Arginine cofactors on the polymerase ribozyme

The RNA world hypothesis states that the early evolution of life went through a stage in which RNA served both as genome and as catalyst. The central catalyst in an RNA world organism would have been a ribozyme that catalyzed RNA polymerization to facilitate self-replication. An RNA polymerase ribozyme was developed previously in the lab but it is not efficient enough for self-replication. The factor that limits its polymerization efficiency is its weak sequence-independent binding of the primer/template substrate. Here we tested whether RNA polymerization could be improved by a cationic arginine cofactor, to improve the interaction with the substrate. In an RNA world, amino acid-nucleic acid conjugates could have facilitated the emergence of the translation apparatus and the transition to an RNP world. We chose the amino acid arginine for our study because this is the amino acid most adept to interact with RNA. An arginine cofactor was positioned at ten different sites on the ribozyme, using conjugates of arginine with short DNA or RNA oligonucleotides. However, polymerization efficiency was not increased in any of the ten positions. In five of the ten positions the arginine reduced or modulated polymerization efficiency, which gives insight into the substrate-binding site on the ribozyme. These results suggest that the existing polymerase ribozyme is not well suited to using an arginine cofactor.     

Gut integrity and duodenal enteropathogen burden in undernourished children with environmental enteric dysfunction

Environmental enteric dysfunction (EED) is a subclinical condition of intestinal inflammation, barrier dysfunction and malabsorption associated with growth faltering in children living in poverty. This study explores association of altered duodenal permeability (lactulose, rhamnose and their ratio) with higher burden of enteropathogen in the duodenal aspirate, altered histopathological findings and higher morbidity (diarrhea) that is collectively associated with linear growth faltering in children living in EED endemic setting. In a longitudinal birth cohort, 51 controls (WHZ > 0, HAZ > −1.0) and 63 cases (WHZ< -2.0, refractory to nutritional intervention) were recruited. Anthropometry and morbidity were recorded on monthly bases up to 24 months of age. Dual sugar assay of urine collected after oral administration of lactulose and rhamnose was assessed in 96 children from both the groups. Duodenal histopathology (n = 63) and enteropathogen analysis of aspirate via Taqman array card (n = 60) was assessed in only cases. Giardia was the most frequent pathogen and was associated with raised L:R ratio (p = 0.068). Gastric microscopy was more sensitive than duodenal aspirate in H. pylori detection. Microscopically confirmed H. pylori negatively correlated with HAZ at 24 months (r = −0.313, p = 0.013). Regarding histopathological parameters, goblet cell reduction significantly correlated with decline in dual sugar excretion (p< 0.05). Between cases and controls, there were no significant differences in the median (25^th, 75^th percentile) of urinary concentrations (μg/ml) of lactulose [27.0 (11.50, 59.50) for cases vs. 38.0 (12.0, 61.0) for controls], rhamnose [66.0 (28.0, 178.0) vs. 86.5 (29.5, 190.5)] and L:R ratio [0.47 (0.24, 0.90) vs. 0.51 (0.31, 0.71)] respectively. In multivariable regression model, 31% of variability in HAZ at 24 months of age among cases and controls was explained by final model including dual sugars. In conclusion, enteropathogen burden is associated with altered histopathological features and intestinal permeability. In cases and controls living in settings of endemic enteropathy, intestinal permeability test may predict linear growth. However, for adoption as a screening tool for EED, further validation is required due to its complex intestinal pathophysiology.     

Over-expression of angiotensin II type 2 receptor (agtr2) decreases collagen accumulation in atherosclerotic plaque

Angiotensin (Ang) II, via type 1 receptor activation, exerts a significant role in atherogenesis and collagen synthesis. To test the hypothesis that Ang II type 2 receptor (AT2R) upregulation delivered with adeno-associated virus type 2 (AAV/AT2R) would inhibit collagen synthesis in atherosclerotic arteries, LDLR knockout mice were injected with AAV/AT2R and fed 4% cholesterol diet for 18 weeks. LDLR knockout mice treated with saline or AAV/Neo exhibited extensive vessel wall collagen accumulation, which was reduced by about 50% with AT2R over-expression. AT2R upregulation completely blocked the alterations in the expression of procollagen-I, osteopontin, fibronectin, CD68, and matrix metalloproteinases (MMP-2 and MMP-9), as well as phosphorylation of p38 and p44/42 MAPKs. Activity of superoxide dismutase was reduced in the LDLR KO mice and it increased with AT2R upregulation. This study demonstrates that AT2R over-expression reduces enhanced collagen accumulation, MMP expression and activity in atherosclerotic regions via inhibition of pro-oxidant signals.     

