Argyrophilic grain disease and Alzheimer's disease are distinguished by their different distribution of tau protein isoforms

Prominent neuronal and glial tau filamentous inclusions are hallmarks of neurodegenerative tauopathies, among them Alzheimer's disease (AD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Pick's disease (PiD), and argyrophilic grain disease (AgD). AgD is a late onset dementia in which pathologically aggregated tau proteins are found in limbic structures in the shape of distinct argyrophilic grains and coiled bodies. Until now tau protein deposits in AgD have not been assessed biochemically. We therefore decided to investigate the electrophoretic profile of pathological tau protein as well as the tau protein isoform composition of filamentous inclusions in AgD cases. A distinct pathological tau doublet at 64 and 69 kDa and a minor 74-kDa band was obtained in two AgD cases with only very mild concomitant AD pathology (Braak stage I), while in two AgD cases with moderate AD pathology (Braak stage II and III, respectively), an additional minor band at 60 kDa was detected. Thus, the pathological tau profile (PTP) in pure AgD cases differs from both the PTPs in AD (tau triplet at 60, 64 and 69 kDa, minor band at 74 kDa) and PiD (major tau doublet at 60 and 64 kDa, minor band at 69 kDa) but not from those in PSP and CBD. Using a two-dimensional gel electrophoresis approach anti-exon 10 antiserum strongly stained the AgD doublet and the minor 74-kDa band, while anti-exon 2 and 3 antisera only faintly stained the 69- and the minor 74-kDa component, thus suggesting that pathological tau aggregates in AgD are mainly made of four-repeat (4R) tau isoforms. Furthermore, in contrast to earlier immunohistochemical studies, we now show biochemically that Ser262 indeed is phosphorylated in the PTP of AgD. Finally, expression of normal tau protein was not found to be altered in AgD. Altogether, our results demonstrate that AgD is characterized by a major tau doublet that is distinct from AD and PiD. AgD, however, shares the pathological tau doublet (64 and 69 kDa) as well as the predominance of 4R tau isoforms with CBD and PSP.     

Effect of chronic phenobarbital administration on the gamma-glutamyl transpeptidase activity of hyperplastic liver lesions induced in rats by the Solt/Farber initiation: selection process of hepatocacinogenesis

A chronic 8 to 11 week administration of the hepatic tumor promoterphenobarbital (0.05% in drinking water) to rats previously subjectedto the initiation:selection process of Solt and Farber was foundto further increase the gamma-glutamyl transpeptidase activityof individual hyperplastic liver nodules of 4.0–10.0 mmin diameter over comparably sized nodules form control livers.Those rats which received 11 weeks of the chronic phenobarbitaltreatment also showed a significant increase in their liverwet weights. In addition, random tissue samples of non-nodularliver taken from the 11 week phenobarbital-treated rats exhibiteda gamma-glutamyl transpeptidase mean specific activity whichwas {small tilde}3 times higher than that of control non-nodularliver samples. In contrast, there was a 1.9-fold increase inthe mean % gamma-glutamyl transpeptidase-positive area (cm²),as determined histochemically, in cryostat sections made fromnon-nodular samples of the 11 week phenobarbital-treated ratswhen compared with that of control liver sections. Interruptionof the chronic phenobarbital administration at 8 weeks followedby 3 weeks of control treatment resulted in a reversal of thegammaglutamyl transpeptidase activity response shown by thehyperplastic liver nodules and non-nodular liver tissue samples.Thus, phenobarbital can quantitatively modulate gamma-glutamyltranspeptidase activity in carcinogeninduced hyperplastic liverlesions in the rat during the early stages of hepatocarcinogenesis.     

Comparison of methods used to study cell death in an adherent tumoral cell line with moderate clonogenic radiosensitivity

Our objective was to compare different methods for studying programmed cell death in adherent H460 non-small lung cancer cells of moderate clonogenic radiosensitivity. The major effect of gamma-radiation was found to be the release of cells from the substratum. The different methods gave complementary and unexpected information: a) with the TUNEL method, a few non-apoptotic cells were found in the culture medium; b) with the flow cytometry after propidium iodide labeling, some hypodiploid cells which remained attached to the substratum were apoptotic, as demonstrated by the effect of a caspase inhibitor; c) with the annexin V labeling, the detached cells were demonstrated either necrotic or very late apoptotic; d) the mitochondria transmembrane potential (deltapsim), measurements demonstrated that the mitochondria were implicated in cell death induced by gamma-radiation. These data illustrate the need to use several complementary methods in the study of apoptosis in adherent cells exposed to gamma-radiation.     

A multidisciplinary approach to the study of the fluminense vegetation

The fluminense vegetation, more specifically the flora from the Jurubatiba restinga has been investigated by a multidisciplinary team of botanists, chemist, radiobiologist, insect physiologists and geneticist. Vouchers of 564 specimens have been collected, identified, organized in an herbarium, and a database is being build up containing, in addition to classical botanical data, chemical data and information on the potential economic use either for landscape gardening, alternative foods or as medicinal plants. Phytochemical studies of the Guttiferae, Clusia hilariana, yielded oleanolic acid and nemorosone. Their biological activities against the haematophagous insect Rhodnius prolixus vector of Chagas disease have been investigated. Finally, it has been observed that aquatic plants possessed high levels of the natural radionuclide polonium-210, which seems to be originated mainly from soil rather than from atmospheric supply.     

