Anti-oxidant effect of ascorbic and dehydroascorbic acids in hippocampal slice culture

Ascorbic acid (AA) and dehydroascorbic acid (DHA) have been shown to have protective effects as anti-oxidants in experimental neurological disorder models such as stroke, ischemia, and epileptic seizures. The present study was conducted to examine the protective effects of AA and DHA on kainic acid (KA) neurotoxicity using organotypic hippocampal slice cultures. After 12 h KA treatment, significant delayed neuronal death was detected in the CA3, but not the CA1, region. Pretreatment with intermediate doses of AA and DHA significantly prevented cell death and inhibited reactive oxygen species (ROS) level, and mitochondrial dysfunction in the CA3 region. In contrast, pretreatment with low or high doses of AA or DHA was not effective. These data suggest that pretreatment with both AA and DHA has dose-dependent neuroprotective effects on KA-induced neuronal injury through inhibiting ROS generation and mitochondrial dysfunction.     

Production of antibodies against rhodopsin after immunization with beta gamma-subunits of transducin: evidence for interaction of beta gamma-subunits of guanosine 5'-triphosphate binding proteins with receptor

The light-detecting system of retinal rod outer segments is regulated by a guanyl nucleotide binding (G) protein, transducin, which is composed of alpha-, beta-, and gamma-subunits. Transducin couples rhodopsin to the intracellular effector enzyme, a cGMP phosphodiesterase. The beta gamma complex (T beta gamma) is required for the alpha-subunit (T alpha) to interact effectively with the photon receptor rhodopsin. It is not clear, however, whether T beta gamma binds directly to rhodopsin or promotes T alpha binding to rhodopsin only by binding to T alpha. We have found that serum from rabbits immunized with T beta gamma contained a population of antibodies that were reactive against rhodopsin. These antibodies could be separated from T beta gamma antibodies by absorbing the latter on immobilized transducin. Binding of purified rhodopsin antibodies was inhibited by T beta gamma, suggesting that the rhodopsin antibodies and T beta gamma bound to the same site on rhodopsin. We propose that the rhodopsin antibodies act both as antiidiotypic antibodies against the idiotypic T beta gamma antibodies and as antibodies against rhodopsin. This hypothesis is consistent with the conclusion that T beta gamma interacts directly with the receptor. It is probable that in an analogous way, G beta gamma interacts directly with receptors of the adenylate cyclase system.     

Ten-Micrometer-Thick Si Wafers with Ag Nanoclusters: Substrate Effects on Plasmon-Enhanced Optical Absorption

We present the optical characteristics of 10-μm-thick crystalline Si wafers with an Ag heptamer nanocluster (NC) array, using a finite-difference time-domain method. The anti-reflection properties of the Ag NC array were more pronounced at long wavelengths, with respect to a monomer array, resulting in significantly enhanced optical absorption in the underlying Si wafer. The scattering cross-section spectra of the NC on the Si wafer exhibited one broad peak with a kink, whereas those in air showed two broad peaks and a sharp Fano dip between them. The high refractive index Si wafer weakened the near-field coupling between particles in the NCs, which modified the optical cross-sections of the Ag NC more drastically than those of the Ag monomer. Therefore, the implementation of the NC nanoantennae for Si-based optoelectronic devices requires careful consideration of the substrate effects.

     

Integrative pathway-based survival prediction utilizing the interaction between gene expression and DNA methylation in breast cancer

Background

Integrative analysis on multi-omics data has gained much attention recently. To investigate the interactive effect of gene expression and DNA methylation on cancer, we propose a directed random walk-based approach on an integrated gene-gene graph that is guided by pathway information.

Methods

Our approach first extracts a single pathway profile matrix out of the gene expression and DNA methylation data by performing the random walk over the integrated graph. We then apply a denoising autoencoder to the pathway profile to further identify important pathway features and genes. The extracted features are validated in the survival prediction task for breast cancer patients.

