Response of nitrifying bacterial communities to the increased thiocyanate concentration in pre-denitrification process

Changes in process performance and the nitrifying bacterial community associated with an increase of thiocyanate (SCN⁻) loading were investigated in a pre-denitrification process treating industrial wastewater. The increased SCN⁻ loading led to the concentration of total nitrogen (TN) in the final effluent, but increasing the internal recycling ratio as an operation parameter from 2 to 5 resulted in a 21% increase in TN removal efficiency. In the aerobic reactor, we found that the Nitrosomonas europaea lineage was the predominant ammonia oxidizing bacteria (AOB) and the percentages of the AOB population within the total bacteria increased from about 4.0% to 17% with increased SCN⁻ concentration. The increase of nitrite loading seemed to change the balance between Nitrospira and Nitrobacter, resulting in the high dominance of Nitrospira over Nitrobacter. Meanwhile, a Thiobacillus thioparus was suggested to be the main microorganism responsible for the SCN⁻ biodegradation observed in the system.     

Postconditioning for salvage of ischemic skeletal muscle from reperfusion injury: efficacy and mechanism

We tested our hypothesis that postischemic conditioning (PostC) is effective in salvage of ischemic skeletal muscle from reperfusion injury and the mechanism involves inhibition of opening of the mitochondrial permeability transition pore (mPTP). In bilateral 8x13 cm pig latissimus dorsi muscle flaps subjected to 4 h ischemia, muscle infarction increased from 22+/-4 to 41+/-1% between 2 and 24 h reperfusion and remained unchanged at 48 (38+/-6%) and 72 (40+/-1%) h reperfusion (P<0.05; n=4 pigs). PostC induced by four cycles of 30-s reperfusion/reocclusion at the onset of reperfusion after 4 h ischemia reduced muscle infarction from 44+/-2 to 22+/-2% at 48 h reperfusion. This infarct protective effect of PostC was mimicked by intravenous injection of the mPTP opening inhibitor cyclosporin A or NIM-811 (10 mg/kg) at 5 min before the end of 4 h ischemia and was abolished by intravenous injection of the mPTP opener atractyloside (10 mg/kg) at 5 min before PostC (P<0.05; n=4-5 pigs). PostC or intravenous cyclosporin A injection at 5 min before reperfusion caused a decrease in muscle myeloperoxidase activity and mitochondrial free Ca2+ concentration and an increase in muscle ATP content after 4 h ischemia and 2 h reperfusion compared with the time-matched controls. These effects of PostC were abolished by intravenous injection of atractyloside at 5 min before PostC (P<0.05; n=6 pigs). These observations support our hypothesis that PostC is effective in salvage of ischemic skeletal muscle from reperfusion injury and the mechanism involves inhibition of opening of the mPTP.     

CTCF cis-Regulates Trinucleotide Repeat Instability in an Epigenetic Manner: A Novel Basis for Mutational Hot Spot Determination

At least 25 inherited disorders in humans result from microsatellite repeat expansion. Dramatic variation in repeat instability occurs at different disease loci and between different tissues; however, cis-elements and trans-factors regulating the instability process remain undefined. Genomic fragments from the human spinocerebellar ataxia type 7 (SCA7) locus, containing a highly unstable CAG tract, were previously introduced into mice to localize cis-acting “instability elements,” and revealed that genomic context is required for repeat instability. The critical instability-inducing region contained binding sites for CTCF—a regulatory factor implicated in genomic imprinting, chromatin remodeling, and DNA conformation change. To evaluate the role of CTCF in repeat instability, we derived transgenic mice carrying SCA7 genomic fragments with CTCF binding-site mutations. We found that CTCF binding-site mutation promotes triplet repeat instability both in the germ line and in somatic tissues, and that CpG methylation of CTCF binding sites can further destabilize triplet repeat expansions. As CTCF binding sites are associated with a number of highly unstable repeat loci, our findings suggest a novel basis for demarcation and regulation of mutational hot spots and implicate CTCF in the modulation of genetic repeat instability.     

Screening of Korean herbal medicines used to improve cognitive function for anti-cholinesterase activity.

Methanolic extracts of seven herbs (Acorus calamus, Acorus gramineus, Bupleurm facaltum, Dioscorea batatas, Epimedium koreanum, Poria cocos and Zizyphi jujuba) used in traditional Korean medicine for improvement of memory and cognition in old age were tested for cholinesterase inhibitory properties using the Ellman colorimetric method. Significant inhibition of the enzyme at 200 microg/ml was observed for extracts from A. calamus and E. koreanum. The possible bases for the reputation of these and the other herbs tested are discussed in the light of previous investigations into their chemistry and biological activity.     

Two enzymes in one; two yeast peroxiredoxins display oxidative stress-dependent switching from a peroxidase to a molecular chaperone function

Although a great deal is known biochemically about peroxiredoxins (Prxs), little is known about their real physiological function. We show here that two cytosolic yeast Prxs, cPrxI and II, which display diversity in structure and apparent molecular weights (MW), can act alternatively as peroxidases and molecular chaperones. The peroxidase function predominates in the lower MW forms, whereas the chaperone function predominates in the higher MW complexes. Oxidative stress and heat shock exposure of yeasts causes the protein structures of cPrxI and II to shift from low MW species to high MW complexes. This triggers a peroxidase-to-chaperone functional switch. These in vivo changes are primarily guided by the active peroxidase site residue, Cys(47), which serves as an efficient "H(2)O(2)-sensor" in the cells. The chaperone function of these proteins enhances yeast resistance to heat shock.     

