Separation of a group of N-phenylpyrazole derivatives by micellar electrokinetic chromatography: application to the determination of solute-micelle association constants and estimation of the hydrophobicity

Micellar electrokinetic chromatography (MEKC) was applied to the separation of a group of N-phenylpyrazole derivatives. Sodium dodecyl sulfate (SDS) as micellar system and 2-(N-cyclohexylamino)ethanesulfonic acid (CHES) as separation buffer (pH 10) were employed in the absence and presence of different percentages of medium chain alcohols (n-propanol or n-butanol). The separation of multicomponent mixtures of the solutes studied enabled the rapid determination of their retention factors which, in turn, allowed the study of the separation selectivity of compounds and the determination of their solute-micelle association constants (from the linear variation of the retention factors as a function of the total surfactant concentration in the separation buffer). Separation selectivity was studied according to the elution range and number of solutes separated in all the electrolyte solutions employed (45 micellar phases). The effect of the buffer concentration (0.05, 0.08 and 0.10 M), the alcohol nature (n-propanol or n-butanol) and the alcohol percentage (1, 3 or 5%) of the values obtained for the solute-micelle association constants was also studied. The best separation (12 solutes) was performed when a 0.08 M CHES buffer, pH 10, 0.02 M SDS modified by 5% n-butanol was used. The possibilities of using MEKC for evaluating the hydrophobicity of compounds was investigated through the study of the correlation between the logarithm of the retention factors of N-phenylpyrazole derivatives and their logarithm of the octanol-water distribution coefficients estimated by high performance liquid chromatography (HPLC).

[Client categorization: a tool to assess nursing workload]

BACKGROUND

Client categorization is a management tool that allows an objective and structured assessment of the care demands imposed by patients and nursing workloads.

AIM

To characterize the need for direct nursing care of patients admitted to a university hospital.

PATIENTS AND METHODS

During two months, all patients admitted to intensive, intermediate care units and general services were categorized, their need for nursing care and the time invested by nurses in their care was registered. All patients were classified as maximal, high, median or low risk and as independent, totally or partially dependent on nursing care. Considering four degrees of risk and three degrees of dependency, 12 categories of patients were defined.

RESULTS

Patients admitted to intensive care units were of maximal risk and totally dependent and required 1 nurse per 2.2 patients. Those admitted in intermediate care units required 1 nurse per 3.8 patients and those in general services, 1 nurse per 11.5 patients.

CONCLUSIONS

Client categorization is a reproducible method that determines a standard measuring unit to define nursing needs. This allows the comparison of workloads between different services within a hospital or between hospitals.

Accumulation of mercury in edible macrofungi: influence of some factors

The levels of mercury in terrestrial ecosystems are generally very low, but the strong accumulation in some species of macrofungi is an exception from this rule. Mercury contents of 41 samples of edible mushrooms fruiting bodies representing eight species (six wild and two cultivated) were determined by an anodic stripping voltammetric technique (ASV) using a gold disc as the working electrode. Wild fungi were collected in unpolluted and polluted areas in the Province of Lugo (NW Spain). Influence of some factors (ecology, species, traffic pollution, and morphological portion) and the importance of mushrooms as a dietary source of mercury have been studied. Wild saprophytic species showed higher levels (ppm DW) than mycorrhizals species, with the exception of Boletus pinicola. There were significant differences according to the species analyzed (p < 0.001), the highest average content of mercury was found in Boletus pinicola (7.37 ppm DW), and the range was 0.35-33.07 ppm DW for hymenophore and 0.18-20.30 ppm DW for the rest of the fruit body. The cultivated species accumulated lower than wild species because the mean life is shorter. The traffic pollution factor did not show significant differences, so mushrooms are not realiable bioindicators of traffic pollution by mercury. Hymenophore was always the morphological portion that contained the highest mercury levels (p < 0.05), and the mean ratio of hymenophore/rest of the fruit body was 2.13. The mercury concentrations were compared to literature data and levels set by legislation, and the contribution of mushrooms to the weekly intake of mercury per person was evaluated. The possible health risk for people is pointed out.

