A time of flight mass spectrometer with field free interaction region for low energy charged particle-molecule collision studies.

A new design of a linear time of flight mass spectrometer (ToFMS) is implemented that gives nearly field-free interaction region without compromising on the mass resolution. The design addresses problems that would arise in a conventional Wiley-McLaren type of ToFMS: (i) field leakages into the charged particle-molecule interaction region from various components of the mass spectrometer, including that through the high transparency mesh used to obtain evenly distributed electric fields; (ii) complete collection and transportation of the ions produced in the interaction region to the detector, which is essential for high sensitivity and cross section measurements. This ToFMS works over a wide range of masses from H(+) to a few hundred Daltons and would be the most suitable for low energy charged particle-molecule interaction studies. Performance of the ToFMS has been tested by measuring the partial ionization cross sections for electron impact on CF(4).

Resumenes de articulos de la literatura pediatrica: profilaxis antimicrobiana para prevenir infecciones en la herida quirúrgica / Abstracts of articles in the pediatric literature: antimicrobial prophylaxis to prevent surgical wound infections

La infección en el sitio quirúrgico se define como un proceso que ocurre en o cerca de la incisión quirúrgica dentro los 30 días del procedimiento o durante el año si un implante ha sido instalado.

Proteomic changes in the photoreceptor outer segment upon intense light exposure.

Acute light-induced photoreceptor degeneration has been studied in experimental animals as a model for photoreceptor cell loss in human retinal degenerative diseases. Light absorption by rhodopsin in rod photoreceptor outer segments (OS) induces oxidative stress and initiates apoptotic cell death. However, the molecular events that induce oxidative stress and initiate the apoptotic cascade remain poorly understood. To better understand the molecular mechanisms of light-induced photoreceptor cell death, we studied the proteomic changes in OS upon intense light exposure by using a proteolytic (18)O labeling method. Of 171 proteins identified, the relative abundance of 98 proteins in light-exposed and unexposed OS was determined. The quantities of 11 proteins were found to differ by more than 2-fold between light-exposed OS and those remaining in darkness. Among the 11 proteins, 8 were phototransduction proteins and 7 of these were altered such that the efficiency of phototransduction would be reduced or quenched during light exposure. In contrast, the amount of OS rhodopsin kinase was reduced by 2-fold after light exposure, suggesting attenuation in the mechanism of quenching phototransduction. Liquid chromatography multiple reaction monitoring (LC-MRM) was performed to confirm this reduction in the quantity of rhodopsin kinase. As revealed by immunofluorescence microscopy, this reduction of rhodopsin kinase is not a result of protein translocation from the outer to the inner segment. Collectively, our findings suggest that the absolute quantity of rhodopsin kinase in rod photoreceptors is reduced upon light stimulation and that this reduction may be a contributing factor to light-induced photoreceptor cell death. This report provides new insights into the proteomic changes in the OS upon intense light exposure and creates a foundation for understanding the mechanisms of light-induced photoreceptor cell death.

Proteolytic 18O-labeling strategies for quantitative proteomics.

A number of proteomic techniques have been developed to quantify proteins in biological systems. This review focuses on the quantitative proteomic technique known as "proteolytic 18O-labeling." This technique utilizes a protease and H(2)18O to produce labeled peptides, with subsequent chromatographic and mass spectrometric analysis to identify and quantify (relative) the proteins from which the peptides originated. The technique determines the ratio of individual protein's expression level between two samples relative to each other, and can be used to quantitatively examine protein expression (comparative proteomics) and post-translational modifications, and to study protein-protein interactions. The present review discusses various aspects of the 18O-labeling technique, including: its history, the advantages and disadvantages of the proteolytic 18O-labeling technique compared to other techniques, enzymatic considerations, the problem of variable incorporation of 18O atoms into peptides with a discussion on recent advancements of the technique to overcome it, computational tools to interpret the data, and a review of the biological applications.

pH dependency of the carboxyl oxygen exchange reaction catalyzed by lysyl endopeptidase and trypsin.

