Mechanism of irreversible inactivation of phosphomannose isomerases by silver ions and flamazine

Silver ions and silver-containing compounds have been used as topical antimicrobial agents in a variety of clinical situations. We have previously shown that the enzyme phosphomannose isomerase (PMI) is essential for the biosynthesis of Candida albicans cell walls. In this study, we find that PMI can be inhibited by silver ions. This process is shown to be irreversible, and is a two-step process, involving an intermediate complex with a dissociation constant, Ki, of 59 +/- 8 microM, and a maximum rate of inactivation of 0.25 +/- 0.04 min-1 in 50 mM Hepes buffer, pH 8.0 at 37 degrees C. The enzyme can be protected against this inactivation by the substrate mannose 6-phosphate, with a dissociation constant of 0.31 +/- 0.04 mM, close to its Km value. Flamazine (silver sulfadiazine) is a silver-containing antibiotic which is used clinically as a topical antimicrobial and antifungal agent. We compared the ability of silver sulfadiazine and two other silver-containing compounds to irreversibly inactivate C. albicans PMI. The addition of the organic moiety increased the affinity of the compounds, with silver sulfadiazine showing a Ki of 190 +/- 30 nM. In all cases, the maximum inhibition rate was similar, implying a similar rate-determining step. Silver sulfadiazine does not inhibit Escherichia coli PMI, and this suggests a role of the only free cysteine, Cys-150, in the inactivation process. To confirm this, we mutated this residue to alanine in C. albicans PMI. The resultant Cys150 --> Ala mutant protein showed similar Vm and Km values to the wild-type enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fertility and schizophrenia: evidence for increased fertility in the relatives of schizophrenic patients

BACKGROUND AND PURPOSE: We present a rare case of desmoplastic fibroma of the skull. Desmoplastic fibroma is a distinctive and rare neoplasm of bone that histologically and biologically mimics desmoid soft tissue tumor. Only 6 cases have been reported in the skull and none of these was diagnosed by MRI. CLINICAL PRESENTATION: A 64 year-old woman, operated on in June 1991 for left mastectomy due to a ductal adenocarcinoma and again in October 1994 for a left frontal metastatic adenocarcinoma, was admitted in our Department of Neurosurgery because a control cerebral MRI had detected a diploic lesion, isointense on T1-weighted images and hyperintense on T2, with moderate enhancement, localized in a right parietal site. Neurological examination was negative. The lesion was surgically removed and a cranioplasty was performed. Histological diagnosis was desmoplastic fibroma. Twelve months after treatment she has no neurological symptoms or signs of cerebral lesions (MRI) or systemic metastasis (total body CT). CONCLUSION: In the literature the number of desmoplastic fibroma is too small and the follow-up period too short to permit any conclusions regarding the aggressiveness of the tumor.     

Spinal cord herniation after stabbing injury

The commercially available spray management valve provided consistent flow rates when used with hand-compression sprayer systems. The 15-psi spray management valve maintained a constant flow rate of 180, 150, and 155 ml/min in combination with a fine 45 degrees flat fan nozzle and Hudson. B&G, and Chapin hand-compression sprayers, respectively. The 30-psi spray management valve maintained a constant flow rate and adequate spray-on time when combined with the coarse flat fan nozzle for each of the 3 hand-compression sprayers tested.     

Controlling thickness to tune performance of high-mobility transparent conducting films deposited from Ga-doped ZnO ceramic target

Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm²/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm²/Vs, low resistivity of 5.3 × 10^?4 Ωcm, and good transmittance of 83.3 %.     

Decontamination of petroleum sludges by hot water extraction

The process of hot water extraction of tar sand was modified and adapted for removal of heavy oil from bottom tank petroleum sludges, and was submitted to a laboratory feasibility study. This process can also be utilized to clean beach sands contaminated by accidental heavy oil spills. In the case of oil contaminated sands, a single stage extraction has yielded a 99% recovery of hydrocarbons and clean sands (containing less than 0.1% of hydrocarbons) which are thus safe to be returned to the environment. In the case of petroleum bottom tank sludge, it was necessary to proceed with a double stage extraction with the addition of a wetting agent. A dosage of a Na₂ Si O₃ aqueous solution of 1% by weight has proven efficient, allowing an 82% recovery of hydrocarbons, with only 0.5% of hydrocarbons content in the solid residues.     

