Resonance energy transfer nanobiosensors based on affinity binding between apo-enzyme and its substrate

Systems for glucose monitoring based on resonance energy transfer (RET) and competitive binding using Concanavalin A (Con A) are problematic as a result of problems of toxicity, aggregation, and irreversible binding. This paper presents an improved RET assay wherein Con A was replaced by apo-glucose oxidase (apo-GOx). The basic principle for transduction is identical to that used in assays based on Con A-dextran: a reduction in RET from fluorescein isothiocyanate (FITC) to tetramethyl rhodamine isothiocyanate (TRITC) occurs when FITC-dextran (donor) is displaced from TRITC-apo-GOx (acceptor) as a result of the competition of glucose. Fluorescence measurements confirm that the apo-GOx/dextran complexes are highly sensitive to glucose, measured as an increase in the donor peak relative to acceptor due to stepwise addition of glucose. The solution-phase assay showed strong signals and excellent repeatability, with a sensitivity of 0.0163 (ratio units)/mM over the range of 0-90 mM glucose. If properly encapsulated, these sensors can potentially be used for in vivo sensing without the concern of toxicity associated with Con A.     

Unveiling hidden catalytic contributions of the conserved His/Trp-III in tyrosine recombinases: assembly of a novel active site in Flp recombinase harboring alanine at this position

The catalytic pentad of tyrosine recombinases, that assists the tyrosine nucleophile, includes a conserved histidine/tryptophan (His/Trp-III). Flp and Cre harbor tryptophan at this position; most of their kin recombinases display histidine. Contrary to the conservation rule, Flp(W330F) is a much stronger recombinase than Flp(W330H). The hydrophobicity of Trp330 or Phe330 is utilized in correctly positioning Tyr343 during the strand cleavage step of recombination. Why then is phenylalanine almost never encountered in the recombinase family at this conserved position? Using exogenous nucleophiles and synthetic methylphosphonate or 5'-thiolate substrates, we decipher that Trp330 also assists in the activation of the scissile phosphate and the departure of the 5'-hydroxyl leaving group. These two functions are consistent with the hydrogen bonding property of Trp330 as well as its location in structures of the Flp recombination complexes. However, van der Waals contact between Trp330 and Arg308 may also be important for the phosphate activation step. A structure based suppression strategy permits the inactive variant Flp(W330A) to be rescued by a second site mutation A339M. Modeling alanine and methionine at positions 330 and 339, respectively, in the Flp crystal structure suggests a plausible mechanism for active site restoration. Successful suppression suggests the possibility of evolving, by design, new active site configurations for tyrosine recombination.     

Role of Periodontal Bacteria,Viruses, and Placental mir155 in Chronic Periodontitis and Preeclampsia—A Genetic Microbiological Study

Previous studies assessed the involvement and impact of periodontal bacteria in preeclamptic women with chronic periodontitis. To explore further, the current study aimed to associate periodontal viruses and bacteria with mir155 levels in placental tissues of preeclamptic women with generalized chronic periodontitis. Four-hundred 45 pregnant women, 18–35 years of age, were selected and divided into four groups (controls, A, B, and C) where the Controls included 145 systemically and periodontally healthy pregnant women Group A-100 systemically healthy pregnant women with chronic periodontitis, Group B- 100 preeclamptic women with chronic periodontitis, Group C- 100 preeclamptic women without chronic periodontitis. Age, BMI, SES, and periodontal parameters such as PI, BOP, PPD, and CAL were noted. Periodontal pathogens such as Tf, Td, Pg, Pi, Fn, HSV, EBV, and HCMV were tested in subgingival plaque, placental tissues, and mir155. We observed that PI, BOP, PPD, CAL, Tf, and EBV were highly significant in Group B. We found a higher number of periodontal bacteria, viruses, and mir 155 in Group B showing a higher risk of preeclampsia. More genetic studies in this field are advised to ascertain the role of periodontopathogens and mir 155 in preeclampsia and periodontal inflammation. What is already known on this subject? Periodontal diseases pose an increased risk of developing preeclampsia and delivering preterm and/or low-birth-weight babies. What do the results of this study add? Periodontal variables such as PI, pocket depth, BOP, and clinical attachment levels, were found to be increased in the preeclamptic women with chronic periodontitis. The significant difference was seen in the relative fold expression of mir155 with higher gene expression of mir155 in groups B and A as compared to group C and controls. What are the implications of these findings for clinical practice and/or further research? In our study, mir155 correlation with the periodontal parameters and periodontal pathogens further strengthen the evidence of periodontal inflammation as a risk of preeclampsia in pregnant women especially when associated with chronic periodontitis. mir155 can be considered to be one of the genetic biomarkers and can be used as a diagnostic tool for the early detection of PE.     

