Pharmacological characterization of GSK1004723, a novel, long-acting antagonist at histamine H(1) and H(3) receptors.

BACKGROUND AND PURPOSE: Preclinical pharmacological characterization of GSK1004723, a novel, dual histamine H(1) and H(3) receptor antagonist. EXPERIMENTAL APPROACH: GSK1004723 was characterized in vitro and in vivo using methods that included radioligand binding, intracellular calcium mobilization, cAMP production, GTPγS binding, superfused human bronchus and guinea pig whole body plethysmography. KEY RESULTS: In cell membranes over-expressing human recombinant H(1) and H(3) receptors, GSK1004723 displayed high affinity, competitive binding (H(1) pKi = 10.2; H(3) pKi = 10.6). In addition, GSK1004723 demonstrated slow dissociation from both receptors with a t(1/2) of 1.2 and 1.5 h for H(1) and H(3) respectively. GSK1004723 specifically antagonized H(1) receptor mediated increases in intracellular calcium and H(3) receptor mediated increases in GTPγS binding. The antagonism exerted was retained after cell washing, consistent with slow dissociation from H(1) and H(3) receptors. Duration of action was further evaluated using superfused human bronchus preparations. GSK1004723 (100 nmol·L(-1) ) reversed an established contractile response to histamine. When GSK1004723 was removed from the perfusate, only 20% recovery of the histamine response was observed over 10 h. Moreover, 21 h post-exposure to GSK1004723 there remained almost complete antagonism of responses to histamine. In vivo pharmacology was studied in conscious guinea pigs in which nasal congestion induced by intranasal histamine was measured indirectly (plethysmography). GSK1004723 (0.1 and 1 mg·mL(-1) intranasal) antagonized the histamine-induced response with a duration of up to 72 h. CONCLUSIONS AND IMPLICATIONS: GSK1004723 is a potent and selective histamine H(1) and H(3) receptor antagonist with a long duration of action and represents a potential novel therapy for allergic rhinitis.

In vitro activity of gemifloxacin and contemporary oral antimicrobial agents against 27247 Gram-positive and Gram-negative aerobic isolates: a global surveillance study.

This study was a multi-centre, multi-country surveillance of 27247 Gram-positive and Gram-negative isolates collected from 131 study centres in 44 countries from 1997 to 2000. MICs of gemifloxacin were compared with penicillin, amoxicillin-clavulanic acid, cefuroxime, azithromycin, clarithromycin, trimethoprim-sulphamethoxazole, ciprofloxacin, grepafloxacin and levofloxacin by broth microdilution. Penicillin resistance in Streptococcus pneumoniae was extremely high in the Middle East (65.6%), Africa (64.0%) and Asia (60.4%) and lower in North America (40.3%), Europe (36.9%) and the South Pacific (31.8%). Macrolide resistance in S. pneumoniae was highest in Asia (51.7%) but varied widely between laboratories in Europe (26.0%), North America (21.6%), the Middle East (13.7%), the South Pacific (10.6%) and Africa (10.0%). All the study quinolones were highly active against penicillin-resistant and macrolide-resistant S. pneumoniae. Overall, gemifloxacin had the lowest MIC(90) at 0.06 mg/l with MICs 4-64-fold lower than ciprofloxacin, levofloxacin and grepafloxacin against S. pneumoniae. Gemifloxacin MICs were more potent than grepafloxacin > levoflaxacin > ciproflaxin against the Gram-positive aerobes and shared comparable Gram-negative activity with ciprofloxacin and levofloxacin.

Comparative in vitro potency of amoxycillin-clavulanic acid and four oral agents against recent North American clinical isolates from a global surveillance study.

The in vitro activity of amoxycillin-clavulanic acid was compared with four comparator oral antimicrobial agents; ampicillin, azithromycin, cefuroxime and trimethoprim-sulphamethoxazole against 4536 recent clinical isolates covering 29 species isolated in the US and Canada between 1997 and 1999. Based upon Minimum inhibitory concentrations (MICs), amoxycillin-clavulanic acid was the most active agent against many Gram-positive species and phenotypes including methicillin susceptible Staphylococcus aureus (MSSA) Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes, Streptococcus pneumoniae including penicillin intermediate and macrolide resistant strains and was as active as ampicillin against Streptococcus agalactiae, penicillin resistant S. pneumoniae and viridans streptococci. Against Enterobacteriaceae amoxycillin-clavulanic acid in general, displayed weak activity with only Proteus mirabilis and Proteus vulgaris displaying levels of susceptibility above the 90th percentile. Amoxycillin-clavulanic acid had significant activity against many species of Gram-negative non-Enterobacteriaceae including Haemophilus influenzae, Haemophilus parainfluenzae and Moraxella catarrhalis but negligible activity against Burkholderia cepacia, Pseudomonas aeruginosa and Stenotrophomonas maltophilia. Amoxycillin-clavulanic acid continues to retain excellent activity against the majority of targeted pathogens despite 20 years of clinical use.