The pH dependency of the carboxyl oxygen exchange reaction catalyzed by lysyl endopeptidase (Lys-C) and trypsin has been studied. The reaction was quantitatively monitored by measuring the incorporation of 18O atom into the alpha-carboxyl group of N(alpha)-acetyl-L-lysine from H2(18)O solvent. The optimum pHs of the carboxyl oxygen exchange reaction catalyzed by Lys-C and trypsin were found to be pH 5.0 and 6.0, respectively, which were significantly shifted toward acidic pHs compared to the most favorable pHs of their amidase activities for N(alpha)-acetyl-L-lysine amide in the pHs examined. Steady-state kinetics parameters were also determined for both enzymes at two different pHs, one at the pH optimum for their carboxyl oxygen exchange activity (pH 5-6) and the other at the favorable pH for their amidase activity (pH 8-9). Significantly lower Km (2-fold lower for Lys-C, 3-fold lower for trypsin), and higher kcat values (1.5-fold higher for Lys-C, 5-fold higher for trypsin) were obtained at the acidic pHs compared to the alkaline pHs, suggesting that Lys-C and trypsin have higher substrate binding affinities and higher catalytic rates at the acidic pHs than at the alkaline pHs. The higher carboxyl oxygen exchange activities at the acidic pHs were also confirmed with peptide substrates derived from apomyoglobin. These findings are significant toward the goal of improving the efficiency of the Lys-C and trypsin catalyzed 18O labeling reactions and are thus pertinent to improving the accuracy and reliability of quantitative proteomic experiments utilizing 18O labeling.

Peptidyl-Lys metalloendopeptidase-catalyzed 18O labeling for comparative proteomics: application to cytokine/lipolysaccharide-treated human retinal pigment epithelium cell line.

We recently proposed a comparative proteomic method utilizing proteolytic 18O labeling of peptides catalyzed by peptidyl-Lys metalloendopeptidase (Lys-N) (Rao, K. C. S., Carruth, R. T., and Miyagi, M. (2005) Proteolytic 18O labeling by peptidyl-Lys metalloendopeptidase for comparative proteomics. J. Proteome Res. 4, 507-514). Unlike trypsin, which generates a mixture of isotopic isoforms resulting from the incorporation of one or two 18O atoms into each peptide species, Lys-N incorporates only a single 18O atom into the carboxyl terminus of each proteolytically generated peptide in H2(18)O solvent. This study reports the first biological application of the Lys-N-based proteolytic 18O labeling method, characterizing the proteome changes of cytokine/lipopolysaccharide-treated verses untreated human retinal pigment epithelium (ARPE-19) cells. The study resulted not only in the identification of 584 proteins but also the determination of the relative abundances of 562 proteins in the two proteomes. The results demonstrate the usefulness of the Lys-N-based proteolytic 18O labeling method in comparative proteomic studies. The results also provide the most comprehensive description of the retinal pigment epithelium proteome to date.

Proteolytic 18O labeling by peptidyl-Lys metalloendopeptidase for comparative proteomics.

The potential capabilities of a new proteolytic 18O labeling method employing peptidyl-Lys metalloendopeptidase (Lys-N) have been demonstrated for use in comparative proteomics. Conditions (pH>or=9.5) have been found such that Lys-N incorporates only a single 18O atom into the carboxyl terminus of each proteolytically generated peptide. This 18O labeling method has a major advantage over current protelytic 18O labeling methods that generate a mixture of isotopic isoforms resulting from the incorporation of one or two 18O atoms into each peptide species by the proteases (trypsin, Lys-C, or Glu-C) used. We demonstrate that the single 18O atom incorporation property of Lys-N overcomes the major problem of the current proteolytic 18O labeling methods and provides accurate quantification results for isotopically labeled peptides.

A spectroscopic study of the interaction of nigerloxin, a fungal metabolite, with serum albumin.

