elucidate the underlying mechanism of the association between uric acid and BMD.

miR-148a is an androgen-responsive microRNA that promotes LNCaP prostate cell growth by repressing its target CAND1 expression

Recent advances in cancer biology reveal that microRNAs (miRNAs) are involved in the regulation of cancer-related genes, or they function as tumor suppressors or oncogenes. In prostate cancer, evidence has accumulated for the contribution of the androgen-dependent gene network to tumor growth, although the precise functions of miRNAs in prostate cancer remain to be investigated. Here, we identified androgen-responsive miRNAs by the short RNA sequencing analysis in LNCaP prostate cancer cells. Among 10 miRNAs with known sequences, we have determined that miR-148a reduces the expression of cullin-associated and neddylation-dissociated 1 (CAND1), a negative regulator of SKP1-Cullin1-F-box (SCF) ubiquitin ligases, by binding to the 3'-untranslated region of CAND1 mRNA. CAND1 knockdown by small interfering RNA promoted the proliferation of LNCaP cells. Our study indicates the potential contribution of miR-148a to the growth of human prostate cancer.

Characteristics of leachate from pyrolysis residue of sewage sludge

The pyrolysis residue (SP) of sewage sludge (SS) produced at 500 degrees C was subjected to batch and column leaching tests to investigate the release of its organic and inorganic constituents and metals. For comparison, incineration ash (SI) obtained from a SS incinerator was also tested. Pyrolysis and incineration reduced organic matter of SS from 0.78 kg kg(-1)-dry SS to 0.16 and 0.01 kg kg(-1)-dry SS, respectively. Heavy metals remained in SP without being volatilized, although Cd and Pb were transferred into the off-gas during incineration. In the batch leaching test with the leaching liquid-to-solid mass ratio (L/S)=10, the pH of the SS, SP, and SI filtrates was 6.3, 7.9, and 11.0, respectively. The total organic carbon concentrations were in the order SS (877 l mg l(-1))>>SP (99 mg l(-1))>SI (26 mg l(-1)). The SP and SI filtrates met the landfill standard for the Cd and Pb concentrations (<0.3 mg l(-1)). In the column tests, although the SP contained more organic matter than that of SI, its carbon discharge into the leachate under aerobic conditions was similar to that of SI under anaerobic conditions. The leaching of heavy metals, such as Cd, Cr, Pb, and Zn, was also suppressed in SP during the active decomposition of organic matter. We demonstrated that pyrolysis reduces the potential release of pollutants from sewage sludge in landfill, making it a promising method of treating sewage sludge before landfilling.

Identification of novel androgen response genes in prostate cancer cells by coupling chromatin immunoprecipitation and genomic microarray analysis

The androgen receptor (AR) plays a key role as a transcriptional factor in prostate development and carcinogenesis. Identification of androgen-regulated genes is essential to elucidate the AR pathophysiology in prostate cancer. Here, we identified androgen target genes that are directly regulated by AR in LNCaP cells, by combining chromatin immunoprecipitation (ChIP) with tiling microarrays (ChIP-chip). ChIP-enriched or control DNAs from the cells treated with R1881 were hybridized with the ENCODE array, in which a set of regions representing approximately 1% of the whole genome. We chose 10 bona fide AR-binding sites (ARBSs) (P<1e-5) and validated their significant AR recruitment ligand dependently. Eight upregulated genes by R1881 were identified in the vicinity of the ARBSs. Among the upregulated genes, we focused on UGT1A and CDH2 as AR target genes, because the ARBSs close to these genes (in UGT1A distal promoter and CDH2 intron 1) were most significantly associated with acetylated histone H3/H4, RNA polymerase II and p160 family co-activators. Luciferase reporter constructs including those two ARBSs exhibited ligand-dependent transcriptional regulator/enhancer activities. The present study would be powerful to extend our knowledge of the diversity of androgen genetic network and steroid action in prostate cancer cells.