Fabry disease: twenty novel alpha-galactosidase A mutations and genotype-phenotype correlations in classical and variant phenotypes

BACKGROUND: Fabry disease (OMIM 301500) is an X-linked inborn error of glycosphingolipid metabolism resulting from mutations in the alpha-galactosidase A (alpha-Gal A) gene. The disease is phenotypically heterogeneous with classic and variant phenotypes. To assess the molecular heterogeneity, define genotype/phenotype correlations, and for precise carrier identification, the nature of the molecular lesions in the alpha-Gal A gene was determined in 40 unrelated families with Fabry disease. MATERIALS AND METHODS: Genomic DNA was isolated from affected males or obligate carrier females and the entire alpha-Gal A coding region and flanking sequences were amplified by PCR and analyzed by automated sequencing. Haplotype analyses were performed with polymorphisms within and flanking the alpha-Gal A gene. RESULTS: Twenty new mutations were identified (G43R, R49G, M72I, G138E, W236X, L243F, W245X, S247C, D266E, W287C, S297C, N355K, E358G, P409S, g1237del15, g10274insG, g10679insG, g10702delA, g11018insA, g11185-delT), each in a single family. In the remaining 20 Fabry families, 18 previously reported mutations were detected (R49P, D92N, C94Y, R112C [two families], F113S, W162X, G183D, R220X, R227X, R227Q, Q250X, R301X, R301Q, G328R, R342Q, E358K, P409A, g10208delAA [two families]). Haplotype analyses indicated that the families with the R112C or g10208delAA mutations were not related. The proband with the D266E lesion had a severe classic phenotype, having developed renal failure at 15 years. In contrast, the patient with the S247C mutation had a variant phenotype, lacking the classic manifestations and having mild renal involvement at 64 years. CONCLUSIONS: These results further define the heterogeneity of alpha-Gal A mutations causing Fabry disease, permit precise heterozygote detection and prenatal diagnosis in these families, and provide additional genotype/phenotype correlations in this lysosomal storage disease.     

A lysosomal pepstatin-insensitive proteinase as a novel biomarker for breast carcinoma

Lysosomal proteinases play an important role in the turnover of intracellular proteins, and acidic proteinases such as cathepsin D are known to be increased in breast carcinoma. In the present study the activity of a newly discovered acidic lysosomal pepstatin-insensitive proteinase (CLN2p) was measured in breast tissues by the most sensitive and highly specific assay that we had developed for the diagnosis of late-infantile neuronal ceroid lipofuscinosis (LINCL) (2). Samples from eight normal subjects undergoing reductive mammoplasty and 200 patients with primary breast carcinoma were analyzed. The results suggest a two- to seventeen-fold higher CLN2p activity in tumors, which was significantly and positively correlated with already known breast cancer biomarkers such as levels of cathepsin D, estrogen receptor and progesterone receptor. These results suggest a diagnostic and prognostic potential for this novel acid proteinase in breast cancer.     

Hydrothermal growth of Zn2SnO4:Eu,Ca for red emission

Zinc stannate (Zn₂SnO₄) and Zn₂SnO₄ codoped with Eu³⁺ and Ca²⁺ (ZTO:Eu,Ca) were synthesized by hydrothermal method and characterized with X‐ray diffraction (XRD), energy‐dispersive X‐ray analysis (EDAX), Raman spectrometer, field emission scanning electron microscopy (FESEM), ultraviolet‐visible (UV‐vis) and photoluminescence (PL) spectrophotometers. PL analysis of Zn₂SnO₄ gives broad defect induced emission in the region 500–750 nm. The crystal structure of Zn₂SnO₄ was retained even with a nominal doping of Eu, Ca and its combination in the Zn₂SnO₄. The Eu³⁺ ions were found to occupy the non‐centrosymmetric sites of the Zn₂SnO₄ and gave emissions at 592, 615 and 702 nm. Zn₂SnO₄:Eu,Ca showed red emission at 615 nm attributed to the electronic transition from the excited state ⁵D₀ → ⁷F₂ of the 4f⁶ configuration of Eu³⁺. Nominal codoping of Eu³⁺ and Ca²⁺ ions promoted the quenching of orange emission from Eu³⁺ in Zn₂SnO₄:Eu,Ca.     

Immunomodulation of dual specificity phosphatase 4 during visceral leishmaniasis

DUSP4, an inducible protein has a substrate specificity toward ERK1/2, a component of MAP kinase which is enhanced during Leishmania infection. The DUSP4^?/? mice show increased susceptibility towards the infection caused by Toxoplasma gondii and Leishmania mexicana. These observations emphatically established the fact that unlike DUSP1, DUSP4 has host protective role. In our study, it has been Leishmania donovani, the causative agent of visceral leishmaniasis (VL) significantly reduced the expression of DUSP4 during infection. In order to find out the host protective role of DUSP4 in macrophages during VL, we silenced DUSP4 prior to infection and the parasite number within macrophage was counted. Under DUSP4 knock-down condition, phosphorylation of p38 MAPK and generation of pro-inflammatory response like IL-12, TNF-α, and iNOS was decreased significantly. Silencing DUSP4 promoted the phosphorylation of ERK1/2 and the generation of anti-inflammatory response like- IL-10, TGF-β with increased Arginase-1 and Cox-2 activity. Glycyrrhizic Acid (GA), an immunomodulator, already known to suppress L. donovani infection, found to up-regulate DUSP4 expression during L. donovani infection. On the other hand, GA failed to increase Th1 cytokine production and decrease Th2 response during DUSP4 knock-down condition suggesting the key role of DUSP4 while providing protection during L. donovani infection.