Regulation of DJ-1 by glutaredoxin 1 \u3ci\u3ein vivo – implications for Parkinson’s disease\u3c/i\u3e

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide, caused by the degeneration of the dopaminergic neurons in the substantia nigra. Mutations in PARK7 (DJ-1) result in early onset autosomal recessive PD, and oxidative modification of DJ-1 has been reported to regulate the protective activity of DJ-1 in vitro. Glutathionylation is a prevalent redox modification of proteins resulting from the disulfide adduction of the glutathione moiety to a reactive cysteine-SH; and glutathionylation of specific proteins has been implicated in regulation of cell viability. Glutaredoxin 1 (Grx1) is the principal deglutathionylating enzyme within cells, and it has been reported to mediate protection of dopaminergic neurons in C. elegans, however many of the functional downstream targets of Grx1 in vivo remain unknown. Previously, DJ-1 protein content was shown to decrease concomitantly with diminution of Grx1 protein content in cell culture of model neurons (SH-SY5Y and Neuro-2A lines). In the current study we aimed to investigate the regulation of DJ-1 by Grx1 in vivo and characterize its glutathionylation in vitro. Here, with Grx−/− mice we provide evidence that Grx1 regulates protein levels of DJ-1 in vivo. Furthermore, with model neuronal cells (SH-SY5Y) we observed decreased DJ-1 protein content in response to treatment with known glutathionylating agents; and with isolated DJ-1 we identified two distinct sites of glutathionylation. Finally, we found that overexpression of DJ-1 in the dopaminergic neurons partly compensates for the loss of the Grx1 homolog in a C. elegans in vivo model of PD. Therefore; our results reveal a novel redox modification of DJ-1 and suggest a novel regulatory mechanism for DJ-1 content in vivo

Pediatric malignancies presenting as a possible infectious disease

<p>Abstract</p> <p>Background</p> <p>The clinical, laboratory, and radiological features of malignancy can overlap with those of infection. The purpose of this study was to determine the findings in children who were initially thought to have an infectious disease but ultimately proved to have a malignancy.</p> <p>Methods</p> <p>The database of patients diagnosed with a malignancy in the Northern Alberta Children's Cancer Program (NACCP) January 1, 1993 to December 31, 2003 was merged with the database of inpatients referred to the infectious diseases service at the Stollery Children's Hospital and charts were reviewed on all patients referred to the infectious diseases consult service prior to the diagnosis of malignancy.</p> <p>Results</p> <p>An infectious diseases consultation for diagnosis was requested in 21 of 561 patients prior to the confirmation of malignancy, and 3 of these 21 patients had both infection and malignancy (leukemia (N = 13), lymphoma (N = 3), rhabdomyosarcoma (N = 1), Langerhan's cell histiocytosis (N = 1), fibrous histicocytosis (N = 1), ependymoma (N = 1), and neuroblastoma (N = 1). The most common reason for infectious diseases consultation was suspected muskuloskeletal infection (N = 9). A palpable or radiographically enlarged spleen was noted in 11 patients (52%). All but 2 patients had abnormal hematologic parameters while an elevated lactate dehydrogenase (LDH) occurred in 10 patients (48%). Delay of diagnosis because of investigation or therapy for an infectious disease occurred in only 2 patients.</p> <p>Conclusion</p> <p>It is not common for treatment of pediatric malignancies to be delayed because infection is thought to be the primary diagnosis. However, pediatric infectious diseases physicians should consider malignancy in the differential diagnosis when they see patients with fever and bone pain, unexplained splenomegaly or abnormal complete blood cell counts. Other clues may include hepatomegaly or elevated LDH.</p

Stochastic light concentration from 3D to 2D reveals ultraweak chemi- and bioluminescence

For countless applications in science and technology, light must be concentrated, and concentration is classically achieved with reflective and refractive elements. However, there is so far no efficient way, with a 2D detector, to detect photons produced inside an extended volume with a broad or isotropic angular distribution. Here, with theory and experiment, we propose to stochastically transform and concentrate a volume into a smaller surface, using a high- albedo Ulbricht cavity and a small exit orifice through cavity walls. A 3D gas of photons produced inside the cavity is transformed with a 50% number efficiency into a 2D Lambertian emitting orifice with maximal radiance and a much smaller size. With high-albedo quartz-powder cavity walls ( P = 99.94%), the orifice area is 1/( 1 - P) approximate to 1600 times smaller than the walls&apos; area. When coupled to a detectivity-optimized photon-counter ( D = 0.015 photon- 1 s1/ 2 cm) the detection limit is 110 photon s- 1 L- 1. Thanks to this unprecedented sensitivity, we could detect the luminescence produced by the non-catalytic disproportionation of hydrogen peroxide in pure water, which has not been observed so far. We could also detect the ultraweak bioluminescence produced by yeast cells at the onset of their growth. Our work opens new perspectives for studying ultraweak luminescence, and the concept of stochastic 3D/2D conjugation should help design novel light detection methods for large samples or diluted emitters

