Pharmacological doses of melatonin impede cognitive decline in tau‐related Alzheimer models,once tauopathy is initiated,by restoring the autophagic flux

Alterations in autophagy are increasingly being recognized in the pathogenesis of proteinopathies like Alzheimer's disease (AD). This study was conducted to evaluate whether melatonin treatment could provide beneficial effects in an Alzheimer model related to tauopathy by improving the autophagic flux and, thereby, prevent cognitive decline. The injection of AAV‐hTau^P301L viral vectors and treatment/injection with okadaic acid were used to achieve mouse and human ex vivo, and in vivo tau‐related models. Melatonin (10 μmol/L) impeded oxidative stress, tau hyperphosphorylation, and cell death by restoring autophagy flux in the ex vivo models. In the in vivo studies, intracerebroventricular injection of AAV‐hTau^P301L increased oxidative stress, neuroinflammation, and tau hyperphosphorylation in the hippocampus 7 days after the injection, without inducing cognitive impairment; however, when animals were maintained for 28 days, cognitive decline was apparent. Interestingly, late melatonin treatment (10 mg/kg), starting once the alterations mentioned above were established (from day 7 to day 28), reduced oxidative stress, neuroinflammation, tau hyperphosphorylation, and caspase‐3 activation; these observations correlated with restoration of the autophagy flux and memory improvement. This study highlights the importance of autophagic dysregulation in tauopathy and how administration of pharmacological doses of melatonin, once tauopathy is initiated, can restore the autophagy flux, reduce proteinopathy, and prevent cognitive decline. We therefore propose exogenous melatonin supplementation or the development of melatonin derivatives to improve autophagy flux for the treatment of proteinopathies like AD.     

LONG‐TERM FOLLOW UP OF PATIENTS WITH SMALL GASTROINTESTINAL STROMAL TUMORS IN THE STOMACH USING ENDOSCOPIC ULTRASONOGRAPHY‐GUIDED FINE‐NEEDLE ASPIRATION BIOPSY

Background: Gastrointestinal stromal tumors (GIST) are one of the most common mesenchymal tumors of the gastrointestinal tract. GIST are defined by positive immunohistochemical staining for KIT or CD34 and thus are generally diagnosed after surgery. Because small GIST are rarely diagnosed before surgery, the clinical course of these small tumors is not clear. The aim of the present study was to follow changes in size and configuration of small GIST that were pathologically confirmed using endoscopic ultrasonography‐guided fine‐needle aspiration biopsy (EUS‐FNAB). Methods: Between July 1997 and December 2003, 16 tumors in 16 patients (10 men and 6 women) with an immunohistochemical diagnosis of GIST were regularly followed in our hospital. The median patient age when EUS‐FNAB was performed was 62 years (range 26–82 years) and the median follow‐up period was 4.9 years (range 0.5–9.6 years). Results: Fourteen tumors showed no remarkable changes in size and shape during follow up compared with the initial diagnosis. Two tumors enlarged: one tumor approximately doubled its diameter in 8 years and the other tumor increased from 1.8 cm at diagnosis to up to 10 cm after only 2 years. Doubling time of the latter tumor was calculated as 3.1 months. Conclusions: We conclude that EUS‐FNAB might be a good modality for final diagnosis of GIST without surgery, and that GIST without rapid growth on follow up can be endoscopically followed.     

Overexpression of monocyte chemotactic protein-1/CCL2 in beta-amyloid precursor protein transgenic mice show accelerated diffuse beta-amyloid deposition

Microglia accumulation at the site of amyloid plaques is a strong indication that microglia play a major role in Alzheimer's disease pathogenesis. However, how microglia affect amyloid-beta peptide (Abeta) deposition remains poorly understood. To address this question, we developed a novel bigenic mouse that overexpresses both amyloid precursor protein (APP) and monocyte chemotactic protein-1 (MCP-1; CCL2 in systematic nomenclature). CCL2 expression, driven by the glial fibrillary acidic protein promoter, induced mononuclear phagocyte (MP; monocyte-derived macrophage and microglial) accumulation in the brain. When APP/CCL2 transgenic mice were compared to APP mice, a fivefold increase in Abeta deposition was present despite increased MP accumulation around hippocampal and cortical amyloid plaques. Levels of full-length APP, its C-terminal fragment, and Abeta-degrading enzymes (insulin-degrading enzyme and neprilysin) in APP/CCL2 and APP mice were indistinguishable. Sodium dodecyl sulfate-insoluble Abeta (an indicator of fibrillar Abeta) was increased in APP/CCL2 mice at 5 months of age. Apolipoprotein E, which enhances Abeta deposition, was also increased (2.2-fold) in aged APP/CCL2 as compared to APP mice. We propose that although CCL2 stimulates MP accumulation, it increases Abeta deposition by reducing Abeta clearance through increased apolipoprotein E expression. Understanding the mechanisms underlying these events could be used to modulate microglial function in Alzheimer's disease and positively affect disease outcomes.     

