Implementing tandem mass spectrometry as a routine tool for characterizing the complete purine and pyrimidine metabolic profile in urine samples

Purines and pyrimidines are the basic constituents of DNA and RNA and constitute the basis of at least 50 other important compounds that serve equally vital but separate roles as integral components of intracellular mononucleotide pools. They maintain the supply of these basic components to the different nucleotide pools through an extremely efficient mechanism involving the degradation and recycling of the daily waste products of normal cell turnover. We have developed an LC-MS/MS diagnostic and routine monitoring method for known defects due to both purine and pyrimidine metabolism in a single analysis. Precision tests were made by spiking several urine samples with different creatinine concentrations. For nonspiked low-creatinine urine, intraday precision was in the range of 0.1-9.8% and interday precision was between 1.6 and 14.1%. For nonspiked high-creatinine urine, intraday precision was in the range 0.5-17.2% and interday precision was between 1.5 and 29%. Limit-of-detection (LOD) was in the range 0.1-10 micromol/l and limit-of-quantification (LOQ) in the range of 0.2-15 micromol/l. The current 'dilute and shoot' approach monitors many metabolites, and utilizes a reverse phase chromatographic analysis with a detection requiring 17 min of analysis time. Tandem mass spectrometry and isotope dilution technique enable the accurate quantitation of more than 30 metabolites in one analysis.     

Effects of HeNe laser irradiation on experimental paracoccidioidomycotic lesions

Paracoccidioidomycosis (PCM) is the most prevalent human mycosis in Latin America. The infection is thought to take place firstly in the lungs and then may disseminate to other organs and tissues. Treatment by currently available antifungals is lengthy, the drugs may have undesirable side effects, and some are costly. Occasional resistant strains of Paracoccidioides brasiliensis, the causative agent of PCM, have been reported. So, the search for more efficient treatments or adjuvant therapies has to be continued. In this work, we evaluated the effects of HeNe laser irradiation on cutaneous inflammatory lesions caused by the inoculation of 5 x 10(6)/0.1ml yeasts cells into the back footpad of Balb/c mice. HeNe irradiation (lambda=632.8nm, 3mW, incident energy of 3J/cm(2)) was applied at days 7, 8 and 9 post-infection and histological and immunohistochemical analysis were done. Unirradiated animals were used as controls. The results showed that laser-treated mice presented reduction of footpad edema, faster cutaneous wound healing, confluent granuloma, diffuse- and more loosely distributed immunolabeling for TNF-alpha, enhanced labeling of IFN-gamma and any P. brasiliensis form detected, whereas multiple viable fungi were seen in diffuse widespread granulomas obtained from non-treated mice foot-pad. Fungi that were harvested from laser-treated animals presented no capability of growth in vitro as compared to those obtained from non-treated mice. We conclude that HeNe laser irradiation was able to inhibit the progress of inflammatory local reaction produced by P. brasiliensis infection and influence local cytokines production. We suggest that this treatment modality can be a useful coadjuvant tool to be combined with antifungal agents in the treatment of PCM ulcerations. The mechanisms involved in laser therapy of PCM lesions need further investigation.     

Novel, efficient total synthesis of natural 20(S)-camptothecin

Enantiopure 20(S)-camptothecin has been prepared from a known hydroxypyridone through a novel approach that involves a Claisen rearrangement, an asymmetric nucleophilic ethylation, a Heck coupling and a Friedl?nder condensation as the key transformations.     

Cellular and antitumor activity of a new diethylene glycol benzoporphyrin derivative (lemuteporfin)

A newly synthesized diethylene glycol functionalized chlorin-type photosensitizer, lemuteporfin, was characterized for use in photodynamic therapy (PDT) in a panel of in vitro and in vivo test systems. The photosensitizer was highly potent, killing cells at low nanomolar concentrations upon exposure to activating light. The cellular uptake of lemuteporfin was rapid, with maximum levels reached within 20 min. Mitogen-activated lymphoid cells accumulated more of the lemuteporfin than their quiescent equivalents, supporting selectivity. Photosensitizer fluorescence in the skin increased rapidly within the first few minutes following intravenous administration to mice, then decreased over the next 24 h. Skin photosensitivity reactions indicated rapid clearance of the photosensitizer. Intravenous doses as low as 1.4 micromol/kg combined with exposure to 50 J/cm2 red light suppressed tumor growth in a mouse model. In conclusion, this new benzoporphyrin was found to be an effective photosensitizer, showing rapid uptake and clearance both in vitro and in vivo. This rapid photosensitization of tumors could be useful in therapies requiring a potent, rapidly accumulating photosensitizer, while minimizing the potential for skin photosensitivity reactions to sunlight following treatment.     