Sirt1 inhibitor, Sirtinol, induces senescence-like growth arrest with attenuated Ras-MAPK signaling in human cancer cells

The induction of senescence-like growth arrest has emerged as a putative contributor to the anticancer effects of chemotherapeutic agents. Clinical trials are underway to evaluate the efficacy of inhibitors for class I and II histone deacetylases to treat malignancies. However, a potential antiproliferative effect of inhibitor for Sirt1, which is an NAD(+)-dependent deacetylase and belongs to class III histone deacetylases, has not yet been explored. Here, we show that Sirt1 inhibitor, Sirtinol, induced senescence-like growth arrest characterized by induction of senescence-associated beta-galactosidase activity and increased expression of plasminogen activator inhibitor 1 in human breast cancer MCF-7 cells and lung cancer H1299 cells. Sirtinol-induced senescence-like growth arrest was accompanied by impaired activation of mitogen-activated protein kinase (MAPK) pathways, namely, extracellular-regulated protein kinase, c-jun N-terminal kinase and p38 MAPK, in response to epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I). Active Ras was reduced in Sirtinol-treated senescent cells compared with untreated cells. However, tyrosine phosphorylation of the receptors for EGF and IGF-I and Akt/PKB activation were unaltered by Sirtinol treatment. These results suggest that inhibitors for Sirt1 may have anticancer potential, and that impaired activation of Ras-MAPK pathway might take part in a senescence-like growth arrest program induced by Sirtinol.

EBAG9/RCAS1 expression in hepatocellular carcinoma: correlation with tumour dedifferentiation and proliferation

The oestrogen-responsive gene, EBAG9, whose product is identical to the cancer cell surface antigen RCAS1, is reported to be associated with tumour progression and invasiveness in various carcinomas. In this study, we examined the expression of EBAG9/RCAS1 in hepatocellular carcinoma (HCC), with special reference to its relationship with the stepwise evolution of HCC. Expression was examined by immunohistochemistry and western blotting analysis in 143 HCCs, as well as in non-cancerous liver tissues. After which, the association between enhanced EBAG9/RCAS1 expression and various clinicopathological parameters including Ki-67 labelling index (LI), a marker of proliferative activity, was evaluated. There was a constant low level of EBAG9/RCAS1 expression in non-cancerous liver tissues, with a regular cytoplasmic distribution. Positive immunoreactivity for EBAG9/RCAS1 was detected on the surface and in the cytoplasm of 84 HCC tumours, with an irregular staining pattern. Enhanced EBAG9/RCAS1 expression was correlated with a lower degree of differentiation and Ki-67 LI. Interestingly, expression was enhanced specifically in the less differentiated lesions within 'nodule-in-nodule' tumours. In conclusion, EBAG9/RCAS1 was associated with HCC tumour dedifferentiation and increased proliferative activity. Its exact functional role remains to be established.

High positive frequency of antibodies to metallothionein and heat shock protein 70 in sera of patients with metal allergy

Two principal types of stress protein, heat shock proteins (hsps) and metallothionein (MT), are induced in cells responding to a variety of stresses. They play an important role in protecting cells from these stresses. However, many reports indicate that antibodies to hsps are present in human serum and are associated with several autoimmunity diseases. Metals, which are commonly allergenic to humans, induce both MT and hsp70 (one of the hsps family). Until now, there has been no report of any antibody to MT in human serum. In the present study, serum samples from healthy controls (Group I), and patients suffering from atopic dermatitis without (Group II) or with (Group III) metal allergy, were measured for antibodies to MT and hsp70, using an enzyme-linked immunosorbent assay (ELISA). Metal allergy was confirmed by patch testing. We first found that antibody to MT exists in human serum. We also found a high positive frequency of antibody to MT (51.3%) and to hsp70 (43.6%) in the sera of Group III, compared to those of Group I (3.8% and 5.1%) or Group II (6.4% and 5.1%). Furthermore, there was a strong positive correlation between antibody to MT and antibody to hsp70 in Group III (P = 0.0013), but not in Group I and Group II. Our results indicate that antibody to MT exists in human serum, as do antibodies to hsps, and suggest that elevated levels of MT and hsp70 antibodies are associated with metal allergy in atopic patients.

Estrogen receptor beta is involved in the anorectic action of estrogen

OBJECTIVE

Estrogen has been implicated in feeding behavior and adiposity. This study was undertaken to elucidate the mechanism underlying the anti-obesity and anorectic action of estrogen and the role of estrogen receptor (ER) in the central nervous system.