Feline tetherin efficiently restricts release of feline immunodeficiency virus but not spreading of infection

Domestic cats endure infections by all three subfamilies of the retroviridae: lentiviruses (feline immunodeficiency virus [FIV]), gammaretroviruses (feline leukemia virus [FeLV]), and spumaretroviruses (feline foamy virus [FFV]). Thus, cats present an insight into the evolution of the host-retrovirus relationship and the development of intrinsic/innate immune mechanisms. Tetherin (BST-2) is an interferon-inducible transmembrane protein that inhibits the release of enveloped viruses from infected cells. Here, we characterize the feline homologue of tetherin and assess its effects on the replication of FIV. Tetherin was expressed in many feline cell lines, and expression was induced by interferons, including alpha interferon (IFN-α), IFN-ω, and IFN-γ. Like human tetherin, feline tetherin displayed potent inhibition of FIV and HIV-1 particle release; however, this activity resisted antagonism by either HIV-1 Vpu or the FIV Env and "OrfA" proteins. Further, as overexpression of complete FIV genomes in trans could not overcome feline tetherin, these data suggest that FIV lacks a functional tetherin antagonist. However, when expressed stably in feline cell lines, tetherin did not abrogate the replication of FIV; indeed, syncytium formation was significantly enhanced in tetherin-expressing cells infected with cell culture-adapted (CD134-independent) strains of FIV (FIV Fca-F14 and FIV Pco-CoLV). Thus, while tetherin may prevent the release of nascent viral particles, cell-to-cell spread remains efficient in the presence of abundant viral receptors and tetherin upregulation may enhance syncytium formation. Accordingly, tetherin expression in vivo may promote the selective expansion of viral variants capable of more efficient cell-to-cell spread.     

Clinically-Relevant Cutaneous Lesions by Nitrogen Mustard: Useful Biomarkers of Vesicants Skin Injury in SKH-1 Hairless and C57BL/6 Mice

A paucity of clinically applicable biomarkers to screen therapies in laboratory is a limitation in the development of countermeasures against cutaneous injuries by chemical weapon, sulfur mustard (SM), and its analog nitrogen mustard (NM). Consequently, we assessed NM-caused progression of clinical cutaneous lesions; notably, skin injury with NM is comparable to SM. Exposure of SKH-1 hairless and C57BL/6 (haired) mice to NM (3.2 mg) for 12–120 h caused clinical sequelae of toxicity, including microblister formation, edema, erythema, altered pigmentation, wounding, xerosis and scaly dry skin. These toxic effects of NM were similar in both mouse strains, except that wounding and altered pigmentation at 12–24 h and appearance of dry skin at 24 and 72 h post-NM exposure were more pronounced in C57BL/6 compared to SKH-1 mice. Conversely, edema, erythema and microblister formation were more prominent in SKH-1 than C57BL/6 mice at 24–72 h after NM exposure. In addition, 40–60% mortality was observed following 120 h of NM exposure in the both mouse strains. Overall, these toxic effects of NM are comparable to those reported in humans and other animal species with SM, and thus represent clinically-relevant cutaneous injury endpoints in screening and optimization of therapies for skin injuries by vesicating agents.     

Mechanisms of sulfur mustard analog 2-chloroethyl ethyl sulfide-induced DNA damage in skin epidermal cells and fibroblasts

Employing mouse skin epidermal JB6 cells and dermal fibroblasts, here we examined the mechanisms of DNA damage by 2-chloroethyl ethyl sulfide (CEES), a monofunctional analog of sulfur mustard (SM). CEES exposure caused H2A.X and p53 phosphorylation as well as p53 accumulation in both cell types, starting at 1 h, that was sustained for 24 h, indicating a DNA-damaging effect of CEES, which was also confirmed and quantified by alkaline comet assay. CEES exposure also induced oxidative stress and oxidative DNA damage in both cell types, measured by an increase in mitochondrial and cellular reactive oxygen species and 8-hydroxydeoxyguanosine levels, respectively. In the studies distinguishing between oxidative and direct DNA damage, 1 h pretreatment with glutathione (GSH) or the antioxidant Trolox showed a decrease in CEES-induced oxidative stress and oxidative DNA damage. However, only GSH pretreatment decreased CEES-induced total DNA damage measured by comet assay, H2A.X and p53 phosphorylation, and total p53 levels. This was possibly due to the formation of GSH–CEES conjugates detected by LC-MS analysis. Together, our results show that CEES causes both direct and oxidative DNA damage, suggesting that to rescue SM-caused skin injuries, pleiotropic agents (or cocktails) are needed that could target multiple pathways of mustard skin toxicities.     

Synthesis of various 3-nitropropionamides as Mycobacterium tuberculosis isocitrate lyase inhibitor

Various 3-nitropropionamides were synthesized and evaluated for in vitro activities against log and starved phase culture of two mycobacterial species and Mycobacterium tuberculosis (MTB) isocitrate lyase (ICL) enzyme inhibition studies. Among 22 compounds, 1-cyclopropyl-7-(3,5-dimethyl-4-(3-nitropropanoyl)piperazin-1-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (22) was found to be the most active compound in vitro with MICs of 0.16 and 0.04 μM against log- and starved-phase culture of MTB. Compound 22 also showed good enzyme inhibition of MTB ICL with IC(50) of 0.10 ± 0.01 μM. The docking studies also confirmed the binding potential of the compounds at the ICL active site.     

Structure-activity relationship studies of novel pyrazole and imidazole carboxamides as cannabinoid-1 (CB1) antagonists

The synthesis and biological evaluation of novel pyrazole and imidazole carboxamides as CB1 antagonists are described. As a part of eastern amide SAR, various chemically diverse motifs were introduced on rimonabant template. The central pyrazole core was also replaced with its conformationally constrained motif and imidazole moieties. In general, a range of modifications were well tolerated. Several molecules with low- and sub-nanomolar potencies were identified as potent CB1 receptor antagonists. The in vivo proof of principle for weight loss is demonstrated with a lead compound in DIO mice model.