The inhibition by naphthoquinones and anthraquinones of 2-amino-3-methylimidazo[4,5-f?]quinoline metabolic activation to a mutagen: a structure-activity relationship study

 Nine naphthoquinones, 19 anthraquinones, and nine structurally related monoketonic compounds such as anthrone, xanthone, etc., inhibited mutagenicity induced by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in Salmonella typhimurium TA 98 in the presence of rat liver S9 with distinct structure-activity relationships. A carbonyl function was a prerequisite for antimutagenicity while, in general, anthraquinones (IC₅₀ values: 2.3–>213 nmol/ml top agar) were more potent antimutagens than structurally related monoketonic compounds (IC₅₀ values: 25.3–94.9 nmol/ml top agar) and naphthoquinones (IC₅₀ values: 3.7–90.7 nmol/ml top agar). The parent compounds and methyl substituted derivatives were already the most potent while introduction of polar substituents such as COOH and SO₃H considerably reduced antimutagenicity. Introduction of OH functions had equivocal effects: with increasing numbers, antimutagenic potencies were concomitantly reduced; however, anthraflavic acid, chrysazin, quinizarin, and especially 5,8-dihydroxy-1,4-naphthoquinone were more potent than the parent compounds. The patterns of inhibition by quinones of 7-ethoxyresorufin-O-dealkylase activities in rat liver microsomes, linked to cytochrome P-450-dependent oxidation of IQ to N-hydroxy-IQ (N-OH-IQ), were in general identical with those obtained in the Salmonella/reversion assay except for chrysophanic acid, emodin, and some naphthoquinones which were very potent in this assay (IC₅₀: 0.20–45.0 μM). On the other hand, mutagenicity of N-OH-IQ in S. typhimurium TA 98NR was not inhibited by nonpolar quinones (except 1,4-naphthoquinone) but rather by polar compounds and especially by hydroxyquinones (IC₅₀ values: 5.3–106.7 nmol/ml top agar or not reached). Inhibition of mutagenic activities of IQ, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-6-methyldipyrido[1,2-a:3′,2′-d]imidazole, and 3-amino-1-methyl-5H-pyrido[4,3-b]indole by chrysazin, chrysophanic acid, physicon, and purpurin varied, but no clearcut structure-activity relationships of the mutagens were observed. Received: 29 May 1998     

Objective measurement of tactile mislocalization

Stimulating the skin with intensities close to the sensory threshold causes erroneous localization of the site of stimulation. Previous studies using manual methods for applying faint tactile stimuli have shown that localization errors obey a somatotopic principle in which tactile stimuli are preferentially mislocalized to sites adjacent to the stimulated skin region. However, manual testing of mislocalization is time consuming and only partially objective because results depend on the skills of the tester. To improve the testing procedure, an automated apparatus was developed. The procedure adjusted stimulus intensity adaptively during testing to remain near the individual subject's sensory threshold, so that mislocalizations occurred often enough to assess somatotopic organization. The new method was applied to 12 healthy subjects. In each subject, the five digits of the right hand were stimulated singly in random order. Localization errors were distributed preferentially to fingers close to the stimulated finger rather than to distant fingers. The profile of mislocalization differed significantly from that expected on the basis of response bias or guessing behavior. The present results replicate previous findings obtained for manual testing with improved sensitivity and indicate that the new technique is a useful tool for the study of somatosensory processing on a perceptual level.     

Engineered Lipid Nanoparticles for the Treatment of Pulmonary Fibrosis by Regulating Epithelial-Mesenchymal Transition in the Lungs

Pulmonary fibrosis is a chronic and irreversible lung disease with limited therapeutic regimens. Advances in elucidating the pathophysiological mechanism and discovering novel therapeutic interventions are still in urgent need. Here, the engineered lipid nanoparticles (LNPs) are developed for delivering RNA therapeutics to the lungs. Three different types of LNPs (native, cationic, and ligand incorporated) are optimized to facilitate the pulmonary delivery of RNAs. Among them, the mannose incorporated LNPs (Mannose LNPs) outperform the others and show efficient delivery of siRNAs down-regulating the epithelial-mesenchymal transition (EMT) associated protein, G2 and S phase-expressed protein 1 (GTSE1). Treatment with the mannose LNPs confirms a significant decrease in collagen accumulation and EMT-related proteins in the fibrosis animal models and provides functional recovery from pulmonary fibrosis. This approach demonstrates that engineered LNPs can facilitate the delivery of RNA therapeutics to the lungs and potentially open a new regimen of treatment for pulmonary fibrosis.     

The Newly Sequenced Genome of Pisum sativum Is Replete with Potential G-Quadruplex-Forming Sequences—Implications for Evolution and Biological Regulation

G-quadruplexes (G4s) have been long considered rare and physiologically unimportant in vitro curiosities, but recent methodological advances have proved their presence and functions in vivo. Moreover, in addition to their functional relevance in bacteria and animals, including humans, their importance has been recently demonstrated in evolutionarily distinct plant species. In this study, we analyzed the genome of Pisum sativum (garden pea, or the so-called green pea), a unique member of the Fabaceae family. Our results showed that this genome contained putative G4 sequences (PQSs). Interestingly, these PQSs were located nonrandomly in the nuclear genome. We also found PQSs in mitochondrial (mt) and chloroplast (cp) DNA, and we experimentally confirmed G4 formation for sequences found in these two organelles. The frequency of PQSs for nuclear DNA was 0.42 PQSs per thousand base pairs (kbp), in the same range as for cpDNA (0.53/kbp), but significantly lower than what was found for mitochondrial DNA (1.58/kbp). In the nuclear genome, PQSs were mainly associated with regulatory regions, including 5′UTRs, and upstream of the rRNA region. In contrast to genomic DNA, PQSs were located around RNA genes in cpDNA and mtDNA. Interestingly, PQSs were also associated with specific transposable elements such as TIR and LTR and around them, pointing to their role in their spreading in nuclear DNA. The nonrandom localization of PQSs uncovered their evolutionary and functional significance in the Pisum sativum genome.     

