Development of a chemiluminescent enzyme immunoassay for urinary 1-hydroxypyrene

A chemiluminescent enzyme-immunoassay for urinary 1-hydroxypyrene has been developed and optimized. The enzymatic activity of horseradish peroxidase-labeled tracer was measured with an enhanced chemiluminescent system and the results were compared with those from conventional colorimetric detection. The method fulfilled all the requirements of accuracy and precision and the detection limit was 0.001 pmol/well, which enabled analysis in less than 1 microL urine. Subjects working in the center of Bologna who were exposed daily to vehicular exhaust gas were studied. Their urinary 1-hydroxypyrene concentrations were compared with the levels of benzo( a)pyrene in air particulate matter. Urinary 1-hydroxypyrene, which ranged from 0.5 to 10 nmol L(-1), correlated poorly with the concentration of benzo( a)pyrene in air particulate matter, which ranged from 5 to 140 ng m(-3). No significant effect of vehicle exhaust gas exposure was observed among the different groups of subjects working in different areas of the town. Thus, at a relatively low level of exposure 1-hydroxypyrene does not seem to be a sensitive biomarker of exposure to polycyclic aromatic hydrocarbons.     

THE EFFECTS OF LIQUID HOLDING ON NEAR-UV(300–400 nm) IRRADIATED ESCHERICHIA COLI STRAINS DIFFERING IN NEAR AND FAR-UV RADIATION SENSITIVITY

Abstract— Stationary phase cells from four Escherichia coli strains differing in near- (nur vs. nur ₊) and far-UV (recAl vs. recA₊) radiation sensitivity were subjected to near-UV radiation (NUV) in 0.85% saline. Although the NUV-irradiated cultures yielded increased colony numbers following 24 h of liquid holding (LH), a fluctuation test for each experiment showed that the observed increases were not due to recovery but were in fact due to cell multiplication. The decline in viability observed after NUV with liquid holding using the fluctuation test was equivalent in strains RT2, 3 and 4 while the decline observed with RT1 was less marked. The discrepancy between LH involving cell densities of 10₈-10₉ and 1–4 cells/m/ can be resolved by assuming that with dense cell suspensions, NUV-induced membrane damage leads to leakage or lysis, supplying sufficient nutrients to allow growth of undamaged, surviving cells.     

A new high-performance liquid chromatographic/electrospray ionization tandem mass spectrometric method for the simultaneous determination of cyclophosphamide, methotrexate and 5-fluorouracil as markers of surface contamination for occupational exposure monitoring

A new high-performance liquid chromatographic/electrospray ionization tandem mass spectrometric (HPLC/ESI-MS/MS) method was developed for the simultaneous quantification of 5-fluorouracil (5FU), methotrexate (MTX) and cyclophosphamide (CP) in environmental samples. These compounds, commonly used in the treatment of cancer, are recognized as genotoxic. In order to estimate the occupational exposure of hospital personnel handling these drugs, wipe samples were taken from the working surfaces and directly analyzed (with trophosphamide as internal standard) using a reversed-phase capillary column and MS/MS detection. This is the first HPLC/MS/MS method for the simultaneous determination of 5FU, MTX and CP. The present method offers high sensitivity, with detection limits of 1.1 microg l(-1) for MTX and CP and 33.3 microg l(-1) for 5FU, avoiding any sample preconcentration procedure. Rapidity, specificity, high accuracy (mean values between 92.4 and 99.9%) and precision (mean RSD values between 3.4 and 12.1%) make the method suitable for the routine determination of these three antineoplastic drugs.     

The mechanism of Sandmeyer's cyclization reaction by electrospray ionization mass spectrometry

Using electrospray ionization (tandem) mass spectrometry (ESI-MS(/MS)) spectrometric experiments, the Sandmeyer reaction was monitored on-line, and key intermediates were intercepted and characterized for the first time. The mechanistic information provided by on-line ESI-MS(/MS) is in accordance with Sandmeyer's proposal, and was made possible by coupling a microreactor on-line to the ESI ion source, which allowed reactions to be screened from 0.7-2.0 s, identifying and characterizing all intermediates that were formed and consumed during the reaction.     

Reversible coordinative chain transfer polymerization of styrene by rare earth borohydrides,chlorides/dialkylmagnesium systems

The ability of various rare earth borohydride and chloride complexes/n‐butylethylmagnesium systems to operate styrene chain transfer polymerization in mild conditions has been assessed. Thirteen precatalysts have been considered: the rare earth trisborohydrides Ln(BH₄)₃(THF)_x (x = 3, Ln = Nd (1), La (2), Sm (3), x = 2, Ln = Y (4), Sc (5)), the rare earth chlorides LnCl₃(THF)_x (x = 3, Ln = Nd (6), La (7), Sm (8), Y (9), x = 2, Ln = Sc (10)), the mixed La(BH₄)₂Cl(THF)_2.6 (11) and the half‐lanthanidocenes Cp*Ln(BH₄)₂(THF)₂ (Ln = Nd (12), La (13)). Six systems were found to be active precatalysts for the polymerization of styrene. 1 , 2 , and 11 led to an efficient transmetalation of the growing polystyrene chain with the simultaneous occurrence of βH elimination, whereas 7 , 12 , and 13 led to catalyzed chain growth behavior. It is noteworthy that the catalyzed chain growth obtained with 12 and 13 occurs with significant stereoselectivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 802–814, 2010     