The effects of air pollution and climatic factors on atmospheric corrosion of marble under field exposure

The atmospheric corrosion of marble was evaluated in terms of SO₂ concentration as air pollution and climatic factors such as rainfall, relative humidity, temperature and so on under the field exposure. Marble of calcite type (CaCO₃) was exposed to outdoor atmospheric environment with and without a rain shelter at four test sites in the southern part of Vietnam for 3-month, 1- and 2-year periods from July 2001 to September 2003. The thickness loss of marble was investigated gravimetrically. X-ray diffraction and X-ray fluorescent methods were applied to study corrosion products on marble. The corrosion product of marble was only gypsum (CaSO₄ · 2H₂O) and was washed out by rain under the unsheltered exposure condition. It was found that the most substantial factors influencing the corrosion of marble were rainfall, SO₂ concentration in the air and relative humidity. Based on the results obtained, we estimated the dose-response functions for the atmospheric corrosion of marble in the southern part of Vietnam.     

Direct evidence of oxygen evolution from Li1+ x (Ni1/3Mn1/3Co1/3)1? x O2 at high potentials

Li_1+x (Ni_1/3Mn_1/3Co_1/3)_1−x O₂ (NMC) oxides are among the most promising positive electrode materials for future lithium–ion batteries. A voltage “plateau” was observed on the first galvanostatic charging curve of NMC in the extended voltage region positive to 4.5 V vs. Li/Li⁺ for compounds with x > 0 (overlithiated compounds). Differences were observed in the cycling stability of the overlithiated and stoichiometric (x = 0) NMC oxides in this potential region. A differential plot of the charge vs. potential profile in the first cycle revealed that, for the overlithiated compounds, a large irreversible oxidative peak arises positive to 4.5 V vs. Li/Li⁺, while in the same potential region only a small peak due to the electrolyte oxidation is detected for the stoichiometric material. Differential Electrochemical Mass Spectrometry (DEMS) was used to investigate the high voltage region for both compounds and experimental evidence for oxygen evolution was provided for the overlithiated compounds at potentials positive to 4.5 V vs. Li/Li⁺. No oxygen evolution was detected for the stoichiometric compound.     

Chemical and nutritional quality of silage made from raw or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus)

Twelve silages were prepared from uncooked or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus) and stored at ambient temperature (30 ± 2 °C) for 60 days. The antioxidative effect of adding ethoxyquin was also investigated. Generally, the nutritional quality of all the silages was stable for up to 60 days of storage and the composition of raw materials was reflected in the composition of the silages. Crab had a lower level of crude protein than fish (85 versus 162 mg kg^?1), but a higher level of ash (96 versus 36 g kg^?1); moreover, there were significant differences in nutritional composition between uncooked and cooked materials. High level of ash in crab required addition of high levels of formic acid in crab‐related silages. At the end of the experiment cooked silages showed a tendency for spoilage; in particular, maggots were observed in cooked crab silages on the last few days of the experiment. Comparison of treatments with or without ethoxyquin showed that only rancidity of fish silage groups was higher without addition of ethoxyquin. Uncooked materials are more suitable for prolonged storage than cooked materials, and it is probably not necessary to add antioxidants to silages made from material with low lipid content. Copyright © 2009 Society of Chemical Industry     

Simultaneous measurement of one- and two-photon excited fluorescence from a single sample: a detection method for oligonucleotides

A new method has been developed that is based on the use of a single-excitation wavelength from a cw laser to excite simultaneously one-photon and two-photon fluorescence (TPF). Fluorescence bands of a sample containing two oligonucleotides, one labeled with a one-photon fluorescence dye and the other with a TPF dye, can be measured simultaneously. The two fluorescence bands are well separated, because the one-photon excited fluorescence band is redshifted, whereas the TPF band is blueshifted from the excitation wavelength. The spectral separation was found to be as large as 200 nm when ADS 840NCS was used to label one oligonucleotide for one-photon fluorescence and Rhodamine Red-X dye was used for TPF. Spectral overlapping problem that plagues current DNA sequencing techniques can be eliminated effectively with this method.