Results

The results show that the proposed method substantially improves the survival prediction performance compared to that of other pathway-based prediction methods, revealing that the combined effect of gene expression and methylation data is well reflected in the integrated gene-gene graph combined with pathway information. Furthermore, we show that our joint analysis on the methylation features and gene expression profile identifies cancer-specific pathways with genes related to breast cancer.

Conclusions

In this study, we proposed a DRW-based method on an integrated gene-gene graph with expression and methylation profiles in order to utilize the interactions between them. The results showed that the constructed integrated gene-gene graph can successfully reflect the combined effect of methylation features on gene expression profiles. We also found that the selected features by DA can effectively extract topologically important pathways and genes specifically related to breast cancer.

     

High level activation of vitamin B1 biosynthesis genes in haustoria of the rust fungus Uromyces fabae

In the rust fungus Uromyces fabae, the transition from the early stages of host plant invasion toward parasitic growth is accompanied by the activation of many genes (PIGs = in planta induced genes). Two of them, PIG1 (= THI1) and PIG4 (= THI2), were found to be highly transcribed in haustoria, and are homologous to genes involved in thiamine (vitamin B1) biosynthesis in yeast. Their functional identity was confirmed by complementation of Schizosaccharomyces pombe thiamine auxotrophic thi3 (nmt1) and thi2 (nmt2) mutants, respectively. In contrast to thiamine biosynthesis genes of other fungi that are completely suppressed by thiamine, THI1 and THI2 expression was not affected by the addition of thiamine to rust hyphae grown either in vitro or in planta. Immunoblot analysis revealed decreasing amounts of THI1p in extracts from spores, germlings, and in vitro-grown infection structures with increasing time after inoculation. Immunofluorescence microscopy of rust-infected leaves detected high concentrations of THI1p in haustoria, and only low amounts in intercellular hyphae. In the sporulating mycelium, THI1p was found in the basal hyphae of the uredia, but not in the pedicels and only at very low levels in uredospores. These data indicate that the haustorium is an essential structure of the biotrophic rust mycelium not only for nutrient uptake but also for the biosynthesis of metabolites such as thiamine.     

Contrast-Enhanced FLAIR (Fluid-Attenuated Inversion Recovery) for Evaluating Mild Traumatic Brain Injury

Purpose

To evaluate whether adding a contrast-enhanced fluid-attenuated inversion recovery (FLAIR) sequence to routine magnetic resonance imaging (MRI) can detect additional abnormalities in the brains of symptomatic patients with mild traumatic brain injury.

Materials and Methods

Fifty-four patients with persistent symptoms following mild closed head injury were included in our retrospective study (M∶F = 32∶22, mean age: 59.8±16.4, age range: 26–84 years). All MRI examinations were obtained within 14 days after head trauma (mean: 3.2±4.1 days, range: 0.2–14 days). Two neuroradiologists recorded (1) the presence of traumatic brain lesions on MR images with and without contrast-enhanced FLAIR images and (2) the pattern and location of meningeal enhancement depicted on contrast-enhanced FLAIR images. The number of additional traumatic brain lesions diagnosed with contrast-enhanced FLAIR was recorded. Correlations between meningeal enhancement and clinical findings were also evaluated.

Results

Traumatic brain lesions were detected on routine image sequences in 25 patients. Three additional cases of brain abnormality were detected with the contrast-enhanced FLAIR images. Meningeal enhancement was identified on contrast-enhanced FLAIR images in 9 cases while the other routine image sequences showed no findings of traumatic brain injury. Overall, the additional contrast-enhanced FLAIR images revealed more extensive abnormalities than routine imaging in 37 cases (p<0.001). In multivariate logistic regression analysis, subdural hematoma and posttraumatic loss of consciousness showed a significant association with meningeal enhancement on contrast-enhanced FLAIR images, with odds ratios 13.068 (95% confidence interval 2.037 to 83.852), and 15.487 (95% confidence interval 2.545 to 94.228), respectively.