Empagliflozin Treatment Attenuates Hepatic Steatosis by Promoting White Adipose Expansion in Obese TallyHo Mice

Sodium-glucose co-transporters (SGLTs) serve to reabsorb glucose in the kidney. Recently, these transporters, mainly SGLT2, have emerged as new therapeutic targets for patients with diabetes and kidney disease; by inhibiting glucose reabsorption, they promote glycosuria, weight loss, and improve glucose tolerance. They have also been linked to cardiac protection and mitigation of liver injury. However, to date, the mechanism(s) by which SGLT2 inhibition promotes systemic improvements is not fully appreciated. Using an obese TallyHo mouse model which recapitulates the human condition of diabetes and nonalcoholic fatty liver disease (NAFLD), we sought to determine how modulation of renal glucose handling impacts liver structure and function. Apart from an attenuation of hyperglycemia, Empagliflozin was found to decrease circulating triglycerides and lipid accumulation in the liver in male TallyHo mice. This correlated with lowered hepatic cholesterol esters. Using in vivo MRI analysis, we further determined that the reduction in hepatic steatosis in male TallyHo mice was associated with an increase in nuchal white fat indicative of “healthy adipose expansion”. Notably, this whitening of the adipose came at the expense of brown adipose tissue. Collectively, these data indicate that the modulation of renal glucose handling has systemic effects and may be useful as a treatment option for NAFLD and steatohepatitis.     

The Potential of Confocal Imaging for Measuring Physiological Changes in Brewer's Yeast

This study focused on the implementation of fluorescence optical methods and laser scanning confocal microscopy for monitoring brewing yeast performance. Physiological parameters and cell compounds in yeast cells (glycogen, neutral lipids, trehalose, bud scars, DNA and intracellular proteinases) have been successfully visualised with the aid of highly specific fluorochromes. The expression and sub cellular localisation of proteinase A during fermentation has been studied employing a Saccharomyces cerevisiae green fluorescent protein clone. This novel approach to monitoring brewing yeast performance provides new insights into physiological events that occur during wort fermentation.     

In Situ Ultrasonic Characterization of Cocoa Butter Using a Chirp

Differences between tempered and untempered cocoa butter were investigated by an ultrasonic signal “chirp” generated by contact transducers. Polarized light microscopy and powder X-ray diffraction were used to characterize the morphology and polymorphism of tempered and untempered cocoa butter, whereas pulsed nuclear magnetic resonance was used to determine the amount of crystalline solids present. Ultrasonic wave velocity and attenuation data were collected simultaneously throughout the 5-h crystallization process for cocoa butter. Ultrasonic velocity and attenuation changed at the different solid fat contents (SFC): 4, 8, and 11 %. Untempered cocoa butter showed an attenuation of 3 dB/cm at 1.7 MHz and 4 % SFC, whereas tempered cocoa butter showed an attenuation of 4.5 dB/cm at 1.7 MHz and 4 % SFC. At 3 MHz, the attenuation was 2 dB/cm for untempered and 6 dB/cm for tempered cocoa butter. Under these conditions (4 % SFC, 3 MHz), the chirp wave of tempered sample showed a phase angle change of 0.5 rad, whereas the untempered sample showed ?0.5 rad relative to the canola oil that was taken as 0. The study suggests that an ultrasonic chirp can be effectively used to detect differences between tempered and untempered cocoa butter when measuring attenuation and ultrasonic wave phase angle changes as a function of frequency. The in-line characterization of chocolate “temper” using such nondestructive ultrasonic measurements could be applied to industrial chocolate manufacturing.     

Long-term residual effect of short-term fertilizer application on Ca,N and P concentrations in grasses <Emphasis Type="Italic">Nardus stricta</Emphasis> L. and <Emphasis Type="Italic">Avenella flexuosa</Emphasis> L.

The resilience (the ability of an ecosystem to recover after termination of perturbation) of plant species composition after short-term fertilizer application can take decades in sub-alpine grassland, but little attention has been paid to the resilience of nutrient concentrations in the biomass of individual plant species. In 2004, an abandoned experiment in which phosphorus, nitrogen and calcium had been applied from 1965 to 1967 was identified in the Giant Mts. (Krkonoše/Karkonosze, Czech Republic). The biomass of two dominant grasses, Nardus stricta and Avenella flexuosa, was analyzed for Ca, N and P concentrations 37 years after the last fertilizer application. In treatments with P application, the P concentration was still significantly increased in both species. The N concentration was higher in treatments with N or Ca application and the lowest in P treatments. The N:P ratio ranged from 7.7 to 16.6 and from 6.2 to 16.3 in N. stricta and A. flexuosa, respectively, and was lowest in P treatments where A. flexuosa predominated. N. stricta dominated in treatments where the biomass N:P ratio was higher than 13, whereas lower ratios were more favourable for A. flexuosa. In the case of N. stricta, the Ca concentration was increased in Ca treatments. Ca and P concentrations in N. stricta biomass were significantly positively correlated with soil plant available P and Ca concentrations, but this was not recorded for A. flexuosa. In environments with different P availability, the competitive ability of investigated species was predetermined by the N:P ratio in their biomass. As in the case of plant species composition and soil chemical properties, the resilience of Ca, N and P concentrations in the biomass of individual species can take decades in sub-alpine grassland.