Silver-modified octahedral anatase particles as plasmonic photocatalyst.

Octahedral anatase particles (OAPs) were modified with silver nanoparticles (NPs) by photodeposition method. The properties of OAPs influenced the properties of silver deposits, and thus the photocatalytic activity of the obtained silver-modified OAPs. Photocatalytic activities were tested under UV and vis irradiation for oxidative decomposition of acetic acid and oxidation of 2-propanol, respectively. The properties of silver-modified OAPs were investigated by XRD, STEM, DRS, XPS and time-resolved microwave conductivity (TRMC) method. It was found that electron traps (ETs) worked as nucleation sites for silver, resulting in formation of smaller silver NPs on smaller OAPs with larger content of ETs. The modification with silver resulted in enhanced photocatalytic activity under both UV and vis irradiation. It was found that larger crystallite size of silver NPs, and thus larger polydispersity of silver deposits resulted in broad and intense plasmon resonance peak causing enhanced visible activity. The correlation between photocatalytic activity and TRMC data, e.g., slower decay of TRMC signal for more active samples, allowed discussion on property-governed photocatalytic activities of silver-modified titania.

Biological activity of (lipo)polysaccharides of the exopolysaccharide-deficient mutant Rt120 derived from Rhizobium leguminosarum bv. trifolii strain TA1.

Lipopolysaccharides (LPS) from Rhizobium leguminosarum biovar trifolii TA1 (RtTA1) and its mutant Rt120 in the pssBpssA intergenic region as well as degraded polysaccharides (DPS) derived from the LPS were elucidated in terms of their chemical composition and biological activities. The polysaccharide portions were examined by methylation analysis, MALDI-TOF mass spectrometry, and (1)H NMR spectroscopy. A high molecular mass carbohydrate fraction obtained from Rt120 DPS by Sephadex G-50 gel chromatography was composed mainly of L-rhamnose, 6-deoxy-L-talose, D-galactose, and D-galacturonic acid, whereas that from RtTA1 DPS contained L-fucose, 2-acetamido-2,6-dideoxy-D-glucose, D-galacturonic acid, 3-deoxy-3-methylaminofucose, D-glucose, D-glucuronic acid, and heptose. Relative intensities of the major (1)H NMR signals for O-acetyl and N-acetyl groups were 1 : 0.8 and 1 : 1.24 in DPS of Rt120 and RtTA1, respectively. The intact mutant LPS exhibited a twice higher lethal toxicity than the wild type LPS. A higher in vivo production of TNFα and IL-6 after induction of mice with Rt120 LPS correlated with the toxicity, although the mutant LPS induced the secretion of IL-1ß and IFNγ more weakly than RtTA1 LPS. A polysaccharide obtained by gel chromatography on Bio-Gel P-4 of the high molecular mass material from Rt120 had a toxic effect on tumor HeLa cells but was inactive against the normal human skin fibroblast cell line. The polysaccharide from RtTA1 was inactive against either cell line. The potent inhibitory effect of the mutant DPS on tumor HeLa cells seems to be related with the differences in sugar composition.

Innate immunity to Legionella and toll-like receptors - review.

Legionella is a parasite of eukaryotic cells, able to survive and replicate in a wide range of protozoan hosts. It can also infect humans as an opportunistic pathogen, primarily by interaction with alveolar macrophages. These bacteria can cause life-threatening pneumonia, especially in immunocompromised individuals. However, most infections triggered by Legionella are cleared by an efficient host immune system. The protective immune responses against Legionella are complex and multifaceted, involving many components of the immune system. Recognition of such components as LPS, flagellum, and peptidoglycan of L. pneumophila by the TLRs, which orchestrates the innate immune responses to Legionella, lays an important role in activation of monocytes and alveolar macrophages and, thus, in inhibition of intracellular proliferation of bacteria. MyD88-dependent signaling pathways are important for host protection against Legionella.

H2O2/UV enhanced degradation of pesticides in wastewater.

Photodegradation of organic pesticides in industrial wastewater was examined in a UV/H2O2/air system. An experimentally determined optimal amount of hydrogen peroxide (0.008% v/v) indicates that hydrogen peroxide concentration controlled the efficiency of photodegradation. Pre-treatment operations such as sedimentation, filtration and coagulation were used to obtain better efficiency of pesticide removal and to cut down on irradiation time. Finally, scale-up experiments in the air-sparged hydrocyclone (ASH) reactor were carried out. After 5 min irradiation of 100 dm3 industrial wastewater almost all pesticides were destroyed. Thus the ASH reactor proved to be an effective contactor for carrying out photochemical reactions.

The Rhizobium leguminosarum bv. trifolii pssB gene product is an inositol monophosphatase that influences exopolysaccharide synthesis.

