Chiral liquid chromatography resolution and stereoselective pharmacokinetic study of the enantiomers of a novel anticonvulsant, N-(4-chlorophenyl)-1-(4-pyridyl)ethylamine, in rats

A selective chiral high performance liquid chromatographic (HPLC) method was developed and validated to separate and quantify the enantiomers of a novel anticonvulsant agent, N-(4-chlorophenyl)-1-(4-pyridyl)ethylamine (AAP-Cl), in rat plasma. After extraction of the plasma samples with ethyl acetate, the separation was accomplished by an HPLC system consisting of a Chirex chiral column (250 mm x 4.6 mm i.d.) and a mobile phase of hexane:ethanol:tetrahydrofuran (280:20:40 (v/v)) containing trifluroacetic acid (0.3% (v/v)) and triethylamine (0.018% (v/v)) at a flow rate of 0.8 ml/min with UV detection. Male Sprague-Dawley rats were given (+)-AAP-Cl (10 and 20 mg/kg), (-)-AAP-Cl (10 mg/kg) or the racemic mixture (20 mg/kg) by i.v. bolus injection and serial blood samples were collected at different times after drug administration. (+)-AAP-Cl and (-)-AAP-Cl were separated with a resolution factor, Rs, of at least 1.4, and a separation factor, alpha, greater than 1.09. Linear calibration curves were obtained over the concentration range of 0.5-30 microg/ml in plasma for both (+)-AAP-Cl and (-)-AAP-Cl (R2 > or = 0.996) with a limit of quantitation of 100 ng/ml and the recovery was greater than 80% for both enantiomers. The accuracy and precision for both enantiomers ranged from 96 to 102% (+/-0.2-7%) at upper and lower concentrations. The plasma concentration-time profiles of the enantiomers of AAP-Cl were best described by a two-compartment open model with a mean terminal half-life of about 5h, volume of distribution at steady state of 3 l/kg and clearance of about 0.6l/(hkg) in rats. There was no significant difference between the pharmacokinetic parameters of (+)-AAP-Cl and (-)-AAP-Cl, suggesting that the disposition of AAP-Cl in rats is not enantioselective. In addition, no chiral inversion of (+)-AAP-Cl to (-)-AAP-Cl or vice versa was observed. The results of this investigation have shed some light on the mechanism of action and disposition of AAP-Cl in rats.     

Survival of Male Patients with Incontinentia Pigmenti Carrying a Lethal Mutation Can Be Explained by Somatic Mosaicism or Klinefelter Syndrome

Incontinentia pigmenti (IP), or "Bloch-Sulzberger syndrome," is an X-linked dominant disorder characterized by abnormalities of skin, teeth, hair, and eyes; skewed X-inactivation; and recurrent miscarriages of male fetuses. IP results from mutations in the gene for NF-kappaB essential modulator (NEMO), with deletion of exons 4-10 of NEMO accounting for >80% of new mutations. Male fetuses inheriting this mutation and other "null" mutations of NEMO usually die in utero. Less deleterious mutations can result in survival of males subjects, but with ectodermal dysplasia and immunodeficiency. Male patients with skin, dental, and ocular abnormalities typical of those seen in female patients with IP (without immunodeficiency) are rare. We investigated four male patients with clinical hallmarks of IP. All four were found to carry the deletion normally associated with male lethality in utero. Survival in one patient is explained by a 47,XXY karyotype and skewed X inactivation. Three other patients possess a normal 46,XY karyotype. We demonstrate that these patients have both wild-type and deleted copies of the NEMO gene and are therefore mosaic for the common mutation. Therefore, the repeat-mediated rearrangement leading to the common deletion does not require meiotic division. Hypomorphic alleles, a 47,XXY karyotype, and somatic mosaicism therefore represent three mechanisms for survival of males carrying a NEMO mutation.     

The European carbon balance. Part 3: forests

We present a new synthesis, based on a suite of complementary approaches, of the primary production and carbon sink in forests of the 25 member states of the European Union (EU‐25) during 1990–2005. Upscaled terrestrial observations and model‐based approaches agree within 25% on the mean net primary production (NPP) of forests, i.e. 520±75 g C m^?2 yr^?1 over a forest area of 1.32 × 10⁶ km² to 1.55 × 10⁶ km² (EU‐25). New estimates of the mean long‐term carbon forest sink (net biome production, NBP) of EU‐25 forests amounts 75±20 g C m^?2 yr^?1. The ratio of NBP to NPP is 0.15±0.05. Estimates of the fate of the carbon inputs via NPP in wood harvests, forest fires, losses to lakes and rivers and heterotrophic respiration remain uncertain, which explains the considerable uncertainty of NBP. Inventory‐based assessments and assumptions suggest that 29±15% of the NBP (i.e., 22 g C m^?2 yr^?1) is sequestered in the forest soil, but large uncertainty remains concerning the drivers and future of the soil organic carbon. The remaining 71±15% of the NBP (i.e., 53 g C m^?2 yr^?1) is realized as woody biomass increments. In the EU‐25, the relatively large forest NBP is thought to be the result of a sustained difference between NPP, which increased during the past decades, and carbon losses primarily by harvest and heterotrophic respiration, which increased less over the same period.     