Comparative in vitro surveillance of amoxicillin-clavulanic acid and four oral comparators against 21232 clinical isolates from europe.

The present study was conducted to determine the in vitro activity of amoxicillin-clavulanic acid compared to that of four newer antimicrobial agents (ampicillin, azithromycin, cefuroxime and trimethoprim-sulfamethoxazole). All of the agents were tested against 21232 recent clinical isolates encompassing 37 species submitted from 16 European countries between 1997 and 1999. After 20 years of clinical use, amoxicillin-clavulanic acid continues to retain much of its initial activity against targeted gram-positive organisms, selected gram-negative organisms and major respiratory pathogens.

The formation of mixed culture biofilms of oral species along a gradient of shear stress.

A chemostat mixed culture system was used to produce two distinct ecological states, state-1 (caries-like microcosm) and state-2 (periodontal-like microcosm). Eleven bacterial species (Streptococcus gordonii, Strep. mitis I, Strep. mutans, Strep. oralis, Actinomyces naeslundii, Lactobacillus casei, Neisseria subflava, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella nigrescens, Veillonella dispar) were used to inoculate the planktonic system. A flow cell, designed to produce convergent flow with increasing shear stress, was attached to the chemostat system, and the resultant biofilms developed from the state-1 and state-2 microcosms along the shear stress gradient were examined and compared using image analysis and viable counts. The biofilm produced from state-1 showed a lower shear stress tolerance (0.146 Pa) than the state-2 biofilm (0.236 Pa). The biofilm compositions did not vary along the gradient of shear stress and were dependent on the initial inoculum conditions. Gram-positive species were predominant in the state-1 biofilm, while Gram-negative species were predominant in state-2.

Ecological effects of triclosan and triclosan monophosphate on defined mixed cultures of oral species grown in continuous culture.

The effects of triclosan and its phosphorylated derivative, triclosan monophosphate were studied using a continuous culture microcosm model. Two conditions were simulated, a caries-like state (pH 5.5 with artificial saliva plus glucose as growth medium) and a periodontal disease-like state (pH 7.5 with BHI plus yeast extract, haemin and cysteine as growth medium). Both cultures were maintained anaerobically at 37 degrees C at a growth rate of 0.1/h. Steady-state chemostats were pulsed with triclosan or triclosan monophosphate (initial concentrations between 20 and 40 mg/L) and changes in the ecological composition noted after 6 h. The caries-like microcosm steady state was dominated by streptococci, Lactobacillus and Veillonella sp. with low but detectable levels of Neisseria, Actinomyces and Fusobacterium sp. No significant ecological shifts occurred following pulses of either antimicrobial agent; all species were affected to approximately the same degree. The periodontal disease-like microcosm steady state was dominated by streptococci, Fusobacterium, Veillonella, Actinomyces, Prevotella and Porphyromonas sp. with low numbers of Neisseria and Lactobacillus sp. Significant ecological shifts were apparent following pulses of triclosan. The streptococci became the dominant group followed by Fusobacterium sp. For triclosan monophosphate, the streptococci again became dominant although Lactobacillus and Actinomyces were now the main sub-dominant species and Gram-negative anaerobes including Fusobacterium sp. were markedly inhibited. It is concluded that in the periodontal disease state, both triclosan and triclosan monophosphate affected the Gram-negative anaerobes to a greater extent than the Gram-positive groups and that this effect was more marked for triclosan monophosphate.

Nucleotide sequence of canine c-N-ras: codons 1 to 71.

The c-N-ras gene has been implicated often in the genesis and/or progression of human leukemias. To our knowledge, the sequence of this gene in the dog has not been reported. Using a system of asymmetric reamplification of double-stranded polymerase chain reaction (PCR) products, we have sequenced normal canine c-N-ras mRNA from position -26 to +213, including codons 12, 13, and 61, which are the sites where oncogenic mutations are most commonly observed. The canine c-N-ras sequence has close homology with the human sequence in this area; there were only 6 observed base differences in nucleotide sequence and none resulted in a change of the encoded amino acid. The results of this study set the stage for directed searches for c-N-ras mutations in experimentally induced and naturally acquired neoplasms of the dog.

Canine and bovine ras family expression detected and discriminated by use of polymerase chain reaction.

Cellular proto-oncogenes are highly conserved genes thought to be critical in cell growth and differentiation. In this study, we used human sequence designed oligonucleotide primers to detect and discriminate c-Ha-ras-1, c-Ki-ras-2 and c-N-ras genes of dogs and cows by polymerase chain reaction (PCR) amplification of genomic DNA (DNA/PCR). Further, we have applied PCR for analysis of expressed mRNA transcribed from the RAS genes (RNA/PCR).