Cardiomyocyte Ca2+ handling and structure is regulated by degree and duration of mechanical load variation

Cardiac transverse (t)‐tubules are altered during disease and may be regulated by stretch‐sensitive molecules. The relationship between variations in the degree and duration of load and t‐tubule structure remains unknown, as well as its implications for local Ca²⁺‐induced Ca²⁺ release (CICR). Rat hearts were studied after 4 or 8 weeks of moderate mechanical unloading [using heterotopic abdominal heart–lung transplantation (HAHLT)] and 6 or 10 weeks of pressure overloading using thoracic aortic constriction. CICR, cell and t‐tubule structure were assessed using confocal‐microscopy, patch‐clamping and scanning ion conductance microscopy. Moderate unloading was compared with severe unloading [using heart‐only transplantation (HAHT)]. Mechanical unloading reduced cardiomyocyte volume in a time‐dependent manner. Ca²⁺ release synchronicity was reduced at 8 weeks moderate unloading only. Ca²⁺ sparks increased in frequency and duration at 8 weeks of moderate unloading, which also induced t‐tubule disorganization. Overloading increased cardiomyocyte volume and disrupted t‐tubule morphology at 10 weeks but not 6 weeks. Moderate mechanical unloading for 4 weeks had milder effects compared with severe mechanical unloading (37% reduction in cell volume at 4 weeks compared to 56% reduction after severe mechanical unloading) and did not cause depression and delay of the Ca²⁺ transient, increased Ca²⁺ spark frequency or impaired t‐tubule and cell surface structure. These data suggest that variations in chronic mechanical load influence local CICR and t‐tubule structure in a time‐ and degree‐dependent manner, and that physiological states of increased and reduced cell size, without pathological changes are possible.     

Tomato powder impedes the development of azoxymethane-induced colorectal cancer in rats through suppression of COX-2 expression via NF-κB and regulating Nrf2/HO-1 pathway

Cancer is one of the leading causes of death worldwide. Since dietary factors have been connected to a reduced risk of a diversity of human cancers, in this study we investigated the effects of tomato powder (TP) on the development of azoxymethane (AOM)-induced colorectal cancer in Wistar rats, and possible mechanism(s) by which TP shows its chemopreventive activity. Here we show that TP added to feed at 5% rate decreases the rate of aberrant crypt foci (ACF) and reduces the development of adenocarcinoma and growth of AOM-induced colorectal cancer in rats. In addition, we demonstrate that TP supplementation shows its chemopreventive activities through inhibition of cyclooxygenase-2 (COX-2) expression via NF-κB pathway and promotion of apoptosis, as well as regulating Nrf2/HO-1 signaling pathway in colorectal tissue of AOM-treated rats. Our findings identify an intimate connection between dietary supplementation of TP and the decreased risk of colorectal cancer in rats, and suggest that consumption of TP would be a natural candidate for the prevention of colorectal cancer in men.     

Biological Assessment of Water Pollution Using Periphyton Productivity and Standing Crop in the Linggi River,Malaysia

Many assessments of water pollution in aquatic ecosystem have focused mainly on physical and chemical characteristics. However, until recently, biological aspects have been given little attention. Although physical and chemical methods of assessing water pollution are relatively simple to interpret, biological assessments have many strong merits. Therefore an attempt was made to use periphyton productivity (in terms of biomass ash‐free dry weight, AFDW) and chlorophyll‐a content (measured from periphyton colonized on glass microscope slides) to assess water pollution in the Linggi river. The Linggi River is a tropical lotic system in the country of Malaysia. As a result of increased nutrient enrichment due to sewage and agro‐industrial wastes, analyses of accumulated periphyton on glass slides showed increased biomass AFDW from an unpolluted upstream reach to the highly polluted downstream reach of the river. In contrast to biomass, the chlorophyll‐a content of the accumulated periphyton was not always directly related to the AFDW of the biomass. Though the highly polluted Station 4 showed high biomass AFDW and chlorophyll‐a, due to increased nutrient enrichment. The chlorophyll‐a values at slightly polluted Station 2 were lower than at the unpolluted Station 1. Meanwhile, the mean chlorophyll‐a content observed in Linggi river was relatively high as compared to previous studies carried out in Malaysia. When the Water Quality Index (WQI) was calculated using key chemical parameters linked to organic pollution, there was a significant correlation between chemical parameters, biomass AFDW, and chorophyll‐a. Though the chlorophyll‐a content increased with decreases in the WQI, similar to the biomass AFDW, the chlorophyll‐a values were found to be lower in slightly polluted Station 2 than unpolluted Station 1. Therefore it was not necessary that an increase in the biomass AFDW, due to nutrient enrichment, would always increase the chlorophyll‐a in accumulated periphyton (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,potential antitumor activity,cell cycle analysis,and multitarget mechanisms of novel hydrazones incorporating a 4-methylsulfonylbenzene scaffold: a molecular docking study