The pssB gene of Rhizobium leguminosarum bv. trifolii encodes a protein of 284 amino acids with sequence similarity to eukaryotic inositol monophosphatases. The gene was cloned and overexpressed in Escherichia coli. The purified gene product of pssB showed inositol monophosphatase activity with a Km of 0.23 mM, and a Vmax of 3.27 mumol Pi min-1 (mg protein)-1. Its substrate specificity, Mg+2 requirement, Li+ inhibition, and subunit association (dimerization) were studied and compared to those of other inositol monophosphatases. Western immunoblotting with anti-PssB antibodies showed the presence of PssB in R. leguminosarum bv. trifolii strain TA1 and lack of this protein in the pssB mutant strain Rt12A. The presence of PssB protein in R. leguminosarum bv. trifolii TA1 was correlated with phosphatase activity with myo-inositol 1-phosphate as a substrate. Evidence for a regulatory function of PssB protein in exopolysaccharide (EPS) synthesis is presented. The mutation in pssB caused EPS overproduction, and introduction of pssB into the wild-type TA1 strain reduced EPS synthesis. The changes in the level of EPS production were correlated with a non-nitrogen-fixing phenotype of rhizobia.

The pssB gene product of Rhizobium leguminosarum bv. trifolii is homologous to a family of inositol monophosphatases.

The Rhizobium leguminosarum bv. trifolii region encoding pssA and pssB genes was cloned. The pssB gene located upstream of the pssA encoded a 28.36-kDa protein which displayed 97.5% identity with the PssB of R. leguminosarum bv. viciae. Inactivation of the pssB gene by insertion of the lacZ-Gmr cassette resulted in the significant increased production of exopolysaccharide in comparison to the wild-type level. A mutant strain was also defective in nitrogen fixation suggesting a regulatory role of pssB in symbiosis with clover.

Pulsating mass after accidental artery trauma: diagnosis with duplex ultrasound and the role of angiography.

BACKGROUND: Pulsating mass located close to peripheral arteries is usually considered as a result of arterial wall injury. Clinically important is to distinct pseudoaneurysm from haematoma and also to evaluate proximal and distal arterial bed for the assessment of the injury extent. A few previous reports claim good results of duplex Doppler US diagnosis of iatrogenic (post-catheterization) femoral artery injuries. This paper presents diagnostic findings of arterial injuries caused by accidental trauma. PATIENTS AND METHODS: A retrospective analysis of 49 patients with post-traumatic pulsating mass close to peripheral artery was performed. The diagnostic results of both sonography and angiography were reviewed. All the patients underwent B-mode and duplex Doppler US examination using PW-, color- and power Doppler imaging techniques. RESULTS: 34 pseudoaneurysms were diagnosed correctly with typical B-mode, color/power Doppler images and PW-Doppler spectral waveforms. The lack of flow signal and distinctive B-mode images enabled proper diagnosis of 13 haematomas. In 2 patients duplex Doppler US misdiagnosis occurred, because of secondary pseudoaneurysm formation, primary diagnosed as haematoma. The 47 correct US findings gave 96% efficacy in distinguishing pseudoaneurysm from haematoma, which compares well with the other studies. In 20 patients suffering from peripheral ischemia, US examination, in spite of proper distinction between pseudoaneurysm and haematoma was unable for precise estimation of proximal and distal arterial damage. Thus, it was successfully supported with angiography before surgical decision making. Angiography was also necessary in 8 patients with severe injuries of carotid, subclavian and palmar arch arteries, hardly accessible for ultrasound penetration. CONCLUSIONS: We conclude that duplex Doppler US is essential for noninvasive, unequivocal distinction between pseudoaneurysm and haematoma but it could not completely replace contrast angiography in the evaluation of post-traumatic pulsating mass caused by severe, extensive trauma, frequently complicated with peripheral ischemia or located in regions with poor access for ultrasound penetration.

Power Doppler imaging in the evaluation of extracranial vertebral artery compression in patients with vertebrobasilar insufficiency.

OBJECTIVE: The recent introduction of Power Doppler Imaging (PDI) made a promise for better visualization of blood vessels lying in regions anatomically difficult for ultrasound imaging, i.e. vertebral arteries. The purpose of our study was to assess usefulness of PDI technique in visualization of vertebral artery course and to assess its utility in the detecting spondylotic vertebral artery compression in patients with vertebrobasilar insufficiency (VBI). METHODS: A total of 428 patients with VBI symptoms was evaluated. A total of 282 (66%) patients related their symptoms to a specific head position. Thus, all Doppler examinations were performed in four head positions: hyperextension, flexion and right/left rotation and also in a position reported by a patient to produce symptoms. PDI technique was employed as vertebral artery mapping for precise PW-Doppler range gate placing. RESULTS: Vertebral artery compression was found in 73 (17%) patients: 65 unilateral and eight bilateral. The diagnosis was based on flow decrease or its absence shown on PW-Doppler scans, after a specific head turning. CONCLUSION: Vertebral artery compression, related to a specific head position is relatively frequent in patients with VBI symptoms, especially in an older population commonly suffering from cervical spondylosis. PDI facilitates noninvasive Doppler US diagnosis by showing the real course of vertebral artery, particularly its intertransverse portion.