Hybrid feedforward-feedback active noise reduction for hearing protection and communication

A hybrid active noise reduction (ANR) architecture is presented and validated for a circumaural earcup and a communication earplug. The hybrid system combines source-independent feedback ANR with a Lyapunov-tuned leaky LMS filter (LyLMS) improving gain stability margins over feedforward ANR alone. In flat plate testing, the earcup demonstrates an overall C-weighted total noise reduction of 40 dB and 30-32 dB, respectively, for 50-800 Hz sum-of-tones noise and for aircraft or helicopter cockpit noise, improving low frequency (<100 Hz) performance by up to 15 dB over either control component acting individually. For the earplug, a filtered-X implementation of the LyLMS accommodates its nonconstant cancellation path gain. A fast time-domain identification method provides a high-fidelity, computationally efficient, infinite impulse response cancellation path model, which is used for both the filtered-X implementation and communication feedthrough. Insertion loss measurements made with a manikin show overall C-weighted total noise reduction provided by the ANR earplug of 46-48 dB for sum-of-tones 80-2000 Hz and 40-41 dB from 63 to 3000 Hz for UH-60 helicopter noise, with negligible degradation in attenuation during speech communication. For both hearing protectors, a stability metric improves by a factor of 2 to several orders of magnitude through hybrid ANR.     

Codistances of 3-spherical buildings

We show that a 3-spherical building in which each rank 2 residue is connected far away from a chamber, and each rank 3 residue is simply 2-connected far away from a chamber, admits a twinning (i.e., is one half of a twin building) as soon as it admits a codistance, i.e., a twinning with a single chamber.     

MCMC calibration of spot‐prices models in electricity markets

The calibration of some stochastic differential equation used to model spot prices in electricity markets is investigated. As an alternative to relying on standard likelihood maximization, the adoption of a fully Bayesian paradigm is explored, that relies on Markov chain Monte Carlo (MCMC) stochastic simulation and provides the posterior distributions of the model parameters. The proposed method is applied to one‐ and two‐factor stochastic models, using both simulated and real data. The results demonstrate good agreement between the maximum likelihood and MCMC point estimates. The latter approach, however, provides a more complete characterization of the model uncertainty, an information that can be exploited to obtain a more realistic assessment of the forecasting error. In order to further validate the MCMC approach, the posterior distribution of the Italian electricity price volatility is explored for different maturities and compared with the corresponding maximum likelihood estimates.     

Monge’s method for intermediate integrals

In this paper we will present a framework of solving a second order differential equation using a solvable first order equation. Such a first order equation is called an intermediate integral. Illustrative examples are used to highlight the proposed algorithm.     

Estimating linear functionals of a sparse family of Poisson means

Assume that we observe a sample of size n composed of p-dimensional signals, each signal having independent entries drawn from a scaled Poisson distribution with an unknown intensity. We are interested in estimating the sum of the n unknown intensity vectors, under the assumption that most of them coincide with a given “background” signal. The number s of p-dimensional signals different from the background signal plays the role of sparsity and the goal is to leverage this sparsity assumption in order to improve the quality of estimation as compared to the naive estimator that computes the sum of the observed signals. We first introduce the group hard thresholding estimator and analyze its mean squared error measured by the squared Euclidean norm. We establish a nonasymptotic upper bound showing that the risk is at most of the order of \(\sigma ^2(sp+s^2\sqrt{p}\log ^{3/2}(np))\). We then establish lower bounds on the minimax risk over a properly defined class of collections of s-sparse signals. These lower bounds match with the upper bound, up to logarithmic terms, when the dimension p is fixed or of larger order than \(s^2\). In the case where the dimension p increases but remains of smaller order than \(s^2\), our results show a gap between the lower and the upper bounds, which can be up to order \(\sqrt{p}\).