Determination of orbifloxacin in rabbit plasma by high-performance liquid chromatography with fluorescence detection

A simple and sensitive high-performance liquid chromatography method is developed for the determination of orbifloxacin (ORB) in rabbit plasma. Sample preparations are carried out by adding phosphate buffer (pH 7.4, 0.1 M) and extracting with trichloromethane. ORB and the internal standard, norfloxacin (NOR), are separated on a reversed-phase column using an aqueous phosphate buffer-acetonitrile (80:20, v/v) mobile phase. The concentrations of ORB and NOR eluting from the column with retention times of 2.16 and 3.09 min, respectively, are monitored by fluorescence detection at 338 (excitation) and 425 nm (emission). The method is shown to be linear from 4 to 1500 ng/mL (regression coefficient r2 = 0.999). The quantitation and detection limits are 4 and 9 ng/mL, respectively. Mean recovery is determined as 92% by the analysis of plasma standards containing 150, 750, and 1500 ng/mL. Inter- and intra-assay precisions were 4 and 3%, respectively.

Transcription factor AP-2 activity is modulated by protein kinase A-mediated phosphorylation

We recently reported that APOE promoter activity is stimulated by cAMP, this effect being mediated by factor AP-2 [Garcia et al. (1996) J. Neurosci. 16, 7550-7556]. Here, we study whether cAMP-induced phosphorylation modulates the activity of AP-2. Recombinant AP-2 was phosphorylated in vitro by protein kinase A (PKA) at Ser239. Mutation of Ser239 to Ala abolished in vitro phosphorylation of AP-2 by PKA, but not the DNA binding activity of AP-2. Cotransfection studies showed that PKA stimulated the effect of AP-2 on the APOE promoter, but not that of the S239A mutant. Therefore, cAMP may modulate AP-2 activity by PKA-induced phosphorylation of this factor.

High-sensitivity analysis and sequencing of peptides and proteins by quadrupole ion trap mass spectrometry

This paper describes experience with the commercially available LCQ quadrupole ion trap mass spectrometer applied to the off-line analysis of peptides and proteins. The standard front end of the electrospray probe was replaced with a micromanipulator which, with the aid of a magnifying device, allowed the use of a variety of miniaturized spraying interfaces. The low sample consumption and extended analysis times of these devices were ideally suitable to obtain improved results in terms of sensitivity and mass accuracy. This needed a careful optimization of the number of ions stored inside the trap (ion target parameter) and required spectrum averaging of many scans. A method is presented for the mathematical fitting of ZoomScan spectra to theoretical isotopic distributions, which allowed the mass determination of large peptides with more accuracy than that achieved by conventional deconvolution algorithms. A very simple on-line desalting configuration is also described which needed no external micro-high-performance liquid chromatographic pumps, and can be easily mounted using the built-in syringe delivery system of the LCQ. This set-up allowed extended analysis times of 'in-gel' protein digests in subpicomole amounts. Finally, the multiple fragmentation capabilities of the ion trap were found to be extremely useful for the analysis of peptide modifications such as phosphorylation and for sequencing individual peptides from highly complex MHC-bound peptide pools.

Risk for Alzheimer's disease correlates with transcriptional activity of the APOE gene

While the straightepsilon4 allele of apolipoprotein E ( APOE, gene; ApoE, protein) is widely accepted as a major genetic risk factor for the late onset form of Alzheimer's disease (AD), recent evidence points to variations in ApoE levels as another important factor. We have previously reported that a common variant in the regulatory region of APOE (-491A) is associated with risk for late onset AD. In this report we analyze the association of another APOE promoter polymorphism (-427T/C) with AD in two case-control clinical samples and demonstrate a correlation between APOE promoter transcriptional activity and risk for AD. The association studies show that the allelic variant (-427C) and the haplotype [-491A-427C] of the APOE promoter are associated with increased risk for AD. Study of the transcriptional activity of the common haplotypes defined by combination of the -491 and -427 alleles indicated that the risk for late onset AD positively correlates with transcriptional activity of the APOE gene, suggesting that increases in the local expression of ApoE could be responsible for the association of APOE promoter polymorphism with AD.