Biocompatibility of oxygen-plasma-treated polystyrene substrates

The biocompatibility of polystyrene (PS) samples has been improved by treatment with weakly ionized highly non-equilibrium oxygen plasma. Samples were exposed to plasma for 30 s for which they have received a dose of ions of 4.5 × 1017 m−2 and a neutral oxygen atom dose of 3 × 10−23 m−2. Both untreated and plasma-treated samples were tested for biocompatibility according to the same procedure. Proliferation of human mammary epithelial cells (HMECs) on samples revealed a dramatically improved biocompatibility of polystyrene treated by oxygen plasma. The HMECs were deposited on all samples and incubated for 1, 2 and 6 days. MTT test revealed about two times higher activity of cell enzymes after 48 h incubation. The activity for plasma-treated samples remained much higher than for untreated samples even after 6 days of incubation when the samples were already covered with a dense film of HMECs

Biophysical Analyses of Synthetic Amyloid-β(1-42) Aggregates before and after Covalent Cross-Linking. Implications for Deducing the Structure of Endogenous Amyloid-β Oligomers

A neuropathological hallmark of Alzheimer’s disease (AD) is the presence of large numbers of senile plaques in the brain. These deposits are rich in fibrils that are composed of 40- and 42-residue amyloid-β (Aβ) peptides. Several lines of evidence indicate that soluble Aβ aggregates as well as fibrils are important in the etiology of AD. Low levels of endogenous soluble Aβ aggregates make them difficult to characterize, but several species in extracts of AD brains have been detected by gel electrophoresis in sodium dodecyl sulfate (SDS) and immunoblotting. Individual Aβ oligomers ranging in size from dimers through dodecamers of 4 kDa monomeric Aβ have been resolved in other laboratories as discrete species by size exclusion chromatography (SEC). In an effort to reconstitute soluble Aβ aggregates in vitro that resemble the endogenous soluble Aβ aggregates, we previously found that monomeric Aβ(1−42) rapidly forms soluble oligomers in the presence of dilute SDS micelles. Here we extend this work in two directions. First, we contrast the size and secondary structure of these oligomers with those of synthetic Aβ(1−42) fibrils. SEC and multiangle light scattering were used to obtain a molecular mass of 150 kDa for the isolated oligomers. The oligomers partially dissociated to monomers through nonamers when incubated with SDS, but in contrast to endogenous oligomers, we saw no evidence of these discrete species prior to SDS treatment. One hypothesis to explain this difference is that endogenous oligomers are stabilized by covalent cross-linking induced by unknown cellular agents. To explore this hypothesis, optimal mass spectrometry (MS) analysis procedures need to be developed for Aβ cross-linked in vitro. In our second series of studies, we began this process by treating monomeric and aggregated Aβ(1−42) with three cross-linking agents: transglutaminase, glutaraldehyde, and Cu(II) with peroxide. We compared the efficiency of covalent cross-linking with these agents, the effect of cross-linking on peptide secondary structure, the stability of the cross-linked structures to thermal unfolding, and the sites of peptide cross-linking obtained from proteolysis and MS

Reversible structural transition in monocrystalline Ni2FeGaNi_{2}FeGa microwires for shape-memory applications

We report on the production and characterization of Heusler-based Ni$_2$FeGa microwires exhibiting two – wayshape memory effect. The microwires are characterized by a monocrystalline structure with a strong preferredcrystallographic orientation that shows [1 1 1] axis parallel to the wire’s axis for high-temperature L2$_1$ austenitephase, while the [0 1 7] axis is preferred for low-temperature monoclinic phase. Variation of crystallographicaxis (and corresponding easy magnetization axis) leads to 1600% variation of magnetic permeability due to a 2%strain in axial direction. Such straining is reversible immediately after production without the necessity of furtherthermal treatment. These properties give the microwire function of very sensitive SMART actuators that can beeasily produced in a large amount

Structural characterisation of Cu-Zr thin film combinatorial libraries with synchrotron radiation at the limit of crystallinity

We report for the first-time combinatorial synthesis of thin film metallic glass libraries via magnetron co-sputtering at the limit of crystallinity. Special care was taken to prepare extremely pure CuZr films (1–2 µm thickness) with large compositional gradients (Cu18.2Zr81.8 to Cu74.8Zr25.2) on X-ray transparent polymer substrates in high-vacuum conditions. Combined mapping of atomic structure (synchrotron radiation) and chemical composition (X-ray fluorescence spectroscopy) revealed that over the entire composition range, covering multiple renowned glass formers, two phases are present in the film. Our high-resolution Synchrotron approach identified the two phases as: untextured amorphous Cu51Zr14 (cluster size 1.3 nm) and textured, nanocrystalline α-Zr (grain size 1–5 nm). Real space HR-STEM analyses of a representative composition substantiate our XRD results. Determined cluster and grain sizes are below the resolution limit of conventional laboratory-scale X-ray diffractometers. The presented phase mixture is not permitted in the Cu-Zr phase diagram and contrary to existing literature. The phase ratio follows a linear trend with amorphous films on the Cu-rich side and increasing amounts of α-Zr with increasing Zr content. While cluster size and composition of the amorphous phase remain constant thorough the compositional gradient, crystallite size and texture of the nanocrystalline α-Zr change as a function of Zr content