Marginal Density Expansions for Diffusions and Stochastic Volatility I: Theoretical Foundations

Density expansions for hypoelliptic diffusions (X¹,…,X^d) are revisited. We are particularly interested in density expansions of the projection at time T > 0 with l ≤ d. Global conditions are found that replace the well‐known “not‐in‐cut‐locus” condition known from heat kernel asymptotics. Our small‐noise expansion allows for a “second order” exponential factor. As an application, new light is shed on the Takanobu‐Watanabe expansion of Brownian motion and Lévy's stochastic area. Further applications include tail and implied volatility asymptotics in some stochastic volatility models, discussed in the companion paper 12 .© 2013 Wiley Periodicals, Inc.     

Hair analysis and the early detection of imbalances in trace elements for members of expeditions in Antarctica

In the framework of the Human Biology and Medicine Project of the National Program for Research in Antarctica (Programma Nazionale di Ricerche in Antartide, PNRA) a study was undertaken to explore the suitability of trace element determination in human hair as a tool for the early detection of the impact of extreme environmental conditions on the health of members of the Italian and French expeditions. This study included three campaigns, namely, the 1995–1996 expedition to the Italian base of Terra Nova Bay, as well as the 1997–1998 and 1998–1999 expeditions to both the Italian base of Terra Nova Bay and the Italian–French base of Dome C. Sampling of hair of participants in the expeditions was carried out both prior to departure and at the end of the period spent at the bases. As regards storage, pre-treatment and analysis of hair samples they were performed in accordance with previously established procedures. Acid-assisted microwave digestion was adopted as the best approach for preparing solutions for subsequent analysis by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. In the first part of this study, only the elements Ca, Cu, Fe, Mg and Zn were selected, while at a later stage it was decided to also include Co, Cr, Mn, Mo and Ni. Experimental results were subjected to basic statistical analysis to detect possible significant differences in element concentrations that occurred during the sojourn at the bases, with a view to identify possible remedial action to minimize adverse consequences.     

A Modified Version of the Grimm's Glow Discharge Lamp for Use as a Demountable Hollow Cathode Emission Source. III. Blackening as a Function of Discharge Parameters

Abstract

The influence of anode distance from hollow cathode on the blackening? of spectral lines excited by means of the modified Grimm's lamp was investigated for three representative cathodic materials, i.e. aluminium, copper and graphite using argon as the carrier gas. On the basis of the experimental results as well as voltage-current characteristic curves at distances of 7, 15, 20, 25 and 33 mm, it was possible to conclude that the optimal sets of discharge parameters for all the materials investigated are based on an electrode distance of 20-25 mm. In the case of copper a distance of 33 mm was also found to be highly suitable. An increase in the emission of copper lines at the largest anodic length with increasing pressure of the noble gas was also observed, in contrast with the behavior of the same element at shorter distances. A tentative interpretation of the phenomenon is given.     

Applicability of Spectroscopic Methods to the Determination of Aluminium in Biological Samples

A comparative investigation was carried out of the suitability of atomic absorption spectrometry and of emission spectrography with hollow cathode and arc excitation sources for determination of aluminium in biological samples. The three methods give reliable results. Hollow cathode emission spectrography was found to be influenced to a lesser extent by matrix effects than the other two techniques. On the other hand atomic absorption spectrometry presents some remarkable advantages insofar rapidity of analysis and detection limits are concerned.     

Simultaneous quantification of 17 trace elements in blood by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) equipped with a high-efficiency sample introduction system

A quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS) equipped with a dynamic reaction cell (DRC) and coupled with a desolvating nebulization system (APEX-IR) was employed to determine 17 elements (Al, As, Ba, Cd, Co, Cr, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zr) in blood samples. Ammonia (for Al, Cr, Mn, and V) and O₂ (for As and Se) were used as reacting gases. Selection of the best flow rate of the gases and optimization of the quadrupole dynamic bandpass tuning parameter (RPq) were carried out, using digested blood diluted 1 + 9 with deionized water and spiked with 1 μg L⁻¹ of Al, Cr, Mn, V and 5 μg L⁻¹ of As and Se. Detection limits were determined in digested blood using the 3σ criterion. The desolvating system allowed a sufficient sensitivity to be achieved to determine elements at levels of ng L⁻¹ without detriment of signal stability. The accuracy of the method was tested with the whole blood certified reference material (CRM), certified for Al, As, Cd, Co, Cr, Mn, Mo, Ni, Pb, Sb, Se, and V, and with indicative values for Ba, Li, Sn, Sr, and Zr. The addition calibration approach was chosen for analysis. In order to confirm the DRC data, samples were also analyzed by means of sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), operating in medium (m/Δm = 4000) and high (m/Δm = 10,000) resolution mode and achieving a good agreement between the two techniques.