[Direct chiral resolution with CD-MEKC of enantiomers of crisene trans-1,2 diol; activation in vitro of crisene in the S9 rat liver microsomal fraction].
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Animals↗
Biomedical subjects
C Desiderio
Publications and source records attributed to C Desiderio.
Cyclodextrin modified micellar electrokinetic chromatography for the chiral direct resolution of (+), (-)-trans-1,2-dihydrodiol metabolite of chrysene in vitro activated by rat liver microsome S9 fraction.
A gamma-cyclodextrin (gamma-CD) modified electrokinetic micellar capillary chromatography (MEKC) method was used for the enantiomer separation of a racemic trans-1,2-dihydro-1,2-dihydroxy-chrysene (chry-trans-1,2-diOH) mixture. The chiral resolution was strongly influenced by several important parameters: surfactant concentration and addition of organic modifier to the background electrolyte (BGE). An optimized electrophoretic system was used, consisting of the following conditions: 25 mM phosphate buffer, pH 7.8, 50 mM sodium dodecyl sulfate, 20 mM gamma-CD, 7.4% v/v 2-propanol as BGE; the applied voltage, 18 kV, corresponded to 37 microA at a constant temperature of 25 degrees C. This electrophoretic method was applied for monitoring the chry-trans-1,2-diOH enantiomer formation in a real sample, obtained from in vitro metabolic activation of chrysene by phenobarbital-beta-naphthoflavone-induced rat microsomes. The (+) and (-) enantiomers were identified by the racemate and the single enantiomer standard addition method and by spectra comparison with the synthetic compound. Under the experimental conditions used for chrysene activation, the (+) optical isomer was the prevailing form. The CD-MEKC system showed high reproducibility and selectivity, allowing a fast and interference-free analysis even of the in vitro metabolic sample extract, without any pretreatment.
Animals↗
[Stereoselective analysis of pharmaceutical compounds in biological fluids with capillary electrophoresis].
Biological fluids drugs analysis are important to investigate the pharmacokinetic and pharmacodynamic of the subministered compounds for the comprehension of their behaviour and bioavailability. Many pharmaceutical preparations contain a chiral molecule as active compound often as racemic mixture of the two enantiomers of which only one exhibits pharmacological effect, the other enantiomer being inactive or responsible of toxicological effects. In fact two enantiomers with almost identical physical and chemical properties can exhibit a different behaviour in an highly stereoselective environment as the human body. With respect to the analytical methods in use for chiral separation Capillary Electrophoresis shows high efficiency and resolution together with feasibility, low costs and very short analysis time. CE and MEKC have been used for enantiomers resolution of antihypertensive and anticoagulant drugs in body fluids. By cyclodextrin modified MECK the separation of mephenytoin and 4-hydroxymephenytoin metabolite in urine samples has been performed in order to identify different phenotypes in the oxidative metabolising ability in man.
Animals↗
Screening for hydroxylation and acetylation polymorphisms in man via simultaneous analysis of urinary metabolites of mephenytoin, dextromethorphan and caffeine by capillary electrophoretic procedures.
Phenotypes for hydroxylation can be predicted by using mephenytoin and dextromethorphan as substrates, whereas phenotypes for acetylation can be determined with caffeine as probe drug. After single-dose administration of one of these drugs, of two of them simultaneously, or of the three drugs together, the major urinary metabolites (4-hydroxymephenytoin; dextrorphan, 3-methoxymorphinan, 3-hydroxymorphinan; 5-acetylamino-6-amino-3-methyluracil as decomposition product of 5-acetylamino-6-formylamino-3-methyluracil, 1-methylxanthine, respectively) of these substrates were analyzed by capillary electrophoretic techniques. No sample pretreatment other than enzymatic hydrolysis of the conjugated compounds was applied. Assays based on micellar electrokinetic capillary chromatography are shown to allow simultaneous and unambiguous phenotyping with mephenytoin and dextromethorphan or mephenytoin and caffeine. Simultaneous screening for all three polymorphisms with a single injection of a hydrolyzed urine is shown to be possible via use of multiwavelength absorption detection only. Phenotypes determined by electrokinetic capillary techniques are shown to agree with those obtained by analysis with customary assays based on high-performance liquid chromatography.
Acetylation↗
Separation of alpha-hydroxy acid enantiomers by high performance capillary electrophoresis using copper(II)-L-amino acid and copper(II)-aspartame complexes as chiral selectors in the background electrolyte.
Optical isomers of some alpha-hydroxy acids, namely 2-, 3-phenyllactic acid, mandelic, p-hydroxy-, m-hydroxy and 3,4-di-hydroxymandelic acid, were separated by means of capillary zone electrophoresis in free solution, using copper (II) complexes with L-amino acid or aspartame ligands in the background electrolyte. The concentration and the pH dependence of the enantiomer separations have been studied in the cases of different chiral ligands and/or analytes. With the use of L-proline as ligand only the optical isomers of 3-phenyllactic acid were resolvable, whereas using L-hydroxyproline the D and L forms of all compounds, except for 2-phenyllactic acid, were separated. Better results were obtained with aspartame as chiral ligand.