Nigerloxin [2-amido-3-hydroxy-6-methoxy-5-methyl-4-(prop-1'-enyl) benzoic acid], a fungal metabolite, is an inhibitor of lipoxygenase and aldose reductase with free radical-scavenging properties. The interaction of nigerloxin with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy and circular dichroic measurements. The fluorescence of BSA was quenched following interaction with nigerloxin, and this property was used to generate a binding constant. The estimated association constant was 1.01 +/- 0.2 x 10(6) M(-1). Job's method of continuous variation indicated that nigerloxin formed a 1:1 +/- 0.1 complex with BSA. To understand the nature of the interaction, the variance in the association constant as a function of temperature in the range of 14-45 degrees C was used to calculate the thermodynamic parameters. The thermodynamic parameters at 27 degrees C derived from the mass action plot and van't Hoff's plot were as follows: deltaG = -8.2 +/- 0.1 kcal/mol, deltaH approximately equal to 0 kcal/mol, and deltaS = 27.5 +/- 0.4 cal/mol/K (where deltaG is free energy, deltaH is enthalpy, and deltaS is entropy). Increasing ionic strength did not favor interaction. Circular dichroic measurements revealed that the interaction of nigerloxin with BSA did not lead to changes in the secondary structure of the protein. The reversibility of the interaction verified by the dilution method was found to be reversible. These measurements suggest that partial hydrophobic and partial ionic bonding play a role in the interaction of nigerloxin with BSA.

Nigerloxin, a novel inhibitor of aldose reductase and lipoxygenase with Free radical scavenging activity from Aspergillus niger CFR-W-105.

An enzyme inhibitor, nigerloxin, with inhibition against soy bean lipoxygenase-I (LOX-1), rat lens aldose reductase (RLAR) as well as free radical scavenging activity was isolated from the fermented wheat bran using Aspergillus niger CFR-W-105. Its chemical structure was identified as 2-amido-3-hydroxy-6-methoxy-5-methyl-4-(prop-1'-enyl) benzoic acid by NMR and GCEIMS data. The IC50 values against LOX-1 and RLAR were found to be 79 microM and 69 microM and ED50 against 1,1-diphenyl-2-picrylhydrazyl (DPPH) was 66 microM.

A lipoxygenase inhibitor from Aspergillus niger.

A lipoxygenase-1 (LOX-1) inhibitor was isolated from the fermented broth of Aspergillus niger CFTRI 1105. It was purified, using column and preparative thin layer chromatography. 1H NMR and GC-MS examination revealed the structure of the inhibitor to be 2-(2'-methyl, 4'-hydroxyphenyl), 2-(4"hydroxyphenyl)-propane with a molecular weight of 242 and the molecular formula C,6H18O2. This bisphenol-derivative inhibitor shows 50% inhibition of soybean LOX-I at 0.98 mM concentration. The activity of this inhibitor was compared with commercial bisphenol A and its structural analogues, butylhydroxyanisole and butylhydroxytoluene in an attempt to understand the role of functional groups affecting lipoxygenase activity.

Intratentorial lipomas with Meckel's cave and cerebellopontine angle extension.

An unusual case of bilateral intratentorial lipomas with extension into Meckel's caves and the cerebellopontine angle is described. Surgical and histopathologic correlation demonstrate that the lipoma encased the trigeminal nerve in Meckel's caves. The origin of the lipoma from the anteromedial margins of the tentorium is discussed and correlated with a recently proposed theory for the development of intracranial lipomas.

Adenocarcinoma production in rats administered 1,2-dimethylhydrazine and fed iron salt and guar gum diets.

Iron salts supplemented in a basal ratio, were fed to young Sprague-Dawley male rats for prolonged periods and the frequency of colonic adenocarcinomas induced by repeated s.c. injection of 1,2-dimethylhydrazine (DMH) at unit base doses of 9.0 mg/kg, ascertained and compared with the respective controls. In a series employing ferric ammonium citrate (0.46% Fe), in addition to ferrous sulfate (0.11% Fe) and ferric ammonium sulfate (0.12% Fe), DMH injection was started on day 15 and the animals necropsied 22 weeks after the last of 23 doses. The general condition was more involved with the 0.46% Fe diet and the total colonic lesion numbers were in the control range. However, the ferric ammonium sulfate-fed group showed a significant increase in tumors in the distal colon portion. In the second experiment, 15% guar gum as such and in admixture with ferric ammonium sulfate (0.12%) were compared with the respective controls, the first of 20 weekly dosages of DMH being administered on day 28 of the feeding. At 32 weeks following injection 1, the overall lesion differences were not remarkable, but the guar gum ratios engendered decreases in the distal colon tumor frequencies. In general, lesion incidence was extensive, involving 80-100% of the animals per group of the 2 series. Adenocarcinomas occurred in the small intestine and were more prominent in the control and 15% guar gum dietary groups but fewer with the ferric ammonium sulfate supplement.