Hydrazone is a bioactive pharmacophore that can be used to design antitumor agents. We synthesised a series of hydrazones (compounds 4–24) incorporating a 4-methylsulfonylbenzene scaffold and analysed their potential antitumor activity. Compounds 6, 9, 16, and 20 had the most antitumor activity with a positive cytotoxic effect (PCE) of 52/59, 27/59, 59/59, and 59/59, respectively, while compounds 5, 10, 14, 15, 18, and 19 had a moderate antitumor activity with a PCE of 11/59–14/59. Compound 20 was the most active and had a mean 50% cell growth inhibition (GI₅₀) of 0.26 µM. Compounds 9 and 20 showed the highest inhibitory activity against COX-2, with a half-maximal inhibitory concentration (IC₅₀) of 2.97 and 6.94 μM, respectively. Compounds 16 and 20 significantly inhibited EGFR (IC₅₀ = 0.2 and 0.19 μM, respectively) and HER2 (IC₅₀ = 0.13 and 0.07 μM, respectively). Molecular docking studies of derivatives 9, 16, and 20 into the binding sites of COX-2, EGFR, and HER2 were carried out to explore the interaction mode and the structural requirements for antitumor activity.     

Aniseed oil increases glucose absorption and reduces urine output in the rat

Anise (Pimpinella anisum) has been used as a traditional aromatic herb in many drinks and baked foods because of the presence of volatile oils in its fruits commonly known as seeds. Hot water extracts of the seeds have been used also in folk medicine for their diuretic and laxative effect, expectorant and anti-spasmodic action, and their ability to ease intestinal colic and flatulence. The aim of this work was to study the effect of aniseed oil on transport processes through intestinal and renal epithelia and determine its mechanism of action. The essential oils were extracted from the seeds by hydrodistillation and analyzed by gas chromatography. Aniseed oil enhanced significantly glucose absorption from the rat jejunum and increased the Na+-K+ ATPase activity in a jejunal homogenate in a dose dependent manner. The oil, however, exerted no effect on water absorption from the colon and did not alter the activity of the colonic Na+-K+ ATPase. When added to drinking water, it reduced the volume of urine produced in the rat and increased the activity of the renal Na+-K+ ATPase even at extremely low concentrations. It was concluded that aniseed oil increases glucose absorption by increasing the activity of the Na+-K+ ATPase and consequently the sodium gradient needed for the sugar transport. Its anti-diuretic effect is also mediated through a similar mechanism in the kidney whereby a stimulation of the Na+-K+ pump increases tubular sodium reabsorption and osmotic water movement. The colonic Na+-K+ ATPase was however, resistant to the oil.     