Amino Acids↗
Analysis of mephenytoin, 4-hydroxymephenytoin and 4-hydroxyphenytoin enantiomers in human urine by cyclodextrin micellar electrokinetic capillary chromatography: simple determination of a hydroxylation polymorphism in man.
Using cyclodextrin micellar electrokinetic capillary chromatography (CD-MECC), baseline separation of mephenytoin, 4-hydroxymephenytoin and 4-hydroxyphenytoin enantiomers in urine was effected with beta-cyclodextrin. After single-dose administration of 100 mg of racemic mephenytoin, the 0-8 h urine was collected, and enzymatically hydrolyzed urine specimens were applied. For extensive metabolizers, a single peak for 4-hydroxymephenytoin was detected corresponding to the S-enantiomer. This peak was either very small or undetectable in samples of poor metabolizers. Typically, mephenytoin could not be detected in these samples. However, application of undeglucuronidated extracts revealed the presence of free S-4-hydroxymephenytoin and R,S-mephenytoin and thus permitted phenotyping via both the urinary S:R enantiomeric ratio of mephenytoin and the hydroxylated metabolite. Application of enzymatically hydrolyzed and extracted urines after phenytoin administration (100 mg; 0-8 h urine collection) revealed the presence of S-4-hydroxyphenytoin. Thus, CD- MECC is shown to be a simple and attractive approach for (i) the confirmation of the stereoselectivity of the aromatic hydroxylation of mephenytoin and phenytoin, (ii) the simple and rapid differentiation between extensive and poor metabolizers for mephenytoin, and (iii) assessment of compliance.
Buffers↗
Capillary electrophoresis quantitation of l-L-folinic acid in the presence of its inactive d-L-form.
The diastereomers d-L and l-L-folinic acid were separated by capillary electrophoresis, using heptakis (2,3-di-O-methyl)-beta-cyclodextrin as a chiral active component in the background electrolyte. The method proved suitable for the quantitation of these compounds in one commercial pharmaceutical preparation.
Capillary Action↗
Micellar electrokinetic chromatographic study of hydroquinone and some of its ethers. Determination of hydroquinone in skin-toning cream.
The separation of hydroquinone and some of its ether derivatives was studied by micellar electrokinetic chromatography with sodium dodecyl sulphate as an anionic surfactant in the background electrolyte. The optimized method was used for the determination of hydroquinone in a sample of skin-toning cream. On-column detection at 254 nm with caffeine as an internal standard gave good quantitative results.
Caffeine↗
Total gastrectomy: nutritional status after different reconstruction techniques. An experimental study.
The authors report their experimental studies on early nutritional changes in 30 gastrectomized rats where intestinal continuity was restored by three different reconstruction methods, i.e., exclusion of the duodenum from alimentary transit (Sweet-Allen method), or duodenal recanalization (Longmire method) or double duodenal and jejunal recanalization (Moricca method). Ten sham operated rats were used as controls. Results showed that the group of rats which underwent Longmire's reconstruction presented better nutritional parameters (body weight gain, daily food intake, feeding efficiency, albuminemia) than the Moricca and Sweet-Allen reconstruction groups. These results became statistically significant when follow up was extended to 18 months by using an actuarial method. However, perioperative mortality rate was highest in the Longmire reconstruction group.
Anastomosis, Surgical↗
[Probable correlations ultrastructural anomalies of the central nervous system and hyperammonemia following portacaval anastomosis in rats].
The correlation between hyperammonemia, during porto-systemic encephalopathy, and brain's lesions in patients died for porto-systemic encephalopathy is not demonstrated. The aim of this study has been to try a demonstration. A histological study of the brain, cerebellum, brainstem, and spinal cord was made in 60 rats: in 40 rats 1, 3 and 6 months after portocaval shunt, and in 20 rats sham operated. The brain, cerebellum, brainsteam and spinal cord have been fixed with paraformaldehyde (4%) and then sectioned for optical and electronic microscopic study. Ammonemia was measured regularly in the 40 rats with portocaval shunt, all the rats have been hyperammonemia since 10 weeks, after this period in 4 rats ammonemia was normal. In 20 rats sham-operated ammonemia was always normal. One month after surgery electronic microscopy revealed changes in the astrocytes characterized by nuclear swelling and lobulation. Three months after surgery this lesion was increased. After six months most lesions were noted in the hyperammoniemic rats. No similar lesions were observed in control rats. These results suggest that hyperammonemia is responsible of nuclear changes in the astrocytes of the patients died from hepatic encephalopathy.