Nucleotide sequence of the genes for tryptophan synthase in Pseudomonas aeruginosa

We have determined the DNA sequence of the two adjacent genes for the alpha and beta chains of tryptophan synthase in Pseudomonas aeruginosa, along with 34 5'-flanking and 799 3'-flanking base pairs. The gene order is trpBA as predicted from earlier genetic studies, and the two cistrons overlap by 4 bp; a ribosome binding site for the second gene is evident in the coding sequence of the first gene. We have also determined the location of three large deletions eliminating portions of each gene. A detailed comparison of the deduced P. aeruginosa amino acid sequence with those published for E. coli, Bacillus subtilis, and Saccharomyces cerevisiae shows much similarity throughout the beta and most of the alpha subunit. Most of the residues implicated by chemical modification or mutation as being critical for enzymatic activity are conserved, along with many others, suggesting that three-dimensional structure has remained largely constant during evolution. We also report the construction of a recombinant plasmid that overproduces a slightly modified alpha subunit from P. aeruginosa that can form a functionally effective multimer with normal E. coli beta 2 subunit in vivo.      

Potent inhibition of retinoic acid metabolism enzyme(s) by novel azolyl retinoids

Novel (+/-)-4-azolyl retinoic acid analogues 4, 5, 7 and 8 have been designed and synthesized and have been shown to be powerful inhibitors of hamster microsomal all-trans-retinoic acid 4-hydroxylase enzyme(s). (+/-)-4-(1H-Imidazol-1-yl)retinoic acid (4) is the most potent inhibitor of this enzyme reported to date.     

Pharmacokinetic profile of 3beta-hydroxy-17-(1H-1,2,3-triazol-1-yl)androsta-5,16-diene (VN/87-1), a potent androgen synthesis inhibitor, in mice

The objective of this study was to assess the pharmacokinetics and bioavailability of 3beta-hydroxy-17-(1H-1,2,3-triazol-1-yl)androsta-5,16-diene (VN/87-1) in normal male mice and in SCID mice bearing human LNCaP tumor xenografts. VN/87-1 is a novel potent steroidal inhibitor of human testicular 17-alpha-hydroxylase/C(17,20)-lyase. The steroid also shows anti-androgenic activity and inhibits the growth of human prostate cancer cell lines (LNCaP) in vitro and in vivo. Male Balb/c mice were given a single oral, subcutaneous (s.c.) or intravenous (i.v.) bolus dose of VN/87-1 (25, 50 or 100 mg/kg). Male SCID mice bearing LNCaP tumor xenografts were injected with a single s.c. dose of VN/87-1 (50 mg/kg). The animals were sacrificed at various times up to 24 h after drug administration and blood was collected. The plasma samples were prepared and analyzed by a reversed phase HPLC system equipped with a diode array detector. A non-compartmental pharmacokinetic approach was used to evaluate the plasma level versus time data. Following i.v. administration of VN/87-1, the plasma levels declined exponentially with an elimination half-life of 1.2+/-0.03 h. The absolute bioavailability of the 50 mg/kg dose after oral or s.c. administration was 12.08+/-2 or 57.2+/-4.5%, respectively. VN/87-1 is a high clearance (5.0+/-1.3 l/h per kg) compound in mice and its volume of distribution was relatively large (6.5+/-1.2 l/kg). The pharmacokinetic parameters of VN/87-1 were not significantly altered in SCID mice bearing human LNCaP tumor xenografts. VN/87-1 is well absorbed from the subcutaneous site compared with absorption from the gastrointestinal tract and shows linear kinetics at doses up to 100 mg/kg.     

Water quality assessment of the Siluko River,southern Nigeria

The water quality of the Siluko River, Edo State, Nigeria was investigated from March to August 2015 to determine its suitability for drinking and usage for domestic purposes. Water samples collected from three stations were tested for thirteen physico-chemical parameters using standard analytical procedures. Temperature, phosphate and chloride were significantly different across the three stations. All other parameters, with the exception of turbidity, dissolved oxygen and phosphate, were within the permissible limits recommended by the Nigerian Standard for Drinking Water Quality (NSDWQ) and World Health Organization (WHO). Water Quality Index (WQI) values ranged from 11.24 to 16.15, indicating excellent water quality. While the quality of the water from the Siluko River is suitable for drinking and domestic usage, to prevent future deterioration of the water, it is recommended that the regulating authorities monitor effluents discharged into the river from human activities.     

Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta)

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.