Influence of some factors in toxicity and accumulation of cadmium from edible wild macrofungi in nw Spain

Cadmium content of 97 samples of some edible wild mushrooms, corresponding to 13 different species, was determined by graphite furnace atomic absorption spectrophotometry. Influence of some factors (species and ecology, morphological portion, and traffic pollution) and the importance of mushrooms as a dietary source of this heavy metal have been studied. Saprophite species showed higher levels than mycorrhizal ones (p < 0.001), with some exceptions such as Boletus and Amanita. The hymenophore was always the morphological portion which contained the highest cadmium levels (p < 0.001). Traffic pollution was not a significant factor for the cadmium accumulation in fungi. The samples of Agaricus macrosporus showed the highest mean levels (68.96 and 36.84 ppm dry matter (d. m.) for hymenophore and the rest of the fruit-body, respectively). The average cadmium content of the samples, with the exception of A. macrosporus, was 0.96 for hymenophore and 0.53 ppm d.m. for the rest of the fruit-body; and the range was between 0.18-4.32 and 0.10-1.91 ppm d.m. for hymenophore and the rest of the fruit-body. The concentration levels were compared to literature data and levels set by legislation, and the contribution of mushrooms to the weekly intake of cadmium per person was calculated. The possible health risk for the consumer is pointed out.

Lead content in edible wild mushrooms in northwest Spain as indicator of environmental contamination

Lead content was determined in wild growing mushrooms collected from two different areas in the Province of Lugo (NW Spain). It has been analyzed by graphite furnace atomic absorption spectrometry in 95 samples of 13 species (7 mycorrhizals and 6 saprophites). In an assessment of lead concentrations, the following factors have been considered: species and ecology, morphological portion, and traffic pollution. The average lead concentration of the samples was 1 ppm dry weight (dw). Saprophite species presented higher levels than mycorrhizal ones (< 1 ppm), Coprinus comatus reaching the maximum mean concentration with 2.06 and 2.79 ppm of dw in the hymenophore and the rest of the fruit body. Morphological portion, statistically, did not show significant difference between the two portions; however, Macrolepiota procera always presented lead high levels in the hymenophore in all samples. The effect due to traffic pollution has been specially observed in Coprinus comatus, presenting the highest concentration with values of 6.51 and 10.43 ppm, respectively, in samples collected in the city center. This species, as other researchers have indicated, could be considered as an indicator by lead contamination. The contribution of mushrooms to the weekly intake of lead was calculated and the possible health risk for the consumer is pointed out. These data are of great importance in view of toxicology and partly environmental protection.

Allelic polymorphisms in the transcriptional regulatory region of apolipoprotein E gene

In this work, we explored the existence of genetic variants within the apolipoprotein E gene transcriptional regulatory region, using a denaturing gradient gel electrophoresis screening of a region comprising nucleotides -1017 to +406. Upon a population study, three new polymorphic sites (-491, -427 and -219) and two mutations were found. Functional effects of the polymorphisms, assayed by transient transfection and electrophoretic mobility shift assays in a human hepatoma cell line, showed that polymorphisms at sites -491 and -219 of the APOE promoter produce variations in the transcriptional activity of the gene, most probably through differential binding of nuclear proteins.

A polymorphism in the regulatory region of APOE associated with risk for Alzheimer's dementia

The epsilon4 allele of the apolipoprotein E gene (APOE) has been associated with an increased risk of developing Alzheimer's disease (AD; refs 1,2). However, it is apparent that the APOEepsilon4 allele alone is neither necessary nor sufficient to cause the disease. We have recently found three new polymorphisms within the APOE transcriptional regulatory region (M.J.A. et al., manuscript submitted) and now establish an association between one of these polymorphisms (-491A/T) and dementia as observed in Alzheimer's disease, in two independent clinical populations. The results suggest that homozygosity of a common variant (-491A) is associated with increased risk for AD, and that this association is independent of APOEepsilon4 status. In vitro studies suggest that the -491A/T polymorphism may increase risk for AD by altering the level of ApoE protein expression.