METHODS AND RESULTS

Ovariectomy in 8-week-old female Wistar rats induced hyperphagia along with an increase in body weight and abdominal fat accumulation compared to control sham-operated rats. These changes were fully reversed by subcutaneous replacement of estradiol and were abrogated by pair-feeding. Then, the effects of intracerebroventricular infusion of estradiol, alone or in combination with antisense oligodeoxynucleotides (ODN), for ER in ovariectomized rats were examined. The estradiol group showed 10-20% lower daily food intake, and after the 2-week infusion period a 14% reduction in body weight with a similar reduction in abdominal fat compared to the vehicle group. The inhibitory effect of estradiol on food intake and body weight was blocked by co-administration of ER-beta antisense ODN, whereas ER-alpha antisense ODN did not show any influence.

CONCLUSION

These results indicate that ER-beta in the central nervous system is involved in the anorectic action of estrogen.

A comparison of low versus standard dose pravastatin therapy for the prevention of cardiovascular events in the elderly: the pravastatin anti-atherosclerosis trial in the elderly (PATE)

Treatment with low drug doses is generally recommended in the elderly. However, the efficacy of low dose 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor treatment in elderly hypercholesterolemic patients has never been examined. Therefore, we compared the effect of low-dose with standard dose pravastatin, an HMG CoA reductase inhibitor, on the incidence of cardiovascular events (CVEs) in elderly patients with hypercholesterolemia in a randomized prospective trial. Subjects aged > or = 60 years (73 +/- 6 years) with serum total cholesterol (TC) levels of 220-280 mg/dL were randomized to the low-dose (groupL, 5 mg/day; n=334) or standard dose (groupS, 10-20mg/day; n= 331). Baseline TC levels were similar in the 2 groups (253 +/-15 mg/dL). Patients were followed for 3-5 years (mean 3.9 years). TC levels decreased from baseline by 11-13% in group L and by 15-17% in groupS. TC levels at 1 year in S and L group were 209 +/- 2 mg/ dL (16 +/- 1% decrease) and 221+/- 2 mg/dL (12 +/- 1% decrease), respectively. Forty two and 29 CVEs occurred in group L and S, respectively. The incidence of CVEs was significantly lower in group S than in group L (P = 0.046, generalized Wilcoxon test; P = 0.096, log-rank test). The risk ratio for group S compared with group L was 0.674 (95% confidence interval: 0.423-1.074). Subgroup analyses suggested that the difference in the incidence of CVEs between the 2 groups was more clear in subjects without diabetes mellitus, with TC levels of < 253 mg/dL, and with TG levels of > or = 133 mg/dL. The incidence of CVEs in group S was significantly lower than that in group L in subjects without both diabetes mellitus and previous cardiovascular disease (P = 0.026, generalized Wilcoxon test; P = 0.032, log rank test). These findings suggest that standard-dose pravastatin (10-20 mg/day) is more effective in reducing the incidence of CVEs in the elderly than low dose pravastatin (5 mg/ day), especially in nondiabetic elderly patients with mild hypercholesterolemia or previous cardiovascular disease.

Differential expression of secreted frizzled-related protein 4 in decidual cells during pregnancy

During pregnancy, the uterus shows marked morphological and physiological changes under the regulation of ovarian steroid. To elucidate the molecular cues of these changes, we tried to identify the transcripts differentially expressed in the pregnant rat uterus by using the suppression subtractive hybridization method. Seven independent clones were isolated and one of the up-regulated genes was secreted frizzled-related protein 4 (sFRP4). sFRP4 contains a Wnt-binding domain and belongs to the secreted frizzled protein family whose members are assumed to function as modulators of the Wnt signal. The expression level of sFRP4 mRNA reached a peak in the pregnant uterus on day 12, when uterine decidualization was almost complete in the rat. In situ hybridization histochemistry revealed that sFRP4 transcripts were observed in the decidual cells. In addition, proliferating cell nuclear antigen (PCNA)-positive cells were shown to be overlapped in decidua, suggesting that sFRP4 mRNA expression was accompanied by the late phase of decidual cell proliferation. Moreover, sFRP4 and estrogen receptor-alpha transcripts were co-localized. Furthermore, we analyzed the regulation of sFRP4 by estrogen using 17 beta-estradiol-treated ovariectomized rats. sFRP4 mRNA was detected in the uterus at 48 h after estrogen treatment, especially in endometrial stroma where PCNA-positive cells were also observed. The results in this study led us to the notion that sFRP4 mRNA may be up-regulated after estrogen treatment in the late phase of uterine cell proliferation.