Multicenter evaluation of reverse line blot assay for detection of drug resistance in Mycobacterium tuberculosis clinical isolates

A multicenter study was conducted with the objective to evaluate a reverse line blot (RLB) assay to detect resistance to rifampin (RIF), isoniazid (INH), streptomycin (STR), and ethambutol (EMB) in clinical isolates of Mycobacterium tuberculosis. Oligonucleotides specific for wild type and mutant (drug resistance linked) alleles of the selected codons in the genes rpoB, inhA, ahpC, rpsL, rrs, embB, were immobilized on a nylon membrane. The RLB assay conditions were optimized following analysis of DNA samples with known sequences of the targeted genes. For validation of the method at different geographical locations, the membranes were sent to seven laboratories in six countries representing the regions with high burdens of multudrug-resistant tuberculosis. The reproducibility of the assay for detection of rpoB genotypes was initially evaluated on a blinded set of twenty reference DNA samples with known allele types and overall concordant results were obtained. Further mutation analysis was performed by each laboratory on the local strains. Upon RLB analysis of 315 clinical isolates from different countries, 132 (85.2%) of 155 RIF-resistant and 28 (51.0%) of 55 EMB-resistant isolates were correctly identified, showing applicability of the assay when targeting the rpoB hot-spot region and embB306. Mutations in the inhA and ahpC promoter regions, conferring resistance to INH, were successfully identified in respectively 16.9% and 13.2% of INH-resistant strains. Likewise, mutations in rrs513 and rpsL88 that confer resistance to STR were identified in respectively 15.1% and 10.7% of STR-resistant strains. It should be mentioned that mutation analysis of the above targets usually requires rather costly DNA sequencing to which the proposed RLB assay presents rapid and inexpensive alternative. Furthermore, the proposed method requires the same simple equipment as that used for spoligotyping and permits simultaneous analysis of up to 40 samples. This technique is a first attempt to combine different targets in a single assay for prediction of antituberculosis drugs resistance. It is open to further development as it allows easy incorporation of new probes for detection of mutations in other genes associated with resistance to second-line (e.g., fluoroquinolones) and new antituberculosis compounds.     

Accumulation of calcium and phosphorus accompanied by inevitable accumulation of magnesium in human arteries

To examine whether there were differences between races in regard to the relationships among element contents in the arteries, the authors investigated the relationships among the average contents of calcium, phosphorus, sulfur, and magnesium in the 18 kinds of the Thai artery. After ordinary dissection by medical students at Chiang Mai University was finished, the thoracic and abdominal aortas, ramifying site of the abdominal aorta into the common iliac arteries, coronary, common carotid, internal thoracic, subclavian, axillary, brachial, radial, superior and inferior mesenteric, renal, common iliac, internal iliac, and external iliac arteries were resected from the subjects who consisted of 12 men and 3 women, ranging in age from 39 to 84 yr. The femoral and posterior tibial arteries were resected from the subjects, consisting of 15 men and 5 women, ranging in age from 25 to 88 yr. The element content of the arteries was analyzed by inductively coupled plasma-atomic emission spectrometry. It was found that there were extremely significant direct correlations among the average contents of calcium, phosphorus, and magnesium in the 18 kinds of the Thai artery, but no significant correlations were found between the average contents of sulfur and elements, such as calcium, phosphorus, and magnesium. These results were in agreement with those of the Japanese arteries. Therefore, it was suggested that there was no significant difference between the arteries of the Thai and the Japanese in the relationships among calcium, phosphorus, sulfur, and magnesium.     

Deletion of secretory group V phospholipase A2 attenuates cell migration and airway hyperresponsiveness in immunosensitized mice

We investigated the role of group V phospholipase A2 (gVPLA2) in OVA-induced inflammatory cell migration and airway hyperresponsiveness (AHR) in C57BL/6 mice. Repeated allergen challenge induced biosynthesis of gVPLA2 in airways. By aerosol, gVPLA2 caused dose-related increase in airway resistance in saline-treated mice; in allergic mice, gVPLA2 caused persistent airway narrowing. Neither group IIa phospholipase A2, a close homolog of gVPLA2, nor W31A, an inactive gVPLA2 mutant with reduced activity, caused airway narrowing in immune-sensitized mice. Pretreatment with MCL-3G1, a blocking Ab against gVPLA2, before OVA challenge blocked fully gVPLA2-induced cell migration and airway narrowing as marked by reduction of migrating leukocytes in bronchoalveolar lavage fluid and decreased airway resistance. We also assessed whether nonspecific AHR caused by methacholine challenge was elicited by gVPLA2 secreted from resident airway cells of immune-sensitized mice. MCL-3G1 also blocked methacholine-induced airway bronchoconstriction in allergic mice. Blockade of bronchoconstriction by MCL-3G1 was replicated in allergic pla2g5-/- mice, which lack the gene encoding gVPLA2. Bronchoconstriction caused by gVPLA2 in pla2g4-/- mice was comparable to that in pla2g4+/+ mice. Our data demonstrate that gVPLA2 is a critical messenger enzyme in the development of AHR and regulation of cell migration during immunosensitization by a pathway that is independent of group IVa phospholipase A2.