Limited capacity of neonatal rabbits to eliminate enrofloxacin and ciprofloxacin

The pharmacokinetics of enrofloxacin (ENR) and ciprofloxacin (CIP) in newborn and young rabbits were studied. Rabbits of different ages (1-, 8-, 16-, and 30-day-old) were administered, by the intraperitoneal route (i.p.), a dose of 7.5 mg of either drug/kg. In 1-, 8-, and 16-day-old rabbits, blood samples were drawn by cardiac puncture, under light ether anaesthesia, at predetermined times after drug administration. In 30-day-old rabbits, serial blood samples were drawn through an arterial catheter. Plasma was immediately obtained and analysed using an HPLC method. ENR and CIP plasma protein binding was also determined. The plasma pharmacokinetic profiles of ENR and CIP obtained for 30-day-old rabbits agreed with those reported in the literature for healthy adult rabbits. Nevertheless, significant differences were observed for the body clearance, the slope of the terminal phase, the volume of distribution, and the area under the curve when compared with those for younger animals (1-, 8-, and 16-day-old rabbits), indicating a limited capacity of neonatal rabbits to eliminate ENR and CIP. No differences were found when we compared the calculated values for ENR or CIP plasma protein binding as a function of the postnatal age, indicating that development does not seem to alter the free fraction of these drugs in the rabbit. Taking into account that extensive placental and milk transfer has been reported for these drugs after administration to pregnant or nursing rabbits, a cautious, attitude regarding their use in these animals must be adopted.

Enhanced diltiazem deacetylase activity in pre-term and full-term rabbits compared with adult rabbits

The in vitro metabolic activity of the esterase responsible for the hydrolysis of diltiazem (DTZ) to its deacetylated metabolite (M1) was determined in an age-dependent fashion using the rabbit as an animal model. The presence of the enzyme in several tissues (liver, lung, small intestine, and brain) and in whole blood from pre-term and full-term fetuses, full-term newborns, yound and adult rabbits was examined. To this end, DTZ was spiked to 10,000-g tissue homogenates and whole blood to yield a final concentration of 1 microgram/ml. Serial samples were withdrawn from the incubation medium up to 240 min and assayed for DTZ and M1 concentration. In all tissues examined there was a net production of M1. Chemical breakdown and stability studies confirmed the metabolic origin of the M1 formed throughout the incubation. In pre-term fetuses (25 days of gestation) the brain was found to be the most active tissue in eliminating DTZ (brain > liver > lung > small intestine). This trend changed in young and adult rabbits (lung = brain > liver > small intestine). Although an important age-dependent DTZ deacetylase activity was observed in blood, it was not included in the comparison between organs because of the unequal composition of the incubation medium. In conclusion, results showed that fetuses and newborn rabbits have a similar, and in some instances higher, DTZ deacetylase activity to that in adults (p < 0.05). In vitro findings were further confirmed by in vivo experiments.

[Serous otitis media. Comparative study of carbinoxamine- pseudoephedrine vs astemizole-pseudoephedrine]

They were studied 48 children of 3 to 8 years old, of two sex (30 male and 18 female), that attended the external service of otolaryngology of the Hospital of the ISSSTE of Nuevo Laredo, Tamaulipas (Mexico) and the private practice of the Allergy Clinic and Otolaringol in Nuevo Laredo, Tamaulipas, of the month of November of 1995 to April of 1996. Some of the side effects observed in the patients treated in the group A (carbinoxamine-P) were: mild sedation and in some instances hyperexcitability and irritability. However, it was not necessary to discontinue the medication or to modify the dose. In the group B (astemizole-P) was observed only excitement and irritability in some instances by hypersensitivity to the pseudoephedrine. It is very important to consider that the adequate and timely treatment in a patient with otitis serous media will permit to avoid sequels that they can cause, in the long run, a meaningful impact in the language and intellectual development of the child.

On the mechanism of action of ethodin in inducing myometrium contractions

1. Ethodin (Rivanol, 6,9-diamino-2-oxyethyl acridine lactate), has been described as an effective drug to induce uterine contractions similar to those in a physiologic labor in still-birth with uterine inertia. We investigate the mechanisms involved in the effect of this compound in contracting the smooth-muscle cells of the myometrium to improve our understanding of the processes involved in the onset of labor. 2. We conclude that the contractile effect of ethodin is mediated through the activation of uterine mast cells that release mediators able to contract the myometrium.

