Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

Purpose

Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens.

Methods

Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10∶14 light∶dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5), 2 hours (n = 5), 5 hours (n = 4) or 10 hours (n = 4). Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7), 30 minutes (n = 8), 15 minutes (n = 6), 7 minutes (n = 7) or 1 minute (n = 7) periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA.

Results

Compared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1∶1 or 7∶7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development.

Conclusions

The protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1∶1 min) provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.     

Productive infection of bovine papillomavirus type 2 in the placenta of pregnant cows affected with urinary bladder tumors

Papillomaviruses (PVs) are believed to be highly epitheliotropic as they usually establish productive infections within stratified epithelia. In vitro, various PVs appear to complete their entire life-cycle in different trophoblastic cell lines. In this study, infection by and protein expression of bovine papillomavirus type 2 (BPV-2) in the uterine and chorionic epithelium of the placenta has been described in four cows suffering from naturally occurring papillomavirus-associated urothelial bladder tumors. E5 oncoprotein was detected both by Western blot analysis and immunohistochemically. It appears to be complexed and perfectly co-localized with the activated platelet-derived growth factor ß receptor (PDGFßR) by laser scanning confocal microscopy. The activated PDGFßR might be involved in organogenesis and neo-angiogenesis rather than in cell transformation during pregnancy. The major capsid protein, L1, believed to be only expressed in productive papillomavirus infection has been detected by Western blot analysis. Immunohistochemical investigations confirmed the presence of L1 protein both in the cytoplasm and nuclei of cells of the uterine and chorionic epithelium. Trophoblastic cells appear to be the major target for L1 protein expression. Finally, the early protein E2, required for viral DNA replication and known to be expressed during a productive infection, has been detected by Western blot and immunohistochemically. Electron microscopic investigations detected viral particles in nuclei of uterine and chorionic epithelium. This study shows that both active and productive infections by BPV-2 in the placenta of pregnant cows can occur in vivo.     

Methylselenol Formed by Spontaneous Methylation of Selenide Is a Superior Selenium Substrate to the Thioredoxin and Glutaredoxin Systems

Naturally occurring selenium compounds like selenite and selenodiglutathione are metabolized to selenide in plants and animals. This highly reactive form of selenium can undergo methylation and form monomethylated and multimethylated species. These redox active selenium metabolites are of particular biological and pharmacological interest since they are potent inducers of apoptosis in cancer cells. The mammalian thioredoxin and glutaredoxin systems efficiently reduce selenite and selenodiglutathione to selenide. The reactions are non-stoichiometric aerobically due to redox cycling of selenide with oxygen and thiols. Using LDI-MS, we identified that the addition of S-adenosylmethionine (SAM) to the reactions formed methylselenol. This metabolite was a superior substrate to both the thioredoxin and glutaredoxin systems increasing the velocities of the nonstoichiometric redox cycles three-fold. In vitro cell experiments demonstrated that the presence of SAM increased the cytotoxicity of selenite and selenodiglutathione, which could neither be explained by altered selenium uptake nor impaired extra-cellular redox environment, previously shown to be highly important to selenite uptake and cytotoxicity. Our data suggest that selenide and SAM react spontaneously forming methylselenol, a highly nucleophilic and cytotoxic agent, with important physiological and pharmacological implications for the highly interesting anticancer effects of selenium.     

Determination of deoxynivalenol-sulfonate (DONS) in cereals by hydrophilic interaction chromatography coupled to tandem mass spectrometry

Deoxynivalenol (DON) is one of most widespread mycotoxins in cereal commodities, and animal feed is prevalently contaminated at high concentrations. This poses a problem in animal nutrition as especially pigs are very sensitive to DON. An effective process for the reduction of the DON concentration is the treatment of contaminated feed with sodium bisulfite (SBS) whereby DON is transformed into DON-sulfonate (DONS). Although the success of this treatment has been confirmed in several feeding studies, it is unexplained if the decrease of DON is accompanied with a coincident increase of DONS. For this reason, we developed a method for the analysis of DONS using hydrophilic interaction chromatography coupled to tandem mass spectrometry. In order to investigate the correlation between DON and DONS concentrations during SBS-treatment, DON-contaminated wheat was treated with SBS and stored for up to 36 days. At defined timepoints of this treatment, samples were analyzed for DON and DONS using stable isotope labeled standards. The preparation, purification, and structure elucidation of DONS, and the HILIC-HPLC-MS/MS method for the analysis of DONS as well as the results of two storage experiments are presented in this paper.     