Expanding the repertoire of electron acceptors for the anaerobic oxidation of methane in carbonates in the Atlantic and Pacific Ocean

Authigenic carbonates represent a significant microbial sink for methane, yet little is known about the microbiome responsible for the methane removal. We identify carbonate microbiomes distributed over 21 locations hosted by seven different cold seeps in the Pacific and Atlantic Oceans by carrying out a gene-based survey using 16S rRNA- and mcrA gene sequencing coupled with metagenomic analyses. Based on 16S rRNA gene amplicon analyses, these sites were dominated by bacteria affiliated to the Firmicutes, Alpha- and Gammaproteobacteria. ANME-1 and -2 archaeal clades were abundant in the carbonates yet their typical syntrophic partners, sulfate-reducing bacteria, were not significantly present. Based on mcrA amplicon analyses, the Candidatus Methanoperedens clades were also highly abundant. Our metagenome analysis indicated that methane oxidizers affiliated to the ANME-1 and -2, may be capable of performing complete methane- and potentially short-chain alkane oxidation independently using oxidized sulfur and nitrogen compounds as terminal electron acceptors. Gammaproteobacteria are hypothetically capable of utilizing oxidized nitrogen compounds and may be involved in syntrophy with methane-oxidizing archaea. Carbonate structures represent a window for a more diverse utilization of electron acceptors for anaerobic methane oxidation along the Atlantic and Pacific Margin.Subject terms: Microbiology, Biogeochemistry     

Melatonin is a potent inhibitor for myeloperoxidase

Myeloperoxidase (MPO) catalyzes the formation of potent oxidants that have been implicated in the pathogenesis of various diseases including atherosclerosis, asthma, arthritis, and cancer. Melatonin plays an important part in the regulation of various body functions including circadian sleep rhythms, blood pressure, oncogenesis, retinal function, seasonal reproduction, and immunity. Here, we demonstrate that melatonin serves as a potent inhibitor of MPO under physiological-like conditions. In the presence of chloride (Cl-), melatonin inactivated MPO at two points in the classic peroxidase cycle through binding to MPO to form an inactive complex, melatonin-MPO-Cl, and accelerating MPO compound II formation, an inactive form of MPO. Inactivation of MPO was mirrored by the direct conversion of MPO-Fe(III) to MPO compound II without any sign of compound I accumulation. This behavior indicates that melatonin binding modulates the formation of MPO intermediates and their decay rates. The Cl- presence enhanced the affinity of MPO toward melatonin, which switches the enzyme activity from peroxidation to catalase-like activity. In the absence of Cl-, melatonin served as a 1e- substrate for MPO compound I, but at higher concentration it limited the reaction by its dissociation from the corresponding complex. Importantly, melatonin-dependent inhibition of MPO occurred with a wide range of concentrations that span various physiological and supplemental ranges. Thus, the interplay between MPO and melatonin may have a broader implication in the function of several biological systems. This dual regulation by melatonin is unique and represents a new means through which melatonin can control MPO and its downstream inflammatory pathways.     

DFT analysis of axial and equatorial effects on heme-CO vibrational modes: applications to CooA and H-NOX heme sensor proteins

Determinants of the Fe-CO and C-O stretching frequencies in (imidazole)heme-CO adducts have been investigated via density functional theory (DFT) analysis, in connection with puzzling characteristics of the heme sensor protein CooA and of the H-NOX (Heme-Nitric Oxide and/or OXygen binding) family of proteins, including soluble guanylate cyclase (sGC). The computations show that two mechanisms of Fe-histidine bond weakening have opposite effects on the nuFeC/nuCO pattern. Mechanical tension is expected to raise nuFeC with little change in nuCO whereas the weakening of H-bond donation from the imidazole ligand has the opposite effect. Data on CooA indicate imidazole H-bond weakening associated with heme displacement, as part of the activation mechanism. The computations also reveal that protein-induced distortion of the porphyrin ring, a prominent structural feature of the H-NOX protein TtTar4H (Thermoanaerobacter tengcongensis Tar4 protein heme domain), has surprisingly little effect on nuFeC or nuCO. However, another structural feature, strong H-bonding to the propionates, is suggested to account for the weakened back bonding that is evident in sGC. TtTar4H-CO itself has an elevated nuFeC, which is successfully modeled as a compression effect, resulting from steric crowding in the distal pocket. nuFeC/nuCO data, in conjunction with modeling, can provide valuable insight into mechanisms for heme-protein modulation.