CYP2D6, NAT2 and CYP2E1 genetic polymorphisms in nonagenarians

BACKGROUND

enzymatic polymorphisms affecting the metabolic disposition of xenobiotics may modulate the rate of activation or deactivation of carcinogens and other toxic environmental chemicals. Hence, these polymorphisms may influence the risk of suffering some types of cancer and other degenerative diseases that are incompatible with extreme longevity.

AIMS

to establish the distribution of three well known enzymatic polymorphisms that affect the CYP2D6, NAT-2 and CYP2E1 genes and the activity of their enzymatic gene products, involved in the disposition of many xenobiotics, in a group of nonagenarians and in much younger controls.

PATIENTS

the three genotypes were determined in 41 nonagenarians (10 males, mean age 92.2 years, range 90-98) free of known malignancies or neurodegenerative diseases. The control groups comprised 217 healthy volunteers (128 males, mean age 36.3 years; SD, 12.7) for the CYP2D6 and NAT2 genotypes and 137 (116 males, mean age 32 years; SD, 18.8) for the CYP2E1 genotype.

METHODS

after extraction of DNA from white blood cells, polymerase chain reaction and restriction fragment polymorphism methods were used to identify the allelic variants of the three genotypes.

RESULTS

we found no qualitative or quantitative difference in the mutations underlying the three genetic polymorphisms studied, nor in the expected enzymatic phenotypes. Instead, a close parallelism exists between advanced age and younger groups.

CONCLUSION

longevity does not seem to be related to any special configuration of these three polymorphic traits. Comparisons with younger controls may be adequate when studying the distribution of these polymorphisms in diseases affecting old people. No genetically determined differences in the activation of drugs metabolized by these enzymes are to be expected in very old people.

Transcription factor AP-2 regulates human apolipoprotein E gene expression in astrocytoma cells

Apolipoprotein E (apoE), one of the major plasma lipoproteins, also is expressed in a variety of cell types, including the glial cells of the nervous system. apoE is involved in processes of degeneration and regeneration after nerve lesions as well as in the pathogenesis of Alzheimer's disease (AD). Glial synthesis of apoE is activated in response to injury both in the peripheral and central nervous system. We now report that the activity of the proximal apoE promoter in astrocytes is upregulated by cAMP and retinoic acid, which act synergistically. Sequence analysis of the apoE promoter indicated the presence of several AP-2 consensus sequences that could mediate the stimulatory effect of cAMP and retinoic acid. The possible functional role of AP-2 was examined by cotransfection of AP-2-deficient HepG2 cells with an apoE promoter construct and a human AP-2 expression construct. Cotransfection with AP-2 significantly elevated apoE promoter activity. DNase I footprinting technique revealed the existence of two binding sites for recombinant AP-2 in regions from -48 to -74 and from -107 to -135 of the apoE promoter. Mutations in these regions markedly impaired the trans-stimulatory effect of AP-2. These results indicate the existence of functional AP-2 sites in the promoter region of apoE that could contribute to the complex regulation of this gene in developmental, degenerative, and regenerative processess of the nervous system.

Deacetylation of diltiazem by several rabbit tissues

PURPOSE

Diltiazem (DTZ) undergoes extensive metabolism yielding several metabolites, some of which retain a certain degree of pharmacological activity. N-demethylating activity has been detected mainly in the liver. Nevertheless, the organs involved in the formation of the deacetylated metabolite of DTZ (M1) have not been fully elucidated. In order to address this issue, we have carried out in vitro studies using the blood, lung, brain, small intestine, and liver as enzyme sources.

METHODS

DTZ (1,000 ng/ml) was incubated in 10,000 x g supernatant homogenates of selected tissues or in whole blood for 240 minutes at 37 degrees C. Multiple samples were withdrawn, and DTZ and its metabolite M1 were assayed by HPLC.

RESULTS

The apparent degradation rate constant of DTZ was in the rank order blood > lung > brain > liver > small intestine. This trend can also be observed for the AUC and for the percentage of DTZ metabolized. In all the tissue homogenates examined there was a net production of the deacetylated metabolite. The M1 metabolite was also detected in the blood (500 ng/ml after 240 minutes of incubation).

CONCLUSIONS

The widespread distribution of the DTZ deacetylase activity described in this study suggests that extrahepatic metabolism of DTZ to M1 may play a relevant role in the overall pharmacokinetics of DTZ.