Humoral immune responses against the immature laminin receptor protein show prognostic significance in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. The role of an autologous tumor-specific immune control contributing to the variable length of survival in CLL is poorly understood. We investigated whether humoral immunity specific for the CLL-associated Ag oncofetal Ag/immature laminin receptor (OFA/iLR) has a prognostic value in CLL. Among sera of 67 untreated patients with CLL, 23 (34.3%) had detectable OFA/iLR Abs that were reactive for at least one specific OFA/iLR epitope. Patients with humoral responses compared with patients with nonreactive sera had a longer progression-free survival (p = 0.029). IgG subclass analyses showed a predominant IgG1 and IgG3 response. OFA/iLR Abs were capable of recognizing and selectively killing OFA/iLR-expressing CLL cells in complement-mediated and Ab-dependent cellular cytotoxicity assays. In the analysis of 11 CLL patients after allogeneic hematopoietic stem cell transplantation, 8 showed high values for OFA/iLR Abs that specifically recognized the extracellular domain of the protein, suggesting a potential role of anti-OFA/iLR-directed immune responses to the graft-vs-leukemia effect in CLL. Our data suggest that spontaneous tumor-specific humoral immune responses against OFA/iLR exist in a significant proportion of CLL patients and that superior progression-free survival in those patients could reflect autologous immune control.     

Effect of ectomycorrhizal fungi on nitrogen mineralisation and the growth of Scots pine seedlings in natural peat

The aim of this study was to investigate the potential of different isolates of ectomycorrhizal (EM) fungi to enhance the growth of Pinus sylvestris seedlings in five natural peat substrates with different nitrogen concentrations, and the effect of the Scots pine seedlings and fungal inoculum on the formation of dissolved inorganic and organic nitrogen in peat. Utilization of different organic nitrogen compounds by microbial community in the peat was also investigated using Biolog MT MicroPlates. Inoculation of the seedlings with EM fungi enhanced seedling growth. Piloderma croceum increased root growth especially, whereas Lactarius rufus increased needle growth and Suillus variegatus I, II and III improved both root and needle growth. All the EM fungi also significantly affected stem growth. Nitrogen concentration of the peat did not affect seedling growth as much as the EM fungi. At the lowest peat N concentration (1.17%) NH ₄ ⁺ mineralisation was lower and DON (dissolved organic nitrogen) accumulation higher than at higher peat N concentrations. The EM fungal isolates had different effects on NH ₄ ⁺ and DON accumulation/degradation in peat. The EM fungal isolates significantly increased NH ₄ ⁺ formation in the peat, whereas L. rufus and P. croceum had an opposite effect on DON accumulation. S. variegatus I significantly decreased the DON concentrations during peat incubation. The N concentration of the peat slightly affected the utilization of amino acids and polyamines by the microbial community, whereas inoculation with S. variegatus I, II or III had no effect.     

Rab7b modulates autophagic flux by interacting with Atg4B

Autophagy (macroautophagy) is a highly conserved eukaryotic degradation pathway in which cytosolic components and organelles are sequestered by specialized autophagic membranes and degraded through the lysosomal system. The autophagic pathway maintains basal cellular homeostasis and helps cells adapt during stress; thus, defects in autophagy can cause detrimental effects. It is therefore crucial that autophagy is properly regulated. In this study, we show that the cysteine protease Atg4B, a key enzyme in autophagy that cleaves LC3, is an interactor of the small GTPase Rab7b. Indeed, Atg4B interacts and co‐localizes with Rab7b on vesicles. Depletion of Rab7b increases autophagic flux as indicated by the increased size of autophagic structures as well as the magnitude of macroautophagic sequestration and degradation. Importantly, we demonstrate that Rab7b regulates LC3 processing by modulating Atg4B activity. Taken together, our findings reveal Rab7b as a novel negative regulator of autophagy through its interaction with Atg4B.