IMMUNOHISTOCHEMICAL DEMONSTRATION OF PEPTIDE YY IN GASTROINTESTINAL ENDOCRINE TUMORS

Fourteen cases of gastrointestinal endocrine tumors were examined im-munohistochemically for peptide YY, pancreatic polypeptide, glucagon, and somatostatin. Peptide YY cells were present in seven tumors, pancreatic polypeptide cells in eight tumors, glucagon cells in six tumors, and somatostatin cells in nine tumors. All 7 rectal endocrine tumors examined were found to contain peptide YY, while in the tumors of the other sites peptide YY cells were not detected. Peptide YY cell population in the rectal tumors was small to moderate in comparison with pancreatic polypeptide and glucagon cell population. This study suggests that peptide YY cells may be a common constituent of rectal endocrine tumors together with pancreatic polypeptide and glucagon cells, and that the peptide YY spectrum of gastrointestinal endocrine tumors may be closely related to the location of the tumors. Moreover, it can also be said that peptide YY may be used as one of the markers of rectal endocrine tumors.     

Activation of NR1a/NR2B receptors by soluble factors from APP-stimulated monocyte-derived macrophages: implications for the pathogenesis of Alzheimer's disease

Amyloid-beta peptide (Abeta), the major component of amyloid plaques, can activate brain mononuclear phagocytes (MP; macrophages and microglia), leading to their secretion of neurotoxins. Recent studies strongly suggest that MP-mediated neurotoxicity plays an important role in the pathogenesis of Alzheimer's disease (AD). To further explore this notion, human monocyte-derived macrophages (MDM) were stimulated with naturally secreted alpha-processing soluble amyloid precursor protein/p3 (alphaAPPs/p3) or beta-processing APP/Abeta (betaAPPs/Abeta). MDM conditioned media (MCM) was recovered and tested for its ability to activate recombinant N-methyl-d-aspartate (NMDA) receptor subtype NR1a/NR2B expressed in Xenopus oocytes. Pressure ejection of alphaAPPs/p3- and betaAPPs/Abeta-stimulated MCM produced inward currents of 59.5 +/- 8.9 nA (mean +/- S.E.M., n = 31) and 111.1 +/- 21.0 nA (n = 42) in NR1a/NR2B-expressing oocytes, respectively. The MCM-induced currents were concentration dependent and blocked by 50 microM of the NMDA receptor antagonist 2-amino-5-phosphnovalerate, but not by a non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (20 microM). The alphaAPPs/p3- and betaAPPs/Abeta-stimulated MCM placed in non-injected oocytes failed to generate inward current. These results demonstrate that APPs/Abeta-stimulated MCM directly activate NMDA receptor subtypes relevant in the pathogenesis of AD.     

Cardiac rhabdomyoma. A case report with reference to atrial natriuretic peptide

An autopsy case of cardiac rhabdomyoma in a male infant is reported. Many nodules of rhabdomyoma were present in all four cardiac chambers and were microscopically composed of ovoid, glycogen-laden cells and typical "spider cells". Atrial natriuretic peptide (ANP) was immunohistochemically demonstrated in both normal myocytes and rhabdomyoma cells of both atria, but not in normal myocytes and rhabdomyoma cells of both ventricles. Ultrastructurally, atrial specific granules were present in atrial rhabdomyoma cells and normal atrial cardiocytes, and these showed ANP immunoreactivity with protein A-gold technique. It could be said that the localization and intracellular distribution of ANP in this cardiac rhabdomyoma were closely similar to those of normal human heart. With regard to the presence of ANP, cardiac rhabdomyoma cells arising in atria seemed to differ from those in ventricles, although many tumor nodules occurred in both atria and ventricles. Furthermore, it seemed that cardiac rhabdomyomas could also be divided into two parts: 1) an atrial part with ANP, and 2) a ventricular part without ANP. Therefore, this study confirms the hypothesis that cardiac rhabdomyoma is a hamartoma rather than a true neoplasm.     

Interferon-gamma and tumor necrosis factor-alpha regulate amyloid-beta plaque deposition and beta-secretase expression in Swedish mutant APP transgenic mice

Reactive astrocytes and microglia in Alzheimer's disease surround amyloid plaques and secrete proinflammatory cytokines that affect neuronal function. Relationship between cytokine signaling and amyloid-beta peptide (Abeta) accumulation is poorly understood. Thus, we generated a novel Swedish beta-amyloid precursor protein mutant (APP) transgenic mouse in which the interferon (IFN)-gamma receptor type I was knocked out (APP/GRKO). IFN-gamma signaling loss in the APP/GRKO mice reduced gliosis and amyloid plaques at 14 months of age. Aggregated Abeta induced IFN-gamma production from co-culture of astrocytes and microglia, and IFN-gamma elicited tumor necrosis factor (TNF)-alpha secretion in wild type (WT) but not GRKO microglia co-cultured with astrocytes. Both IFN-gamma and TNF-alpha enhanced Abeta production from APP-expressing astrocytes and cortical neurons. TNF-alpha directly stimulated beta-site APP-cleaving enzyme (BACE1) expression and enhanced beta-processing of APP in astrocytes. The numbers of reactive astrocytes expressing BACE1 were increased in APP compared with APP/GRKO mice in both cortex and hippocampus. IFN-gamma and TNF-alpha activation of WT microglia suppressed Abeta degradation, whereas GRKO microglia had no changes. These results support the idea that glial IFN-gamma and TNF-alpha enhance Abeta deposition through BACE1 expression and suppression of Abeta clearance. Taken together, these observations suggest that proinflammatory cytokines are directly linked to Alzheimer's disease pathogenesis.     

