Experimental intensity patterns obtained from a 2D shearing interferometer with adaptable sensitivity

The interferometric intensity patterns from a 2D shearing interferometer are shown and discussed. The intensity patterns can be obtained in two different approaches incorporating differential and extended wavefront controlled displacements. The reliable directional sensitivity of this interferometer allows the optimization of the measurement parameters to estimate the wavefront of the intensity patterns by regularization techniques.     

Effects of tributyltin(IV) chloride on the gametes and fertilization of Ascidia malaca (Ascidiacea: Tunicata)

Ascidia malaca gametes before fertilization incubated in 10^?5 or 10^?7 M solutions of tributyltin(IV) chloride, TBTCl, for 3 h appear highly damaged under transmission electron microscopy observation. Also, the fertilization process is affected by the compound: the damaged spermatozoa are present in the vitelline coat and the egg does not cleave. An increase of microbodies, structurally similar to peroxisomes, have been detected in the egg peripheral cytoplasm, probably in relation to their role in alleviating damage to some cellular components. The results have shown that the reproduction of ascidians under unfavourable environmental conditions is prevented. Copyright © 2003 John Wiley & Sons, Ltd.     

High-performance liquid chromatography-electrospray ionization mass spectrometry and multiple mass spectrometry studies of hyperforin degradation products

The alcoholic extract of the aerial parts of Hypericum perforatum L. finds wide application because of its antidepressant activity. The extract contains a number of constituents with documented biological activity including chlorogenic acid, a broad range of flavonoids, naphthodianthrones and phloroglucinols. Hyperforin and adhyperforin are the major phloroglucinol constituents found in the lipophilic fraction of the extracts. Since the stability of hyperforin has been shown to be limited, an investigation of the hyperforin degradation products using HPLC-electrospray ionization mass spectrometry and multiple mass spectrometry was undertaken.     

Harmonic oscillator tensors in contact transformation theory

The application of contact transformation theory to the perturbed harmonic oscillator is reexamined in the light of the harmonic oscillator tensors previously presented. It is found that the recasting of the formalism of this problem in terms of harmonic oscillator tensors results in great simplifications, most of which stem from the introduction of the additional algebraic quantum numbers (l, m). The order of magnitude of each fragment of the Hamiltonian is easily recognizable, and the diagonal and nondiagonal parts contained therein are readily identifiable. The determination of the contact transformation operator is reduced to a simple formula. First, an analysis is made for a single mode of vibration, and it is subsequently extended to a multimode case. The perturbed diatomic vibrator is presented as an example.     

(Z)-3-p-tolylsulfinylacrylonitrile as a chiral dienophile: diels-alder reactions with furan and acyclic dienes

The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles.     

High-performance liquid chromatographic determination of acetone in blood and urine in the clinical diagnostic laboratory.

A method for the determination of acetone in plasma or urine by high-performance liquid chromatography (HPLC) was developed. Plasma specimens are deproteinized with acetonitrile (1:1, v/v) 2,4-dinitrophenylhydrazine (DNPH) is added to the supernatant or to filtered urine samples, similarly treated with acetonitrile (2:1, v/v) to prevent crystallization of the synthesized phenylhydrazone. An aliquot (20 microliters) of the reaction mixture was subjected to HPLC at ambient temperature using a reversed-phase Pecosphere 3 x 3 C18 column with acetonitrile-water (45:55, v/v) as eluent at a flow-rate of 1 ml/min and detection at 365 nm. Hydroxyacetone and acetoacetate phenylhydrazone derivatives do not interfere. The identification of acetone by its retention time was confirmed by comparison with a laboratory-synthesized acetone DNPH derivative. The concentration of acetone, eluted within 3 min, was determined by the peak-height method. The detection limit was 0.034 mmol/l; the relative standard deviations were less than 5% within run (n = 20) and less than 10% between run (n = 20).     

Insights on the Modulation of SIRT5 Activity: A Challenging Balance

SIRT5 is a member of the Sirtuin family, a class of deacetylating enzymes consisting of seven isoforms, involved in the regulation of several processes, including gene expression, metabolism, stress response, and aging. Considering that the anomalous activity of SIRT5 is linked to many pathological conditions, we present herein an overview of the most interesting modulators, with the aim of contributing to further development in this field.