Ammonia↗
Acute neuropathological changes in the caudate nucleus caused by MPTP and methamphetamine: immunohistochemical studies.
Three days after the administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) or methamphetamine to mice, there is degeneration and disappearance of punctate tyrosine hydroxylase-containing synaptic endings in the caudate nucleus. The neuropil is occupied with longer, varicose, branching fibres, which appear to be preterminal fibres. An intense gliosis occurs. The sparsely-occurring glial cells, with profuse lightly-stained (by glial fibrillary acidic protein) processes which are primarily located near blood vessels, become transformed into more heavily-stained star-shaped cells with fewer but thicker processes. These cells are distributed throughout the caudate. Despite apparent differences in the mechanism by which MPTP and methamphetamine cause dopamine depletion, the neuropathological changes in the caudate induced by these substances are identical.
Animals↗
Behavioral stimulation of ovarian growth.
The present study was conducted to test the following hypothesis: male courtship induced egg-laying behavior in the female ring dove is mediated by the female's nest-coo display which feeds back to stimulate her ovarian system through the mechanisms of audio- and proprioceptive feedback. In Experiment I, females were exposed to 24 hr male courtship and then received playback of different nest-coos in the absence of their mates. All playback was effective in inducing the females to perform nest-coo displays, but none as effective as presence of the courting males. A specified level of the female's nest-coo display determined whether there would be changes in follicular diameter. The females which received no playback after 24 hr pairing with the male (control) did not show any change in the follicular diameter. In Experiment II, females were deafened by removal of cochleae and upon recovery paired with males. Half of those deafened females performed nest-coo displays and subsequently laid clutches. The others failed to perform the display and did not lay. We conclude that both proprioceptive feedback and audio-feedback must be involved to yield maximal stimulation of follicular growth by the female's nest-coo display.
Animals↗
[Evaluation of a new system for the simultaneous identification and antibiotic sensitivity testing of gram-negative bacilli by automation].
ABAC- IDENTIBIOGRAMMA II is a new system allowing the carry out of antimicrobial susceptibility testing on various bacterial groups and also the fully automatic simultaneous susceptibility testing and identification of Gram-negative bacilli (urinary and not). Particularly most species of Enterobacteriaceae and Aeromonas hydrophila, Acinetobacter sp., Pseudomonas sp. can be identified. This system has two important characteristics, due to a computerized program: that is the possibility of using sensitivity data as complement of the biochemical assays to obtain identification and the directions for use transmitted through the display. The validity of system and the reliability of its results have been verified.
Anti-Bacterial Agents↗
[A case of cancerized papillary adenoma of the Vaterian region].
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Adult↗
[Choice of criteria in the revision of the ABAC system for the determination of sensitivity to antibiotics].
The limitation of the ABAC system for the automated antibiotic sensitivity test is the fixed number of antibiotics to be assayed. This limit is partially overcome by the up-dating of ABAC disposables necessary both for bacterial infectious pathology (considerably various and dinamic) and bacterial resistance to antibiotics. Accordingly, research is constantly producing new antibiotics particularly in the beta-lactamine and aminoglycoside fields. In these groups new antibiotics must be found to substitute the old ones in the ABAC disposables, in particular in relation to Gram-negative bacteria (urinary or not). The preparation of a rotor for experimental use containing new antibiotics not present on the market is proposed to evaluate their validity through a rapid and standardized method.
Anti-Bacterial Agents↗
Atrazine and simazine determination in river water samples by micellar electrokinetic capillary chromatography.
A rapid and sensitive micellar electrokinetic capillary chromatography analytical method was used for the determination of chlorotriazine herbicides in river water samples. Several electrolyte systems in the pH range 7-10 were tested in order to optimize the separation. The two compounds were separated in less than 10 min and the determination limit was about 0.4 ppb for each herbicide. Recovery values of the method were in the range 80%-117%.
Atrazine↗
Enzyme activities of the lipid metabolism in subcellular fractions of the hypertrophying heart during adaptation to hypoxia.
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1-Acylglycerophosphocholine O-Acyltransferase↗
[Evaluation of a new system for simultaneous identification and antibiograms of enterobacteria from urine].
A new rotor for the ABAC system has been investigated that allows the main enterobacteria of urinary source to be identified (this is performed manually) and simultaneously the relative antibiogram (this is automatically carried out). The precision of this identification has been shown using control strains previously identified by three miniaturized kits: API 20 E, MICRO-ID and ENTEROPLATE. The accuracy of the ten identification tests present in the new "Identibiogramma" rotor has also been shown. Finally, the correspondence has been shown between the antibiogram performed with the automatized method and that with the KirbyBauer method. The data obtained evidence the validity of the new rotor and of the ABAC system.
Anti-Bacterial Agents↗