Conclusion

Meningeal enhancement on contrast-enhanced FLAIR images can help detect traumatic brain lesions as well as additional abnormalities not identified on routine unenhanced MRI. Therefore contrast-enhanced FLAIR MR imaging is recommended when a contrast MR study is indicated in a patient with a symptomatic prior closed mild head injury.     

Folic Acid Supplementation Promotes Mammary Tumor Progression in a Rat Model

Folic acid supplementation may prevent the development of cancer in normal tissues but may promote the progression of established (pre)neoplastic lesions. However, whether or not folic acid supplementation can promote the progression of established (pre)neoplastic mammary lesions is unknown. This is a critically important issue because breast cancer patients and survivors in North America are likely exposed to high levels of folic acid owing to folic acid fortification and widespread supplemental use after cancer diagnosis. We investigated whether folic acid supplementation can promote the progression of established mammary tumors. Female Sprague-Dawley rats were placed on a control diet and mammary tumors were initiated with 7,12-dimethylbenza[a]anthracene at puberty. When the sentinel tumor reached a predefined size, rats were randomized to receive a diet containing the control, 2.5x, 4x, or 5x supplemental levels of folic acid for up to 12 weeks. The sentinel mammary tumor growth was monitored weekly. At necropsy, the sentinel and all other mammary tumors were analyzed histologically. The effect of folic acid supplementation on the expression of proteins involved in proliferation, apoptosis, and mammary tumorigenesis was determined in representative sentinel adenocarcinomas. Although no clear dose-response relationship was observed, folic acid supplementation significantly promoted the progression of the sentinel mammary tumors and was associated with significantly higher sentinel mammary tumor weight and volume compared with the control diet. Furthermore, folic acid supplementation was associated with significantly higher weight and volume of all mammary tumors. The most significant and consistent mammary tumor-promoting effect was observed with the 2.5x supplemental level of folic acid. Folic acid supplementation was also associated with an increased expression of BAX, PARP, and HER2. Our data suggest that folic acid supplementation may promote the progression of established mammary tumors. The potential tumor-promoting effect of folic acid supplementation in breast cancer patients and survivors needs further clarification.     

Lithium chloride inhibits TGF-β1-induced myofibroblast transdifferentiation via PI3K/Akt pathway in cultured fibroblasts from Tenon’s capsule of the human eye

Excess scarring of the conjunctiva after glaucoma filtration surgery is a major cause of failure. Transforming growth factor (TGF)-β is critically involved in post-operative scarring. Lithium inhibits TGF-β-induced gene protein expression in corneal fibroblasts and inhibits TGF-β-induced epithelial mesenchymal transition. Here, we investigated the effects of LiCl on TGF-β1-mediated signaling pathways and on myofibroblast transdifferentiation of human Tenon’s capsule fibroblasts (HTFs). LiCl treatment reduced expression of TGF-β1-induced α-SMA expression in HTFs. LiCl also decreased Akt phosphorylation induced by TGF-β1. TGF-β1-induced α-SMA expression was significantly decreased by LY294002 and Akt siRNA indicating that these changes are mediated by the PI3K/Akt pathway. Thus, LiCl induces the suppression of transdifferentiation stimulated by TGF-β1 by the regulation of PI3K/Akt signaling in HTFs.     

Guinea pig anaphylaxis: time course of changes in cyclic AMP and cyclic GMP.

The time course of changes in the levels of cyclic AMP and GMP and in histamine and prostaglandin release following the onset of anaphylaxis in guinea pig lung (sliced, minced and whole perfused) was studied. A parallel change in the cyclic nucleotide levels was found. There was an initial increase, followed by a decrease, and a subsequent greater and more prolonged increase. Significant histamine and prostaglandin release occurs at approximately the same time while prostaglandin metabolite is released later. Metiamide does not affect histamine or prostaglandin release but abolishes the initial cyclic nucleotide peak and delays the appearance of the secondary increase. The pattern of cyclic nucleotide changes in lung tissue thus appears to be different from that in isolated mast cells. The initial and late increases might be the response of two different cell populations to histamine.