Tau Phosphorylation is Impacted by Rare <Emphasis Type="Italic">AKAP9</Emphasis> Mutations Associated with Alzheimer Disease in African Americans

We studied the effect of two rare mutations (rs144662445 and rs149979685) in the A-kinase anchoring protein 9 (AKAP9) gene, previously associated with Alzheimer disease (AD) in African Americans (AA), on post-translational modifications of AD-related pathogenic molecules, amyloid precursor protein (APP) and microtubule-associated protein Tau using lymphoblastoid cell lines (LCLs) from 11 AA subjects with at least one AKAP9 mutation and 17 AA subjects lacking these mutations. LCLs were transduced by viral vectors expressing causative AD mutations in APP or human full-length wild type Tau. Cell lysates were analyzed for total APP, Aβ₄₀, and total and T181 phospho-Tau (pTau). AKAP9 mutations had no effect on Aβ₄₀/APP, but significantly increased pTau/Tau ratio in LCLs treated with phosphodiesterase-4 inhibitor rolipram, which activates protein kinase A. Proteomic analysis of Tau interactome revealed enrichment of RNA binding proteins and decrease of proteasomal molecules in rolipram-treated cells with AKAP9 mutations. This study shows the impact of rare functional AKAP9 mutations on Tau, a central mechanism of AD pathogenesis, in LCLs derived from AD and control subjects.     

Conversion of G-protein specificity of insulin-like growth factor II/mannose 6-phosphate receptor by exchanging of a short region with beta-adrenergic receptor.

The 14-residue peptide (peptide 14) corresponding to Arg2410-Lys2423 of the insulin-like growth factor II receptor (IGF-IIR) can activate the adenylate cyclase-inhibitor guanine nucleotide-binding protein Gi, and the 15-residue beta III-2 peptide Arg259-Lys273 of the beta 2-adrenergic receptor (beta 2AR) can activate the stimulatory protein Gs. In phospholipid vesicles, IGF-IIR and beta 2AR activate Gi and Gs in response to IGF-II and isoproterenol, respectively. We constructed a chimeric IGF-II receptor (beta III-2/IGF-IIR) by converting its native peptide 14 sequence to the beta III-2 sequence. In cells expressing beta III-2/IGF-IIR, membrane adenylate cyclase activity markedly increased without IGF-II and was further promoted by IGF-II. This was verified by measuring chloramphenicol acetyltransferase (CAT) activity in beta III-2/IGF-IIR cells with cotransfection of a cAMP response element-CAT construct. This study shows not only the conversion of G-protein specificity of a receptor from Gi to Gs but also the simulation of G protein-coupled receptor signals by using a short receptor region and intact cells. These findings indicate that the G protein-activation signals are interchangeable, self-determined structural motifs that function in the setting of either a single-spanning or multiple-spanning receptor.     

Risk of second malignancies in patients with gastric marginal zone lymphomas of mucosa associate lymphoid tissue (MALT)

Background

It is controversial whether patients with gastric marginal zone lymphomas of mucosa associated lymphoid tissue (MALT) have higher risk of second malignancies. The aim of this study was to define the risk of second malignancies in these patients.

Methods

We analyzed prospective follow-up data of 146 consecutive patients with gastric MALT lymphoma treated at Aichi Cancer Center Hospital and compared the incidence of second malignancies with that in the general population. We calculated the standardized incidence ratio (SIR), using age- and sex-specific incidence rates from the Aichi Cancer Registry.

Results

The median follow-up period was 74 months. A total of 27 tumors occurred in 22 patients (15.1 %), including 19 solid tumors. Of these, nine tumors were detected concomitantly with, and 18 tumors following, the diagnosis of gastric MALT lymphoma. Four patients had two second malignancies each. For the entire group, the SIR of an additional malignancy was 3.39 (95 % confidence interval [CI] 2.11–4.66). An increased incidence of solid tumors (SIR 2.91 [1.60–4.22]) and hematologic malignancies (SIR 5.54 [1.70–9.38]) were seen. In addition, there was increased risk for development of second malignancies during follow up (SIR 2.26 [1.21–3.30]). Chemotherapy for treatment of MALT was an independent risk factor for second malignancies (age–sex adjusted hazard ratio 3.98 [1.47–10.79].

Conclusions

Compared with the general population, patients with gastric MALT lymphoma are at increased risk for second malignancies, including gastric cancer.