Bacterial aerosol emission rates from municipal wastewater aeration tanks.

In this report we describe the results of a study conducted to determine the rates of bacterial aerosol emission from the surfaces of the aeration tanks of the Metropolitan Water Reclamation District of Greater Chicago John E. Egan Water Reclamation Plant. This study was accomplished by conducting test runs in which Andersen six-stage viable samplers were used to collect bacterial aerosol samples inside a walled tower positioned above an aeration tank liquid surface at the John E. Egan Water Reclamation Plant. The samples were analyzed for standard plate counts (SPC), total coliforms (TC), fecal coliforms, and fecal streptococci. Two methods of calculation were used to estimate the bacterial emission rate. The first method was a conventional stack emission rate calculation method in which the measured air concentration of bacteria was multiplied by the air flow rate emanating from the aeration tanks. The second method was a more empirical method in which an attempt was made to measure all of the bacteria emanating from an isolated area (0.37 m2) of the aeration tank surface over time. The data from six test runs were used to determine bacterial emission rates by both calculation methods. As determined by the conventional calculation method, the average SPC emission rate was 1.61 SPC/m2/s (range, 0.66 to 2.65 SPC/m2/s). As determined by the empirical calculation method, the average SPC emission rate was 2.18 SPC/m2/s (range, 1.25 to 2.66 SPC/m2/s). For TC, the average emission rate was 0.20 TC/m2/s (range, 0.02 to 0.40 TC/m2/s) when the conventional calculation method was used and 0.27 TC/m2/s (range, 0.04 to 0.53 TC/m2/s) when the empirical calculation method was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Action of hydrazine drugs in tumor-free and 1,2-dimethylhydrazine-treated male rats.

In order to evaluate possible carcinogenesis, young adult male Sprague-Dawley rats were fed diets of hydralazine, phenelzine, and isoniazid at levels of 0.020-0.035% for 87 weeks. Hydralazine and isoniazid were also tested by the subcutaneous (sc) route at weekly dosages of 17 and 83 mg/kg, respectively, in both intact and partially hepatectomized rats, but many succumbed after 7 to 49 weeks of treatment. Gastrointestinal lesions were absent and, of the miscellaneous changes, sc lesions occurred sporadically among the control and drug-treated groups. As a further criterion, male weanlings were placed on the diets and, starting on day 15, 1,2-dimethylhydrazine (DMH) was injected sc at 9.0 mg/kg once weekly for the first 7 weeks and twice per week for a total of 23 treatments. The rats were killed 22 weeks after the last injection, at which time colon adenocarcinomas were observed in over 80% per group, the total number being significantly greater for the isoniazid group due to heightened tumor occurrence at the distal colon. The tumor number in the descending colon for phenelzine was also increased but the overall score, as with the hydralazine group, was in the range of the DMH injected controls. Small intestinal adenocarcinomas were lower in number and involved fewer rats on the hydralazine and phenelzine diets as compared to the isoniazid and control groups. Based on the current data, it is concluded that on long term exposure of DMH treated rats to the monoamine oxidase inhibitors, hydralazine and phenelzine are not cocarcinogenic, whereas isoniazid enhances colon carcinogenicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoid tumor with intradural spinal metastases.

A case of spinal intradural metastasis from a carcinoid tumor is reported. The case is of interest due to the rarity of central nervous system involvement by these tumors and the long latency period of the patient's presentation.