Ceramide induces activation of the mitochondrial/caspases pathway in Jurkat and SCC61 cells sensitive to gamma-radiation but activation of this sequence is defective in radioresistant SQ20B cells

PURPOSE: To clarify the molecular mechanisms leading to radiation-induced apoptosis or resistance, the kinetics (1-48 h) and sequence of events triggered in response to 10 Gy irradiation were investigated in three cell lines displaying a gradient of sensitivity to 7-rays. MATERIALS AND METHODS: Ceramide levels were measured by high performance liquid chromatography (HPLC). Mitochondrial function was evaluated in terms of transmembrane potential (delta(psi)m), reactive oxygen species (ROS) and glutathione levels analysed by flow cytometry or HPLC. Caspase activation was assessed by immunoblotting, and apoptosis by flow cytometry. RESULTS: In Jurkat radiosensitive cells and SCC61 adherent cells with intermediate radiosensitivity, the degree of delayed ceramide release was directly related to their propensity to undergo apoptosis. Transduction of the death signal was mediated by a drop in delta(psi)m and glutathione levels, ROS accumulation and activation of effector caspases. Experiments conducted with caspase inhibitors, bongkrekic acid, or DL-PDMP indicated that ceramide triggers mitochondrial collapse, followed by the activation of caspases-9, -8 and -3, and poly(ADP-ribose)polymerase cleavage. In SQ20B radioresistant cells, gamma-radiation did not induce ceramide generation or subsequent activation of the mitochondrial/caspase apoptotic pathway. CONCLUSIONS: Ceramide appears to be a determining factor in the commitment phase of radiation-induced apoptosis. When ceramide is not generated, the whole pathway is ineffective and resistance to apoptosis may result.     

Differential expression and functional role of cannabinoid genes in alcohol users

Background

Genetic factors account for about fifty percent of the risk for alcoholism and alcohol dependence (AD) has been reported to be influenced by cannabinoid receptors (CBRs) and the endocannabinoid system (ECS). Previous studies have focused on cannabinoids and alcohol-related effects in the CNS; however, the role CBRs play on alcohol effects in the immune system has not been elucidated yet. Since alcohol can affect immune responses and have detrimental effects on immune cells such as dendritic cells (DCs), we hypothesize that alcohol can exert its effects on DCs by modulating changes in CBRs, which in turn can regulate important DC functions such as cytokine production.

Methods

Therefore, we studied the expression of CNR1 and CNR2, and the novel cannabinoid G protein-coupled receptor (GPCR) 55 (GPR55) in human monocyte-derived dendritic cells (MDDCs) from alcohol users. CNR1, CNR2, and GPR55 genes were measured by qRT-PCR and protein by flow cytometry. MDDCs from alcohol users show significantly higher levels of CNR2 and GPR55 compared to MDDCs from non-users. These findings were further confirmed using MDDCs treated with alcohol. Inflammatory cytokines were measured in EtOH-treated and non-treated cells by antibody array.

Results

Functional effects of CBRs on MDDCs were shown by CB2 and GPR55 siRNA transfection. Transfected EtOH-treated cells showed significantly higher levels of proinflammatory cytokine production as measured by IL-1β expression. Our results provide insights into alcohol mechanisms of DC regulation and show, for the first time, that alcohol is inducing CNR2 and GPR55 in human DCs.     

High Rate of Simian Immunodeficiency Virus (SIV) Infections in Wild Chimpanzees in Northeastern Gabon

The emergence of HIV-1 groups M, N, O, and P is the result of four independent cross-species transmissions between chimpanzees (cpz) and gorillas (gor) from central/south Cameroon and humans respectively. Although the first two SIVcpz were identified in wild-born captive chimpanzees in Gabon in 1989, no study has been conducted so far in wild chimpanzees in Gabon. To document the SIVcpz infection rate, genetic diversity, and routes of virus transmission, we analyzed 1458 faecal samples collected in 16 different locations across the country, and we conducted follow-up missions in two of them. We found 380 SIV antibody positive samples in 6 different locations in the north and northeast. We determined the number of individuals collected by microsatellite analysis and obtained an adjusted SIV prevalence of 39.45%. We performed parental analysis to investigate viral spread between and within communities and found that SIVs were epidemiologically linked and were transmitted by both horizontal and vertical routes. We amplified pol and gp41 fragments and obtained 57 new SIVcpzPtt strains from three sites. All strains, but one, clustered together within a specific phylogeographic clade. Given that these SIV positive samples have been collected nearby villages and that humans continue to encroach in ape’s territories, the emergence of a new HIV in this area needs to be considered.